
Launch HN: Prometheus (YC W19) – Remove CO2 from Air and Turn It into Gasoline - rmcginnis
Hi HN! I’m Rob, Founder of Prometheus. We’re removing CO2 from the air and turning it gasoline, diesel, and jet fuel. Since we use zero-carbon electricity from sources like solar and wind to make our fuel, there are no net CO2 emissions when you use it.<p>An article about us came up on HN recently and people seemed interested (<a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=19792412" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=19792412</a>), so we thought it would be good to try to answer some of the questions we saw there and try to dive in some more to any questions that follow!<p>The only inputs to make the fuel are CO2 and water (both from the air) and electricity. The only outputs are fuel and oxygen. One way to think about it is that making fuel is reverse combustion. The process isn’t super efficient (we expect 50-60% overall efficiency at maturity), but it turns out that doesn’t matter as long as the electricity is zero carbon and low cost. If the cost of our equipment is also low,  then we believe we can not only make zero carbon fuel, but actually compete on price with fossil fuel.<p>We’re not the first to make fuel from the air - in fact Google, Audi, Carbon Engineering, Global Thermostat, Climeworks, and labs at universities and national labs have all done it before us. What no one has been able to do so far is do it at a low enough cost to compete with fossil fuel.<p>The thing that’s new about what we’re doing is that we have gotten rid of all the thermal processes normally used, and instead use a process that uses only electricity (no natural gas, etc) and does it at room temperature. This is a big deal for both capital cost and for being truly carbon zero. We can use inexpensive materials, which keeps our cost low, and can start up and shut down quickly, which allows us to run intermittently, matching the intermittent nature of many renewable energy sources. We can also only run when the power is at the price we want.<p>Digging in to some more details, we absorb CO2 and water vapor from the air into an aqueous electrolyte. We then react the CO2 in the water with a copper catalyst to directly make alcohols like ethanol, butanol, propanol, etc. Both of these things have been done by many others and the science is known. Normally at this point one would have to use a thermal process (distillation) to get the fuel out of the water, and this is expensive and makes the economics really hard to get right. We don’t have to do this step thermally though, because we have a carbon nanotube membrane that replaces it, extracting the alcohols from water in a single step at room temperature. This makes a huge difference in cost. The last step is that we up-convert the alcohols to gasoline, diesel, and jet fuel. This last step is also well known and we can actually buy this step from others.<p>The carbon nanotube membrane that makes this all work is the product of 6 years at my previous startup, Mattershift. I was developing it for desalination and water purification. About 3 years ago I realized it could do this job, but it wasn’t clear that a startup could raise money for such an ambitious effort, especially one linked to a political issue (unfortunately) like climate change. When I saw the YC request for startups in carbon removal, I knew that the timing was right, and I founded Prometheus to do it.<p>Please let me know if you have more questions or feedback. I’ll do my best to answer any questions, but please excuse if I’m not able to go too far into details like our piping and instrumentation design, or other really specific things we wouldn’t want to help competitors with.<p>Thanks!
======
brilee
A few questions from a chemistry major

1\. why extract from the air when you can just put a device on the smokestack
of an existing coal or natural gas plant? The higher CO2 density of the
effluent will make things more efficient. 2\. Your key innovation isn't the
part where you pull CO2 out of the air; it's the nanotube-based reverse
osmosis process for separating ethanol from water. This process could just as
easily be applied to other fields. For example, bioethanol production
similarly requires a very expensive distillation step to extract pure ethanol
from the fermentation medium. Making that step more efficient would be much
simpler than reinventing the entire supply chain around carbon dioxide
extraction and subsequent reduction to ethanol.

~~~
neilwilson
"why extract from the air when you can just put a device on the smokestack of
an existing coal or natural gas plant? "

The process uses clean electricity to reverse the CO2. I suspect here we have
a timing issue. When the sun shines, the gas plant will be idle, and that's
when the spare electricity is available is used to reverse the process.

And the physical position - the gas plant is likely to be where the sun shines
less.

As ever we have a storage buffer problem.

~~~
worldsayshi
The co2 could be stored underground? I guess that could deal with the timing
issue at least?

~~~
KaiserPro
You'd have to separate pump and store it, when electricity is expensive.

I suspect the advantage of this system is that is doesn't need pure co2 to
work

~~~
Already__Taken
And if you were storing CO2 I suspect the first question is how do we liquify
it. So the advantage fades away.

edit: You'd probably want to store the electricity on-site instead for this.
At least if there's no CO2 to consume you can be in the electricity storage
business.

------
ossie
The unit economics around this are by no means perfect but the BIG point here
that should probably be in all caps is that fact that the thermal process is
displaced by the use of electricity. We could argue on what is used to
generate said electricity, but that is beside the point since this innovation
opens up many more possibilities than are stated here. We could also argue
about the comparative cost of produced energy vs conventional fossil, but lets
not forget that those same arguments were used during the early
commercialization of solar energy.

In my opinion, the conversion process should stop at the creation of alcohols
which can then be used as additives in E-85 gasoline for example, or in other
chemical applications that have a less direct and immediate carbon impact on
the environment.

I also think this innovation has a larger impact if it were used to bring
existing generators of emissions closer to being carbon neutral. It also
reduces the burden of being cost efficient on Day 1 since the carbon intensity
of large emission generators is already a cost they'd be glad to mitigate or
get rid of (esp if the process generates a valuable by-product). Imagine power
plant stack exhausts channeled through this technology, or if were
miniaturized and made a standard part of every fossil fuel combustion
engine...we could all be buying gasoline and selling ethanol before you can
say Prometheus.

~~~
ascar
> _I also think this innovation has a larger impact if it were used to bring
> existing generators of emissions closer to being carbon neutral. It also
> reduces the burden of being cost efficient on Day 1 since the carbon
> intensity of large emission generators is already a cost they 'd be glad to
> mitigate or get rid of_

I can't follow this argument. What exactly are you proposing? His process
still has a ~50% efficiency-loss, so even using all energy generated from
fossil generators would only mitigate a maximum of 50% emissions (even
ignoring all other efficiency losses here). And that obviously would be
stupid. That energy is generated for a purpose.

The whole point of his process is to use solar/renewable/carbonfree energy to
reverse carbon emissions. It would always be more efficient to just use less
electricity/energy in other situations.

~~~
ossie
In its base form this technology is mining a resource - carbon. Would you
rather mine in areas of low or high atmospheric intensity? Would you rather
capture it where you fund the whole operation yourself, or where someone else
(existing polluters) is willing to pay you to take it out of the air because
there is a regulatory cost to them putting said carbon in the air?

Maybe i should have been clearer. I wasn't suggesting using the energy from a
fossil plant to power this, but co-locating it to areas where there might be
more environmental and cost incentives to do so.

As i said in my earlier post, arguments on cost/efficiency are beside the
point. The huge deal here is the use of electricity (of any form including all
the advances to come in the future...solar cells in space, nuclear fusion
etc), to remove CO2 from the atmosphere. One can now envision a future
(regardless of cost or efficiency today) where we can sustainably keep the
earth whole.

~~~
shawabawa3
I imagine the only places you can realistic install this technology is next to
hydro dams/large wind farms where you can get very cheap electricity at
certain times, and there are likely no hydrocarbon plants in these areas.

I'm not sure it's reasonable to install this in a coal plant and try to source
cheap solar from hundreds of miles away to power it (if that were possible,
why would the coal plant be active? It can't compete with the energy you're
using to scrub it)

------
apo
I'm skeptical, but fascinated by what you're doing.

It sounds like all of the steps of your process are known, except:

1\. CO2 fixation uses only electricity - no natural gas or other fossil fuels.
It works at room temperature.

2\. Distillation of the immediate products (alcohols) is not necessary. A
carbon nanotube membrane solves the problem at room temperature through
reverse osmosis.

Correct?

If so, then why target fuels rather than alcohol production directly? Burning
gasoline puts the CO2 right back into the atmosphere, which seems like a half
measure.

Why not focus on delivering CO2-negative organic feedstocks instead and
possibly tap into the carbon credits market?

Edit: another question. How much flexibility/control does your process give
over the _kinds_ of alcohols you produce? For example, can you select for long
chain alcohols over short? Saturated vs. unsaturated? Cyclic vs acyclic?
Aromatic? Mono- vs oligohydroxylated hydrocarbons. Primary, secondary,
tertiary? etc.

~~~
rmcginnis
We could use the alcohols as fuels directly (in flex fuel vehicles), but this
wouldn't address the much larger market for gasoline. It's a simple and
inexpensive upgrade, so makes sense to do it. We will definitely take
advantage of carbon credits, tax incentives, etc too!

~~~
rlucas
If the alcohol upgrade to gasoline makes sense technically and economically
for you, why is it not commonly done with (presumably much cheaper and extant
in great volume) industrial alcohol today?

~~~
gridlockd
He said "inexpensive", not "economical". The whole process isn't economical
_yet_. Perhaps conversion is _more economical_ with _their particlar_ sorts of
alcohol though.

~~~
rlucas
Understood, although eventually it has to become "economical" or it doesn't
fly.

My point was, you can view the alcohols as a feedstock for the gasoline
production, and given that, you might just stream in large quantities of
already-produced and cheap grain ethanol etc. from Indiana.

~~~
hndamien
It is more likely that polluting methods (net non-zero) will be forced to
become uneconomical.

------
rfrey
Hi Rob. I'm CTO of a company that generates electricity from waste heat at
industrial facilities. Pipeline compressor stations often generate 35MWth+ in
waste heat, which we can use at about 20% efficiency to generate electricity.

Many pipeline compressor stations are not anywhere close to distribution lines
so just merrily pump this heat up their stack. Especially with new pipelines
where companies are battling (legitimate) environmental concerns, there is no
reason they would not install your tech, powered by a heat recovery system, on
every single proposed compressor station on the line.

We have actually modeled it with negative operating costs (using technology
from one of your competitors) and think we could get the pipeline companies or
the government (we're in Canada) to pay for it even in the face of bad
economics. If your system is a step change in effectiveness from those
systems, it could be a game-changer in this market.

Let me know if you'd like to explore this a bit. My email is in my profile.

~~~
dragontamer
> Pipeline compressor stations often generate 35MWth+ in waste heat, which we
> can use at about 20% efficiency to generate electricity.

Can the waste heat be used for distillation instead? To heat up the fuel/water
mix to separate the two cleanly?

It would seem to me that the future of "waste heat" is to actually utilize the
heat, instead of powering a relatively inefficient heat-engine. Perhaps
instead of 20% efficiency, you get closer to 100% efficiency since all you'd
be doing is running the fuel-water mix to the heat-source to evaporate the
fuel out (I presume anyway, I'm no chemist)

~~~
alexeldeib
re: waste heat, I've been thinking forever that someone must capture this.
I've generally assumed the economics don't work out or no one has cracked it
outside of scenarios like regenerative braking. We waste so much energy that
we could capture and put back to use.

~~~
sanj
Regen braking doesn’t use waste heat. It converts mechanical energy back to
electrical.

~~~
js2
And in so doing, reduces waste heat due to friction, which is likely what the
parent commenter meant.

~~~
agumonkey
Some say it doubles the lifespan of brake pads.

------
teej
I don't have anything new to add, other than to say - this is a very well
written startup pitch. I'm in awe of how clearly you've laid out the
opportunity.

~~~
hoorayimhelping
The only thing I have to add here is that a random stranger from the internet
is rooting for you. This post sounds awesome and has all the makings of a
classic American success story. Good luck!

~~~
oldjokes
It's almost surreal reading through the comments in this thread. I'm so used
to the internet being a constant wave of negativity and hatred of everyone,
especially in recent years.

This thread is such a nice break from that, feels so refreshing. I don't know
anything about this process but I hope it works out.

------
thereisnospork
If you really think the underlying economic problem with electrochemical CO2
to alcohols as fuel is the separation at the end you are in for a world of
(economic) hurt. Not that improving the aforementioned separation isn't useful
or valuable, its just not the lynch pin.

Take a really hard look at your economics, in particular throughput and
capital amortization (which scales proportionally to uptime!). Good comparison
industries are chlor-alkali, fuel cell, and water-electrolyzer. Aqueous Cu
catalyzed CO2 reduction - even if you are best in class for FY and efficiency
and durability - have atrocious current densities, diffusion limited, by the
standards of anything considered commercializeable.

~~~
rmcginnis
The separation itself is not the only thing that makes the economics
favorable. It's important that changing the separation makes the process
electricity only overall, and this is a big deal. We can run intermittently,
allowing low renewable power costs, and since there is no pressure or heat in
the system, we can use inexpensive components. When the capex is low, it
allows for a lot of other things to not be ideal starting out. Current
densities aren't going to be as high as water splitting electrolyzers or
aluminum production, for example, but that's ok in this context.

~~~
thereisnospork
Electricity costs more than heat, as a rule. (electricity = heat at pretty
much 100% efficiency)

Intermittent operation blows up CAPEX costs.

There's no heat in the system until you start dumping electricity into the
resistive heating of your cells - you won't ever be able to run at scale at
room temperature. A gallon of gas per second unit - something nicely sized for
intermittent operation at a gas station - would need to vent approximately 120
megawatts of heat.

Current densities are 1-2 OOM lower than water electrolyzer.

Cell CAPEX isn't nearly as catalyst dependent as the daily 'We've invented a
replacement for platinum in fuel cells' papers would make you believe. Nafion,
balance of hardware, and assembly man-hours are $$$.

I've been where you are (more or less): beware the superficially justifiable
assumptions.

~~~
rmcginnis
It's true that running part of the time is not as good as running
continuously, but if the capital is low enough, it's ok to start out running
intermittently until we get to the point where we have low cost dedicated
power and can have a higher uptime.

We will have to shed heat from the system to the environment, but that can be
done passively.

Current densities are likely going to be substantially lower, but our capital
costs are also going to be much lower. We don't need to operate at 30 bar for
example, nor further compress our product.

Our capital costs aren't magic, they're just good enough in balance with
everything else.

~~~
acidburnNSA
Hook to nuclear and hydro electricity and you can get your uptime much higher
while remaining carbon free. That should give you a good 2x boost on capex at
least.

~~~
pfdietz
Building nuclear plants to save on electrolyzer capital cost is not a good
idea at all. Penny wise, pound foolish.

~~~
acidburnNSA
Hook to existing plants to help them load follow where intermittent renewables
are at high capacity.

------
Damorian
How could the math possibly work out on this? If a gallon of gas holds 33.70
kWh of energy, and you can get cheap electricity for $0.1/kWh, you're looking
at $3.37/gallon if you have a magical process that converts with 100%
efficiency. Even if you hit your efficiency goal, which would be impressive,
who is paying $7/gallon for gas? Just buy an electric car. This can only
possibly be useful when all of the oil is gone and there is no other
alternative, right?

~~~
rmcginnis
We expect a gallon of gasoline to require approx. 60 kWh of electrical energy.
If the price of that electricity is below 5 cents, the economics work. If the
price is lower, the efficiency of the conversion could also be lower if that
optimized other costs (like capital). Electricity is routinely below 5 cents
now at utility scale (wholesale), which is where we will want to be.

~~~
danielmg
60 kWh capacity EV will get you (realisticaly) 200 miles.

A gallon of petrol - 40 miles (realistcally and using UK gallon).

According to Tesla their charging is 92% efficient so reduce that 200 to 184
miles.

Your process is 4.5 times less efficient than just putting that electricity
into the EV? Is that right?

If so - and your process is carbon neutral (big if) - what's the point in a
future where EVs dominate?

~~~
rmcginnis
In the long term, electric vehicles may indeed replace ICE cars. That would be
awesome. One way to see what we're doing is to make sure the path to that
future is good. We can't burn fossil fuels while we wait to replace the
existing vehicle fleet with electric cars. By using zero carbon we make sure
that we are solving the problem right away.

~~~
jnw2
You might want to focus on jet fuel, since we don't know how to make batteries
with sufficient energy density for long range flights and don't know if such
energy density will ever become possible.

It might also be worth looking at where airplanes tanker fuel, that is to say,
carry more fuel than they need for their current leg because refueling at the
next stop would be difficult or expensive. Apparently a lot of that currently
happens on short flights to small islands; while I hope Wright Electric and/or
the EViation Alice will eventually take over that market, in the short term
that's a market that might be willing to pay a bit more for liquid fuel made
from air plus local solar panels.

Fuel oil that can be burned in combined cycle power plants in the winter may
also be valuable for dealing with seasonal imbalances in demand vs renewable
generation that lithium ion batteries can't cost effectively balance.

------
garrettdc
This is really cool! I hope that you can rise above the comments of the "this
isn't good enough" or "zero carbon or bust" crowd. This type of innovation is
what we need to move the needle in a realistic manner and that helps to build
on the infrastructure that we already have in place.

I'm excited to see what comes of this in the coming years!

~~~
rorykoehler
I'm conflicted. This is clearly better than what we have but I was really
hoping for a carbon negative future. I hope projects like this are a stepping
stone and not a handbrake on progress.

~~~
ahje
If it breaks our dependency on fossil fuels then I'm all for it.

~~~
rorykoehler
Ye on reflection and reading more comments from the founder I'm tentatively
positive on this. Localised air pollution from burning of fuels and globally
elevated co2 levels are two distinct problems. Solving one is already a big
step in the right direction.

~~~
ahje
Precisely! Replacing all gasoline and diesel engines, if that's even possible,
will take decades. We need something other than fossil fuels for them in the
mean time.

------
mrguyorama
Would you be willing to share vague details of your roadmap?

Specifically; How many barrels of ready to burn gasoline are you outputting
per day in 6 months? 1 year? 3 years?

The fact that the general fuel is going to be sold and re-burned means this is
at best carbon neutral, so from a cynical environmentalist point of view,
what's the point? This can't help anyone unless you pump the synth-gas into
the ground and sequester it, but that isn't VC-backed viable.

If you are using some sort of membrane to pull out distillates without heat,
why wouldn't you just sell that to existing petro-chemical companies for their
distillation processes? What non-thermal-energy related benefits come with
this membrane?

The poster gave important information in another thread: 60kWh per gallon of
gas, aiming for ~5 cents per kWh, ~$3.00 per gallon into distribution
channels. That makes it instantly cheaper than petrol in, at minimum, the UK

~~~
tofof
_...the general fuel is going to be sold and re-burned means this is at best
carbon neutral, so from a cynical environmentalist point of view, what 's the
point? This can't help anyone unless you pump the synth-gas into the ground
and sequester it..._

The status quo today is that we are removing carbon from the ground and
putting it into the air. This replaces those fuels that currently come out of
the ground. It's still a big win, even if it's technically only carbon
neutral.

Even electric vehicles aren't carbon neutral, because they're mostly charged
by coal power.

Also: you suggest the synth-gas should be pumped into the ground. What would
be the point of converting the carbon dioxide to alcohol to gasoline and
spending electricity to do it? At a minimum you could just pump at the alcohol
stage.

~~~
solarkraft
An EV makes several times the motion from the same energy input.

> Even electric vehicles aren't carbon neutral, because they're mostly charged
> by coal power.Even electric vehicles aren't carbon neutral, because they're
> mostly charged by coal power.

Is thus an invalid/irrelevant argument.

I _can_ get excited about jet fuel however, since battery powered planes are
considerably less practical than their traditional counter parts with the
current technology.

~~~
Robotbeat
This is a completely accurate comment. Why is it downvoted?

I assume the company is operating in the US. In the US only _27%_ of
electricity is from coal and falling.
[https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...](https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_1_01)

And in California (where nearly half of the US's electric vehicles reside--
with EVs achieving a nearly 8% market share last year among light vehicles),
it's MUCH less than that. There's only a single, tiny 63MW coal co-generation
plant in the state, so coal power is less than 1% of California electricity.

> Even electric vehicles aren't carbon neutral, because they're mostly charged
> by coal power.

Additionally, it's absurd to compare two consumers of electricity, both of
which are flexible with respect to time of consumption, and just arbitrarily
say one is mostly coal power (which is false) and the other isn't.

We definitely need carbon neutral or even carbon negative industrial
processes. I kind of question the logic of going for fuels versus more
valuable non-fuel feedstocks, however. A _maybe_ 50% efficient conversion of
electricity to alcohols with a typical 20% energy conversion of fuels to
mechanical power gives you about an order of magnitude less efficiency than
battery-electric.

And if you ARE insistent on making carbon neutral fuels: Makes more sense to
focus on things that are super hard to electrify, like long-haul aircraft and
transoceanic shipping and maybe heating fuels for the far north (where air
source heat pumps lose their effectiveness in January).

But I'm glad an electrochemical process is being developed, here. Electrolysis
and related processes are much preferable, IMHO, than the more common thermal
processes.

~~~
jonnycomputer
If this process were to _only_ make transoceanic shipping carbon neutral it
would be well worth it.

~~~
erobbins
Except fuel oil used in shipping is like $1 per gallon or something similarly
low.

~~~
dodobirdlord
That said, for bulk low-quality fuel needs like shipping they could reduce
costs by skipping the upcycling stage and just burning the alcohol.

------
refurb
Interesting timing of Derek's Lowe's post on "In the pipeline".[1]

 _There are government levers (subsidies, tax breaks, carbon use taxes and so
on) that can change the economic landscape, but the paper estimates that you’d
need electrochemical efficiencies of at least 60% and electricity available at
4 cents /kilowatt-hr or better to make these ideas profitable (with the usual
30-year-amortization assumption about the plants themselves). How close are
we? Many of the processes are currently in the 40-50% efficiency range, and
need further scale-up work: within sight, but not there yet. And renewable
electricity costs vary a great deal by region. The best cases are getting down
around that figure, though, and continuing to improve._

[1][https://blogs.sciencemag.org/pipeline/archives/2019/05/06/sw...](https://blogs.sciencemag.org/pipeline/archives/2019/05/06/switching-
out-of-fossil-fuel-feedstocks)

~~~
rmcginnis
Yes, that data is from a recent Science review article:
[https://science.sciencemag.org/content/364/6438/eaav3506](https://science.sciencemag.org/content/364/6438/eaav3506)

I think the timing on this effort is right, from a cost of renewable power
perspective, as well from a growing consensus that it is very close to being
achieved. Hope to prove that soon!

------
DougWebb
How quickly could you pull CO2 out of the air if you were scaled up to make
full use of a typical nuclear reactor for the electricity? If you just stored
the output of that process rather than refining it into gasoline, diesel, or
jet fuel, how would that product compare in cost to drilled oil in the same
state?

My thinking here is that creating gasoline and selling it for immediate use is
at best carbon neutral, and at worst delaying the replacement of that
gasoline-burning equipment with an all-electric version. But if your focus was
on replenishing raw oil reserves for future (hopefully mostly non-burning)
use, you'll be removing CO2 from the atmosphere. To do it at significant scale
requires a lot of energy, and a nuclear reactor is much better at providing
that level of energy than other zero-carbon sources. The trade-off is nuclear
waste, but that's much more containable than the waste from non-zero-carbon
energy producers for equivalent amounts of energy. Eventually it could be
reprocessed to extract more energy from it as well, until the radioactivity is
used up.

------
0000011111
As a person with a background in Environmental Studies, a c o2 to fuel
conversion technology such as this sounds revolutionary! I am most curious
about the fundementals.

Can you give us more specifics on the process such as;

1\. What is the scale of the operation? Does this process need to be done at a
large scale to work out economically? 2\. Take a Boeing 737 for example which
has a fuel capacity of ~6,875 Gallons. How much would it cost to build a C02
refinery that could produce that much fuel daily?

3\. How much does it cost at a small scale? Say you have a miminal viable
product that can refine 100 gallons of gasoline per day. What is the cost of
that production in USD?

4.How many KWh of electricity would be required to refine 1 gallon of fuel
using your current prototype?

I would love to hear / see data your numbers.

Thanks, 01

~~~
rmcginnis
The smallest scale at which we can operate profitably is probably in the
100,000 gallon/year range, although that could go down over time. We will make
modular, mobile systems that don't have to be very big to be profitable. One
shipping container will likely be able to do 100,000 gal/yr for example.

The electricity required will be approx. 60 kWh/gallon.

~~~
__d
"60kWh/gallon" \-- is that gallon of gasoline? Or ethanol? Or CO2?

If you know the figures off-hand (to save me doing the chemistry), how much
water and CO2 is required to produce the gallon of output?

~~~
rmcginnis
Gasoline. Each metric ton of CO2 corresponds to approx. 113 gallons of
gasoline. The amount of water is approx. 1:1 by volume.

~~~
fooblitzky
Very rough calculation:

* 60 kWh / gallon of gasoline * 100,000 gallons / year * = 6 GWh / year * = 3.5 MW solar array (from on-line calculator) * ~ 18,000 m^2 of solar panels (500W, 1.9m * 1.3m) (roughly 3 football fields of solar panels).

~~~
tedmcory77
Not to be flippant; but doesn't that seem like a surprisingly small
installation for ~273 gallons a day?

------
ineedasername
Can you talk a bit about the waste-water left over? Assuming it's non-potable,
what does the disposal path look like? How much of such water is there at
scale, e.g., water-per gallon of petro-product? Thanks, sounds awsome.

~~~
rmcginnis
There is no waste. The only inputs are water, CO2, and electricity. The only
outputs are fuel and oxygen.

~~~
ineedasername
With respect, that answer skirts the question of what happens to the water.

You said you're using the nanotube membrane to separate petro products from
the water. What do you do with the water left over? What state is the water in
when the process is complete? Potable? In need of treatment by traditional
water treatment facilities?

~~~
icebraining
If water is an input and not an output, that implies it's consumed, not left
over.

~~~
eanzenberg
Yes, one of the things that gets glossed over many times in this field (I used
to do research in artificial photosynthesis) is that water gets consumed to
create the fuel, and is released as vapor from every engine's exhaust. So to
generate 10 million barrels requires about 10 millions barrels of pure water,
per day, to satiate the US.

~~~
rmcginnis
Yes, water is turned into fuel and oxygen. In most places the water can be
obtained from moisture in the air (there is much more water than CO2 in air,
and we are already mining the air, so we can get both). In the process the
fuel is separated from the water, which remains in the reactor, and is topped
off as it is used to make the fuel. No waste water.

~~~
pstuart
Somewhat tangential, but does your crystal ball show when we will start seeing
carbon nanotube desalination tech making it into the real world?

~~~
dzhiurgis
His startup was supposed to start shipping it last year...

------
jvanderbot
So, the goal is carbon-neutral gasoline.

Short term, I suppose your target is feel-good gas burning vehicles. Longer
term, do you envision this technology being used for clean(er) + carbon
neutral municipal power generation, or is the fuel type just wrong for that?

I ask because a stop-gap can easily become permanent, and it'd be unfortunate
to continue dumping particulates (pm2.5/10), smog, etc into the air in major
cities. One huge benefit of electric vehicles is you can make power where
population is scarce, and use it where the population is. You don't get that
with burner vehicles.

~~~
rmcginnis
In the near term, we will remove the damage caused by fossil fuel use. Our
fuel will burn much cleaner, so that's also helpful. In the medium to long
term, cars will switch to electric, but now we'll have enough time to do that.
As that happens, Prometheus will roll out new products made from CO2, like
carbon negative building materials, etc. It's important to look not only at
the end goal, but also the path!

~~~
amluto
Why will your fuel burn cleaner? Soot and NOx are fundamental to the
combustion process. I guess you have no sulfur, which is worth something.

~~~
all2
Gasoline and hydrocarbons in general are mixtures of many different kinds of
chemicals, and not 'pure' to some degree (the refinement process purifies to
some extent).

If this process produces a specific hydrocarbon or class of hydrocarbon, it is
feasible that common byproducts of combustion will not appear with their
fuels.

------
progval
My most immediate question (after others you already answered in this thread)
is about getting enough CO2.

When you start absorbing CO2 from the air, won't the CO2 in the neighborhood
be depleted very quickly? And I'm assuming you can't pump enormous amounts of
air either for various reasons (noise, energy usage, other environmental
issues). Of course there's wind to bring more CO2, but I'm curious about your
computations.

~~~
sjg007
Doesn't matter, air is a fluid, so diffusion works in your favor.

~~~
progval
Yes, but does it work fast enough?

~~~
sjg007
You can figure that out:
[https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2389....](https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2389.1982.tb01757.x)

------
twright
This is really cool, I have a two questions the last one maybe a bit sillier
than the first:

\- I'm not a chemist, maybe you said this implicitly, but roughly at what rate
would this capture a kilogram of carbon?

\- Why did you choose the name 'Prometheus' the titan who created man, gave us
fire, and as punishment for the latter part, had his liver eaten out by a
vulture every day for eternity?

~~~
rmcginnis
First question - each ton of CO2 captured is equivalent to approx. 113 gallons
of renewable gasoline. If we replace all fossil gasoline in the US, for
example, that's approx. 140 billion gallons, equivalent to approx. 1.2
Gigatons of CO2. You can more than double that for the world. If we include
all liquid fuels (including heating), it's larger still. It's a hugely
significant CO2 emissions reduction.

Second question - I chose Prometheus because the story is that he gave us
fire, and we have a responsibility to use it well. So far, not so good, but
now we can do better. I imagine him saying "here's fire, don't screw it up".

~~~
tofof
I believe you misread the first question. It wasn't asking for the numbers on
the conversion from CO2 to gasoline; it was asking about the rate at which you
remove CO2 from the air.

What's the expected total removal per year in, say, your first, fifth, or
tenth years of operation?

~~~
__d
Assuming that the generated gasoline is used, there's ultimately nothing
removed from the air.

It does reduce or eliminate the need to source gasoline from "fossil" sources
however.

------
noonespecial
If nothing else it would be a great technology for solar and wind plants to
employ on-site to convert excess power into fuel that could drive standby
turbine generators for the times there is no sun or wind.

Giant batteries are a pretty easy to beat cost and maintenance wise.

------
ineedasername
So if this is basically eliminating the traditional "distillation" phase by
using the membrane, do you envision a day when I can dip your membrane in my
beer and then poor off some moon shine?

~~~
rmcginnis
Yes, you could do that now!

~~~
ineedasername
Well then, I'd like to place an order for all of them.

On a serious note though, that does present a novel use for these membranes
within that industry. I imagine that optimizing the distillation phase for
lower energy use and/or the possibility of distinct flavor characteristics
that might coincide with alternate distillation techniques could be very
compelling. Freeze-distillation has its own unique characteristics, I'd be
surprised if this didn't also have some of its own.

------
__sy__
I've been super curious about alternatives to the Sabatier reaction. Nice
work!

Maybe I'd encourage you to think of yourself less as a fuel company and more
as a chemical precursor one. Outside of combustion, there are a ton of other
use cases in need of synthetic pathways.

~~~
rmcginnis
Thanks! We are also going to make carbon negative building materials to remove
CO2 that has already been emitted. Really anything now made from petroleum is
potentially replaceable with air mined CO2 and renewable electricity. Will
start with gasoline.

~~~
monk_e_boy
Automatic factory on Mars?

~~~
rmcginnis
You could make a lot of stuff from the CO2 in the Martian atmosphere, for
sure!

~~~
codethief
Not a chemist, but as far as I understand the process you're using to process
the CO2 also needs water or at least some other source of hydrogen? Where
would you get that from on Mars? (Sure, there _is_ water on Mars but not in
the atmosphere.)

~~~
__sy__
Most likely subsurface ice

------
MuffinFlavored
> we expect 50-60% overall efficiency at maturity

What efficiency are you at now and what happens to your startup if you never
reach that "maybe too optimistic" 50-60% goal?

~~~
rmcginnis
We will know what our starting efficiency is before next year, when we start
to produce and sell fuel. Anything above 25% works economically, and that has
already been demonstrated.

------
amluto
How small can you scale it? Net energy metering for small-scale solar is not
particularly widespread, and the terms are getting progressively less
favorable over time. If you can make an inexpensive unit to turn a few kW of
excess production for a few hours a day into fuel at 50% efficiency, you might
be able to sell it in some markets. Think of it as a 25% round-trip efficiency
battery with immense capacity that can supply winter heat or vehicle power.

edit: for some applications like this, alcohol might be a better end point
than gasoline.

~~~
rmcginnis
Our current prototype is the size of a refrigerator. One of the cool things
about our tech is that it can work well at small scale. We don't have to get
to a billion dollar plant to get the economics right. We could make a system
to fit in your garage and make fuel at home. This isn't our focus right now
because we want to solve the problem of CO2 emissions from fuel, so need to
scale as fast as possible. That's the commodity gasoline market.

~~~
NortySpock
Still, "refrigerator-that-produces-fuel" would probably be a hit with those
interested in living off the grid. Just an idea for a side market.

~~~
tedmcory77
Possibly, a licensing play? May be a way to inject capital to get to the
larger problem?

------
narrator
What's your Energy Returned on Energy Invested (EROEI) on that?

Specifically, this means if you took the gasoline you made from this and put
it into an efficient generator how much electricity would you get out of it vs
how much electricity you put into it to make it in the first place? This would
be very useful in comparing this technology to biodiesel as a method of carbon
sequestration for example. Biodiesel has other problems too such as using
arable land and depleting topsoil. This comparison would make a nice slide in
your deck.

~~~
aoner
I think you're making an incorrect comparison. This is basically an energy
storage system. What you could do is compare the EROI of the energy source
that provided it (say wind-energy) and factor in the process efficiency and
compare that with the extraction of a specific fossil fuel.

------
leemailll
CO2 only accounts for 0.04% of the atmosphere, guess you need to concentrate
or isolate it before pump into your solution, also gas solubility in water is
low, so you might need to reduce temperature or change air pressure to
increase CO2 solubility. I just read Haber-Bosch process today, looks like
your process could be similar.

You mentioned use nanotube to extract alcohol, is this process similar to
chromatography? Do your nanotube's half-life long and stable, and the
production now is in industrial scale and low-cost?

------
mgreg
Appreciate you're sharing some of these details (thank you). I have been
thinking about this same basic idea but with hydrogen and fuel cells but will
need to evaluate the merits of electricity -> gasoline vs. electricity ->
hydrogen.

Being able to work with existing infrastructure and vehicles and other
components designed to work with gas is a huge advantage. And of course the
simpler storage of gas vs. hydrogen is nice too.

In terms of efficiency we can do a little back of envelope calcualtions.
Prometheus converts electricity to gas at 60 kWh a gallon (33.7 kWh) or about
56% efficient. Hydrogen production via electrolysis comes in at between 44.5 -
55 kWh/kg-H2 (I've seen a wide range of estimates) for a kg of Hydrogen (33
kWh) so about 60-70% efficient.

Of course then there's the reverse process of burning gas or using a fuel cell
for electricity production. The Toyota Mirai gets about 68 miles per kg of
hydrogen and the roughly equivalent Toyota Camry hybrid gets about 52 mpg.

So boiling this down (if I got this right and my data is good):

Gas method: 60kWh -> 1 gallon of gas -> 52 miles = .86 miles / kWh Hydrogen
method: 55 kWh -> 1 kg of h2 -> 68 miles = 1.23 miles / kWh

Of course this ignores all the challenges to building the hydrogen
infrastructure, public fear (warranted or not) about hydrogen, capital costs
of both systems, etc. It's also likely the hydrogen conversion gets more
efficient than the 55kWh to product 1kg but wanted to keep this conservative.

~~~
aoner
I synthetic fuels are a temporary solution for cars. If you are changing car
infrastructure, IMO it makes most sense to switch over to electricity (highest
efficiency and you can use electrical car batteries to stabilize the grid).

Synthetic fuels will make most sense for aviation (higher energy density
compared to hydrogen), (possibly) shipping and as a transitional fuel for
transport to reduce our emissions.

Synthetic fuels could also be a solution for seasonal storage.

------
Timothycquinn
How sensitive is the systems to airborne sodium chloride if located near salty
bodies of water? I would assume that colocation with nuclear power would be
ideal and many nuclear plants are next to salty bodies of water.

Being an energy auditor in my early career in the energy sector, I'm very
interested in seeing such systems implemented to balance system loads during
off peak times which will make Nuclear (safe and well designed) more cost
effective.

~~~
mrpopo
I am a proponent of nuclear, but wouldn't use of extra energy during off peak
times apply to renewables even more so?

Unless there are massive improvements in efficiency and cost-effectiveness of
storage, adapting usage to production of intermittent sources seems like it
would maximize yield and minimize investment costs.

------
inflatableDodo
Are you using anything to do with those nano-spike catalysts? Was one of the
first things that came to mind when I read the pitch. -
[https://www.popularmechanics.com/science/green-
tech/intervie...](https://www.popularmechanics.com/science/green-
tech/interviews/a23472/co2-ethanol-interview/)

~~~
rmcginnis
Not using nanospikes, but there are many proven heterogeneous catalysts now
that can do the same job. Can't elaborate here, sorry!

~~~
inflatableDodo
Yayy, a mystery. I like mysteries. Could you elaborate on where you _could_
elaborate?

~~~
rmcginnis
The best catalyst for CO2 conversion is copper. There are papers that have
done an exhaustive analysis of alternative metals, and copper comes out on top
everytime. Adding it to other materials like carbon or other metals in a
heterogeneous material can help with Faradaic efficiencies. We are less
concerned with Faradaic efficiencies than overall efficiencies and costs,
which leads us to different optimizations than academic labs pursue - they
typically want very high specificity. We don't care as long as it burns in an
engine well :)

~~~
inflatableDodo
Think I got it, your aim is going to be whatever gives you the overall highest
specific energy of the outputs for a given combined cost of inputs, rather
than any chasing purity of chemical, as they can all be used. That's
presumably the rest of industry's problem and it is already setup for that.

edit - also, thank you very much for taking the time to reply to my blatant
attempt to work out exactly what you are up to, I really appreciate it. Is a
subject I find fascinating.

------
coryrc
In spring and early summer, electricity prices in the PNW go negative due to
hydropower minimum flows and wind power subsidies.[0] You said capex is low,
so setup a bunch and be prepared to get paid to make fuel!

[0]
[https://www.eia.gov/todayinenergy/detail.php?id=5110](https://www.eia.gov/todayinenergy/detail.php?id=5110)

~~~
rmcginnis
We will definitely take free power whenever possible!

------
skunkworker
How is this different from what the US Navy has been trying to accomplish with
turning seawater into Jet fuel? I know that they are extracting CO2 from the
water instead of the air, but I believe the last I heard they had large
inefficiency issues. And for them they plenty of power from their onboard
reactor.

~~~
rmcginnis
Google X did a project to remove CO2 from seawater and turn it into fuel. It
was called project Foghorn:
[https://x.company/projects/foghorn/](https://x.company/projects/foghorn/)

They couldn't get the economics right, but did succeed in making fuel. Their
tech lead is an advisor of ours and is excited to get there this time!

~~~
philwelch
What’s your perspective on naval applications in general? It seems like an
obvious first step. Resupplying carrier groups at sea requires a much more
expensive supply chain than the one that runs to your local gas station. The
Navy might even pay a small premium for the strategic advantage of not having
to rely upon vulnerable oilers to keep their planes flying.

------
frantzen
Hello Rob, thanks for the post! Has your company performed an energy return on
energy invested (EROI) accounting for your process? Few companies provide
comprehensive and transparent EROI and/or CO2 emissions accounting for their
product(s). I know you explained that the inputs are low-carbon; however (1)
“renewable” energy is still anywhere from 10-50 gram CO2 per kWh
(effectively), and (2) the CO2-intensity of your capital equipment can be
depreciated over the useful lifespan of said equipment and allocated to each
effective unit of energy generated (kWh or gallon?). I’m genuinely excited
about your technology; your low capital costs, inexpensive materials,
flexible/intermittent operations, and hopefully low maintenance cost — all
sound very promising.

------
eDISCO
Interesting proposition. 1\. Why would your process be more cost effective
and/or efficient than the commercially available processes for alcohol
production? Surely if the magic sauce is the nanotube alcohol/water separation
then conventional alcohol sources from fermentation will start using it at
some point and will be able to produce same fuel but cheaper and/or more
efficient. Maybe you can show that [photosynthesis -> organic matter ->
fermentation] is less efficient than your process using renewables as input?

2\. Why use CO2 from Air? At 400ppm, there is 500 times less CO2 in air than
in any powerplant exhaust, so using the same state of the art separation, for
the same throughput, your equipment should be ~500 larger? That seems like a
capex waste.

~~~
rmcginnis
The cost of the agricultural feedstocks to biofuels are not easy to reduce
further, whereas renewable electricity is getting less expensive and likely
has much further to go. I think CO2 to fuel will have a decisive cost
advantage over biofuels.

The reason to use direct air capture rather that going for higher
concentration point sources is one of scale. We want to produce fuel at scales
much larger than can be accommodated by any other means that capture from the
air.

~~~
bluGill
Why not go for the higher concentrations now? Why not target agricultural
ethanol plants now? I grant that long term they are limited, but why not use
them now?

Higher CO2 concentration seems like it ought to make your initial testing
easier.

Likewise, if you are really more cost effective than distillation all the
existing ethanol plants would love to replace their boilers with your system.
It seems like a simple way to get a small cash infusion selling to them. They
can convert their ethanol to gasoline as well, and have infrastructure in
place.

What I'm saying is don't bite off more than you can chew. If any piece works
now push it while getting the others working.

~~~
akavel
Maybe they need to quickly scale up because of VC backing and thus a
requirement for a high return on the investment?

------
dgudkov
I hope Prometheus becomes successful. As an interesting side effect - its
success may render the need for electric vehicles less acute and maybe even
not so critical at all. Especially given the not so environment friendly
battery manufacturing process.

In a sense, Prometheus is a competitor to Tesla.

------
solarkraft
> turns out that doesn’t matter as long as the electricity is zero carbon and
> low cost. If the cost of our equipment is also low, then we believe we can
> not only make zero carbon fuel, but actually compete on price with fossil
> fuel.

That's a lot of "if". How close are you to that?

If you plan to sell to car users, how do you plan to compete with electric
cars, that can get about 8x the use out of the electricity (and don't have
most of the many issues of combustion engines).

Am I missing something really obvious? Is transport through cable for direct
consumption prohibitively expensive from the energy sources you're planning to
use? Do fuel cells change the calculation? What's the advantage? Potentially
take over a rapidly dying market?

~~~
ncallaway
There are lots of current uses of fuel besides short-transit automobiles.

Large sea shipping, aircraft, and rockets will continue to use fuel for a long
time.

------
jppope
Congrats. Thats awesome.

Just guessing that real estate is going to be a consideration for this
venture. Where (geographically) do you plan on operating? Is there any
advantage to doing this in areas like Los Angeles/ Mexico City that naturally
trap automobile emissions?

~~~
rmcginnis
The best location is one that gives us access to the lowest electricity price.
The CO2 and water are in air almost everywhere (in a desert environment the
water is harder to get from the air, but CO2 is evenly distributed). We will
be next to utility scale wind, solar, and other renewable sources.

------
tgtweak
The Navy would be highly interested in this, as they've had a project in the
works for years (via NRL) to create jet fuel from seawater. They're basically
25% efficient right now, and the physical size of the device vs the output is
quite prohibitive... But the advantage of making jet fuel on the carrier
itself for the planes, by using onboard nuclear vs having to dispatch and
maintain a fueling fleet is quite attractive even at this efficiency.

Short summary here:
[https://youtu.be/ikt1oOnoKGg](https://youtu.be/ikt1oOnoKGg)

~~~
dredmorbius
A compilation of references going back over 50 years, at USNRL, MIT, and
Brookhaven NL.

[https://old.reddit.com/r/dredmorbius/comments/28nqoz/electri...](https://old.reddit.com/r/dredmorbius/comments/28nqoz/electrical_fuel_synthesis_from_seawater_older/)

------
Grustaf
So you are competing with batteries? I suppose batteries have much higher
roundtrip efficiency, but maybe there are other advantages to your technology,
like being able to rely on combustion engine cars?

~~~
rmcginnis
The main advantage of renewable gasoline over batteries is that we can
decarbonize the existing vehicle fleet without replacing it. Also, the very
high energy density of gasoline, diesel, and jet fuel will make sense for a
long time in Jet aircraft, long haul trucks, and ocean container ships, for
example.

~~~
cjbenedikt
The very high density is in hydrogen - actually.

~~~
photon-torpedo
And the best way to store hydrogen is to attach it to carbon atoms.

------
pdovy
You've elsewhere quoted 60 kWh per gallon of renewable gasoline. The US
consumed 391.40 million gallons per day on average in 2018 [1], and
concurrently had generation capacity for 1.153 billion kWh per day from non-
hydroelectric renewable sources [2]. That suggests that full replacement of
current gasoline usage would require ~23.48 billion kWh per day, which far
outpaces what is currently available.

Of course _any_ replacement of fossil fuels is a great goal, but just curious
where you see this going at scale, if it were wildly successful? It seems like
if you or others were able to scale this up massively, you'd run into unit
economics issues as demand for the required renewable electricity outpaced
supply, raising the price.

[1]
[https://www.eia.gov/tools/faqs/faq.php?id=23&t=10](https://www.eia.gov/tools/faqs/faq.php?id=23&t=10)
[2]
[https://www.eia.gov/outlooks/steo/report/electricity.php](https://www.eia.gov/outlooks/steo/report/electricity.php)

~~~
smlacy
The real question should be: How much improvement over time in the efficiency
of this process could be expected? 1.1x? 2x? 10x? 100x?

Every new technology goes through a refinement cycle where costs & resources
are reduced, and I would assume the same is possible here.

~~~
rmcginnis
We will likely make improvements primarily in capex, power costs, and
transportation to lower our cost of producing fuel. Fundamental thermodynamics
and overpotential limits will hold our efficiency to some cap, likely 75% or
lower. We could try to push higher than 60%, but there will be an optimum for
capex vs opex that will probably not favor the highest possible efficiencies.

------
phonebucket
What happens with the gasoline after it’s made? Does it get burnt again? I’m
guessing the energy released from burning that gasoline must necessarily be
less than the energy used in creating it. Then the net is going back to square
one with regards to CO2, but with a net loss of renewable energy?

I may well be off the mark here, so would appreciate it if someone could tell
me what I’m missing.

~~~
rmcginnis
The energy content of the gasoline is less than the energy used to make it
(only 50-60% efficiency), but the CO2 released is the same as the CO2 used. So
the energy efficiency is low, but the net CO2 emission is still zero.

~~~
Zenbit_UX
Is your device small enough that it could be placed to filter the exhaust
emissions from a fuel burning car and reinsert the newly created gasoline into
its fuel tank?

~~~
shawabawa3
powered by what? It would only make sense if there was a carbon free cheap
power source you could use to charge it - if you just take it from the car
battery you're wasting fuel as it's only ~50% efficient

------
politician
In order to have a pure output of oxygen and fuel from CO2 and water, don't
you need a pure source of CO2 and a very clean source of water?

Could you provide some more detail on how these inputs are obtained? How much
CO2 are you able to extract over a day? Do the input rates suffer from
depleting the accessible CO2 from the local airspace in the same way that
plants do?

------
s1artibartfast
Hi Rob, Great idea! I have ton of questions:

1) If you hope to target low cost renewable power, will you be operating
intermittently at peak production, or around the clock?

2) Does negative pricing of power factor in to your business model?

3) Do you think your process could economically compete in the market for grid
energy storage? I so, how does the costs and efficiency compare to other
methods?

~~~
rmcginnis
We are designing our systems to run intermittently, to match the intermittent
availability of renewable power. The capital cost of our systems is expected
to be low enough for us to run profitably even if we are only operating 50% of
the time. We expect we will get very low electricity prices because of this,
and even negative pricing some times. We are not positioning ourselves as grid
storage, but having our systems on the grid will balance demand for
renewables, allowing more to be deployed, which is a similar service. If we
can get paid for demand response, we won't turn it down!

------
toastypatty
Are you in direct competition with Carbon Engineering from BC, Canada?

~~~
rmcginnis
Yes indeed.

------
tfolbrecht
Get to keep current infrastructure, engines, powerplants etc? Check!

Get the probability of gasoline with carbon neutrality? Check!

What an exciting technology!

~~~
tfolbrecht
*portability Darn autocorrect

------
STRML
Incredible pitch, I wish you luck. This would be an amazing alternative to
batteries in areas where there would otherwise be renewable over-capacity.
While it appears less efficient, it is transportable and easy to store.

Please keep us all updated on how it goes, I'm sure you will see a lot of
excitement about what you are doing.

~~~
rmcginnis
Thanks, will do!

------
frantzen
Hello Rob, thanks for the post. I studied with Chichilnisky before founding,
and have reviewed Thermostat. Has your company performed an energy return on
energy invested (EROI) accounting for your process? Few companies (engaged in
fossil fuels, renewables, or CCS) provide a comprehensive EROI and/or CO2
emissions accounting for their products. I know you explained that the inputs
are low-carbon; however (1) “renewable” energy is still anywhere from 10-50
gram CO2 per kWh (effectively), and (2) the CO2 intensity of your capital
equipment can be depreciated over the useful lifespan of said equipment and
then allocated to each effective unit of energy (kWh? or Gallon?). I’m
genuinely excited about your technology; your low capital costs, cheap
materials, intermittent operations, and hopefully low maintenance cost all
sound very promising.

------
whatshisface
By law, gasoline gets cut with ethanol, degrading engine performance. If I buy
gas from you guys will it be legal to put 100% gasoline into my engine? If so
that's a "killer app," (so to speak) for people who care about their engines,
even if it is more expensive in early development stages.

~~~
lutorm
Why do you say ethanol degrades performance? Ethanol is an anti-knocking agent
when added to gasoline, so it actually enables higher performance.

~~~
averros
It degrades energy density of the fuel (by volume).

In other words, today's gasoline in US takes you 4% less distance than
gasoline from 70s.

It also creates problems with internal corrosion (which is why it is not used
in aircraft fuels), though modern auto engines are designed to deal with that
(and are more expensive because of that, too).

~~~
lutorm
Sure, the energy density is a bit lower, but that's not really what people
mean when they talk about "performance". "High-performance cars" don't usually
refer to cars that can go a long distance on a tank.

------
jandrese
Long term we need to do this and then pump the resulting alcohol back
underground or in some other reservoir where it can be more or less
permanently removed from the environment. Basically we've built up an enormous
energy debt from carbon that we need to repay to avoid cooking the Earth to
death.

------
baxtr
Great work! If this really works at scale distributed around the globe, fuming
lots of CO2 into the atmosphere maybe wasn't a bad idea after all. Since we
thus distributed it evenly around the globe, it can be harvested back
anywhere. Say goodbye to pipelines (in the far future).

------
the_watcher
I don't know nearly enough about the science to comment on that, so I'm just
going to assume you can do this. Would your ultimate model just be to sell to
gas stations? Create your own? Create a consumer product small and simple
enough for people to put it in their home?

This is really cool!

------
frantzen
Hello Rob, thanks for the post! Has your company performed an energy return on
energy invested (EROI) accounting for your process? Few companies if any
provide a comprehensive EROI and/or CO2 emissions accounting for their
product(s). I know you explained that the inputs are low-carbon; however (1)
“renewable” energy is still anywhere from 10-50 gram CO2 per kWh
(effectively), and (2) the CO2 intensity of your capital equipment can be
depreciated over the useful lifespan and then allocated to each effective unit
of energy (kWh or Gallon?). I’m genuinely excited about your technology; your
low capital costs, inexpensive materials, intermittent operations, and
hopefully low maintenance costs all sound very promising.

~~~
rmcginnis
Thanks! We haven't done a unique analysis yet, but here is a paper that does a
good overview of energy balances and efficiencies for CO2 to fuels and
products. In their separations discussion you can see why distillation of
alcohols is not favorable. A membrane approach is approx. 6x better, but until
the CNT membrane was shown to do this job, there was no practical way to do
the separation at this efficiency.

[https://www.cell.com/joule/fulltext/S2542-4351(18)30042-4](https://www.cell.com/joule/fulltext/S2542-4351\(18\)30042-4)

------
D_Alex
> we absorb CO2 and water vapor from the air into an aqueous electrolyte....to
> get the fuel out of the water...we have a carbon nanotube membrane

Considering the partial pressure of CO2 in the atmosphere is miniscule, the
eventual concentration of the product will also be very low. And because the
water molecule is the smallest, you will not be extracting fuel from the
solution, but rather extracting water until the fuel concentration is
sufficient. Together, this implies that the energy expended in separation
_must_ be high, and therefore the process _must_ be inefficient. Is this
correct, or have I made a bad assumption somewhere?

------
_Nat_
Why open-air capture?

I mean, it's typically much cheaper to capture CO2 from concentrated streams,
such as the flue gases from coal-fired power plants. So why accomplish the
same CO2 mitigation at higher cost by getting it from open-air capture?

~~~
rmcginnis
We want to get to >300 B gallons per year of gasoline, and only direct air
capture will scale to that level.

~~~
_Nat_
Even in the long term, it seems like you'd want to grab CO2 from point-
sources. Sure you might need to also grab CO2 from open-air if you reach such
a scale, but even at that point open-air would just be a supplement rather
than the sole source (unless there's a reason to favor open-air exclusively?).

So why start with open-air capture? Just seems weird to burn cash on a more
expensive way of accomplishing the same goal.

~~~
NortySpock
It takes time to integrate technology with existing utilities or businesses,
rather than just renting a building and opening a window.

I agree, they're going for the harder problem, but it's also the most scalable
solution.

~~~
_Nat_
> I agree, they're going for the harder problem, but it's also the most
> scalable solution.

It's not really harder, just more expensive.

When major point-sources give off CO2, it's more concentrated. Once it gets
into the atmosphere, the entropy goes up, and that entropy cost must be repaid
to capture it again. Technical challenges aside, it's still another cost to be
paid, making it more expensive.

I think people like the idea of open-air capture because it's just so easy to
imagine. I'd guess that it's also easier to pitch to non-technical investors,
largely because it sounds so elegant in its simplicity. I just don't see how
it makes much technical or business sense, beyond that sex appeal -- which, to
be fair, I can appreciate having its own uses.

Honestly, I'm skeptical that a robust analysis of the economics would yield a
favorable conclusion. But the market isn't entirely rational, and I can
imagine a strategy that sacrifices a measure of fiscal viability for sex
appeal potentially profiting for it -- I'm guessing most when pitching to
investors, but potentially when pitching to policy makers and the general
public?

Which I think is what I find so interesting here. I mean, this doesn't look
like a technically optimal strategy to me, but perhaps that isn't necessarily
a bad thing?

This is, say that they optimize the plan in a fiscal sense -- would it still
get funding from investors? Would people still want to buy into it as hard?
Would the HackerNews thread still have so many positive comments?

~~~
wazoox
Investors financed total nonsense such as solar roads. You don't need to be
efficient to get VC money, particularly nowadays with loads of free cash from
the central banks and low interest rates.

------
swebs
So what happens to the gasoline afterward? This seems only useful if you bury
it underground in an attempt to reverse climate change. If you just use it for
fuel, then is this anything other than a really inefficient electric car?

~~~
alanfranz
You could stop extracting oil from underground and just keep the existing
quantities of CO2 that currently exist. This would allow a "green" application
of all the existing engines (think ships) and many situations where going full
electric may be impractical.

------
beautifulfreak
I have high hopes for desalination with graphene or nanotubes, so I hope when
Prometheus is up and running, you look into it again. I'd love to know what
happens in your nanotube filters. I read somewhere that water can be ballistic
in certain nanotubes, with zero resistance, so I wonder if you stumbled upon
something amazing. You must be thinking about other uses. Too many comments
here belabor the obvious, which you must get all the time, so kudos for
sticking with it and overcoming resistance. It's cool that we don't ever have
to run out of gasoline.

------
blablabla123
Is it possible to take the stuff from the air and store it in wood? If it was
you could sell "CO2 storage furniture". This would make your business model
green green.

I cannot find the reference but I remember that a chemists organisation was
years ago suggesting one should buy furniture/wood products. (This certainly
sounds adventurous and I might not remember this correctly.) Certain types of
wood come from controlled wood growing/farming, and those trees grow quite
fast. So the bottom line was that they suggested to consider Wood a natural
CO2 sink.

~~~
TheTrueTDF
Good idea, we could even give it a name like "tree" and we could scale it up
to something like a "forest"

~~~
blablabla123
Thank you. :D I was thinking that one could additionally enrich the wood.
Being a porous material this shouldn't be too difficult, although probably one
should watch out that inflammability doesn't increase.

------
bit_logic
Are you going to open a few "carbon neutral" gas stations? It might be great
for publicity and marketing to open a few in dense urban areas with high gas
prices (like LA and SF). Look at what the Apple and Tesla stores did for those
companies. You could probably also charge gas prices higher than average by
attracting the environmental crowd who would be willing to pay extra to fill
their Priuses with carbon neutral gas. This would also work well as initially
your supply will be small and still scaling up the process.

~~~
andremedeiros
I would actually argue that they'd be better off competing on price, rather
than raising it (if at all possible and sustainable.) That way even the "but
it doesn't run on gas" nuts would have no excuse not to get this instead.

~~~
rmcginnis
Competing on price is the plan. It's a commodity, so the only way to replace
fossil fuel is to take market share by competing on price.

------
lostsock
This sounds amazing, thank you for sharing and for answering so many
questions.

I know that you focus is on scale, so you're not likely to pursue this, but
the prospect of a fridge sized fuel generator seems like a wonderful stop-gap
for the existing ICE cars.

Having one in your garage that produces fuel from rooftop solar panels when
there is excess generated, and then not having to worry about transporting the
fuel or going to a petrol station sounds like a wonderful future while we
transition to EV.

Really looking forward to hearing how this plays out, good luck.

------
radres
I still don't see any theoretical proof that your carbon nanotubes are going
to do this job more efficiently.

If they do, will they need any replacement? Are they reusable? How low the
reuse cost can be?

~~~
rmcginnis
There should be a peer review article with this data by the end of the summer.
Mattershift, the company that makes the membranes, got a DOE RAPID grant to
get bench and pilot data for this:
[https://www.aiche.org/rapid/news/08-27-2018/rapid-
manufactur...](https://www.aiche.org/rapid/news/08-27-2018/rapid-
manufacturing-institute-announces-2018-project-selections)

The membranes are robust and should have a long life in this application.

------
marauder016
I was excited to see the article and the response to this post is really
heartening. I will echo other comments by saying that your HN pitch is well-
written.

I do have a question: in conventional capture processes, the step that makes
the process cost-prohibitive is regenerating the absorbent or adsorbent
because it is so energy-intensive. You say above that CO2 (and water vapour)
is absorbed by an aqueous electrolyte. How do you separate the CO2 from the
electrolyte solution?

~~~
rmcginnis
The CO2 is absorbed in the electrolyte, and that's where we use it in the
catalysis process. It is turned into fuel within the electrolyte, then we
extract that fuel from it.

------
kresmoi
Does your 60kWh/gallon gasoline quote include the energy needed for airflow to
hit the production scale you expect? This is a significant cost and is why
[https://www.nature.com/articles/s41467-019-09685-x#ref-
CR33](https://www.nature.com/articles/s41467-019-09685-x#ref-CR33) proposes
integration with A/C systems.

------
RootKitBeerCat
How do we apply for jobs at this company. I’m sure people would like to
contribute to such a good cause! Put the internet to work for you!

------
andrewgstanton
Rob -- doing something (somewhat) similar using plastic as an input (instead
of co2) and getting oil as an output.

You mentioned you can compete with fossil fuels on (electricicity cost) that
would be very dependent on where you operate (where the energy is cheapest). I
suspect these would be the same places that bitcoin miners operate out from
(and for the same reasons). Is this true ?

Thanks!

~~~
rmcginnis
Yes, we could probably just generate a map of where aluminum smelters and
bitcoin miners operate to give us our short list of early sites.

------
Jackim
I read in the Bloomberg article that the machine itself hasn't yet created
"enough gasoline to power his Golf even a single mile". I assume you've
already made enough to power an engine in the separate steps? How long before
you think you'd be able to make a video taking gas from the machine and
pouring it into a tank?

~~~
rmcginnis
We are doing the system shakedown now, and have started making fuel. We'd like
to do a demo in the next few months, as long as it doesn't divert us from our
timeline. Everything we're doing has been demonstrated separately, including
the CNT membrane alcohol extraction, so there isn't really a technical risk
here. Everything we need to do now is focused on proving the economics.

~~~
Jackim
Very cool! Thanks for the response, and I wish you all the best.

------
ajmurmann
This is awesome and I couldn't root for you folks more. This is such a great
step towards saving the planet!

"What no one has been able to do so far is do it at a low enough cost to
compete with fossil fuel." I wish we as a society could properly account for
negative externalities in the price of fossil fuel.

------
fock
So, what's your current fuel output per squaremeter of membrane?

EDIT: read the Bloomberg-report and this reminds me a little bit of the cold-
fusion buzz and the occasional kid doing yellow cake in his/her basement. But
hey, today there's enough money floating around and why not bet a little ...

------
blake1
This isn’t going to let us electrify the transportation decrypt. Here’s some
back of the envelope numbers. An ICE is about 33% efficient at converting
chemical energy to kinetic. I don’t know how efficient this process is, but to
be generous, I’ll guess 75%. (I could be way off!) Factor in transmission
losses of about 2% to the refinery and 5% losses to distribute the fuel, and
you get about 6% of the generated electricity making its way to kinetic
forward motion. Contrast this with an EV, which has a battery roundtrip
efficiency of 99% and motors of around 85-90%. The end result is about 80% of
the generated electricity getting used.

Now, I hope we can electrify the transportation sector, but our current
generation and transmissions systems are inadequate. I am did he calculations
for the state of California, and found that they would need to be roughly
doubled in size. An immense undertaking, but a doable one.

However, I do not see us increasing the electricity generation and
transmission systems by a factor of 25, which would be required for this
technology.

------
bluGill
How much control over molecules do you have? Gasoline is a mix of things
(which changes based on season). I know today you can buy synthetic diesel
(last I checked 3x the price of pump fuel, but it has enough more energy to
make the difference between a win/loss in a race).

~~~
rmcginnis
We have pretty good control, but it's not necessary to make pure substances
like only octane, etc. A mix of C4 to C12 hydrocarbons and alcohols that meets
the ASTM spec is all we need.

------
ignorantguy
Congratulations. I wish you the best.

~~~
rmcginnis
Thanks!

~~~
MuffinFlavored
How much of what you are doing is "behind closed doors / patented / patent
pending"? If there was a list of materials needed to do this on a consumer
level, I could see a lot of people wanting to play around with this as a
hobby.

~~~
rmcginnis
Patented, yes. You could do the fuel synthesis in water on a hobby level, and
use a thermal still to get something flammable, but you wouldn't be able to
use it in an engine. It's pretty fascinating to work on though.

~~~
MuffinFlavored
Do you guys not have a landing page / website yet?

~~~
uranium
[https://www.prometheusfuels.com/](https://www.prometheusfuels.com/)

------
lutorm
This is a cool project! One question though: why is getting rid of thermal
processes an improvement? If you're getting electricity from solar, you can
get even more thermal energy from solar since the conversion efficiency for
capturing heat is much higher.

~~~
rmcginnis
The cost of solar and wind electricity is low and getting lower. SImilar
investments have not been made in renewable heat (like geothermal or solar
heat), so they are not as inexpensive. Also, a thermal process needs to run
continuously (24/7 if possible), whereas a pure electric process can run
intermittently, which is a better fit for the zero carbon energy resources.

~~~
lutorm
I'm thinking of something like
[http://www.absolicon.com/](http://www.absolicon.com/), concentrating
collectors for industrial process heat. Maybe the intermittency is a factor
though, you'd need a thermal storage to go along with it.

------
billions
Can you make vodka out of thin air?

~~~
rmcginnis
Yes, we have thought about having an "air bar" at events. Downside is we'd
have to make sure it was pure ethanol. Gasoline is easier, because it can be a
mix of many things that burn. Engines are much less picky than our livers.

~~~
incompatible
You could theoretically sell devices for people to install in their back yards
to brew their own fuel? Even assuming, for simplicity, the use of mains power
and ethanol fuel.

Edit: already mentioned in the "How small can you scale it?" thread elsewhere.

------
Invictus0
From what I can see, the catch here is that the process of producing the gas
is really slow.

------
pulse7
One can get alcohol out of water at room temperature (28 degrees Celsius) by
using pressure. Dr. Carl Jung used the distillation under pressure in 1908 to
get alcohol out of wine and get alcohol-free wine. Wouldn't the same process
work here?

~~~
rmcginnis
It's possible to do a deep vacuum distillation (and some people do this for
moonshine, etc) to get a useable fuel out. Farmers have made their own fuel
from time to time doing this. The economics aren't good enough to compete with
fossil gasoline though.

------
tbabb
How does your expected 50-60% energy efficiency compare to the current energy
efficiency of oil extraction? Extraction and especially refinement must be
pretty inefficient. How do the end to end costs compare, and why do they fall
the way they do?

~~~
rmcginnis
We expect to be able to compete with fossil fuels on price as we push the
price down to get more market share. The process of extracting oil and
refining it to gasoline is not inexpensive or easy. By comparison, making fuel
on site that doesn't need refining is potentially much less difficult and
costly.

------
ksec
At what sort of electricity cost do you expect to produce the fuel at same
price as current petrol?

( I am pretty sure even if it was 30% more expensive at Retail consumer will
still be willing to paid for Clean Petrol, and that 30% could be your profits.
)

~~~
fulafel
If climate change is going to be addressed, fossil fuel prices will need to go
up a lot.

------
ajnin
At what scale are you going to run the process ? Is it going to be large scale
refinery-like production facilities, or could it also be a small unit for
storing power in a remote location with plenty of sun but no power lines ?

------
skaminskiy
Even if it works you would do it only if it would make enough money. If market
changes for some reason and it is not profitable anymore than Planet is
screwed up again. There is no easy fix. Only just stop polluting CO2.

------
mrpopo
What would be the longevity and manufacturing costs of this carbon nanotube
membrane?

I assume it wouldn't impact the energy accounting itself by much, but I heard
nanotubes' main flaw is the inability to manufacture them at scale.

------
perfunctory
> If the cost of our equipment is also low, then we believe we can not only
> make zero carbon fuel, but actually compete on price with fossil fuel.

even if it can compete with fossil fuel, do you think it will also be
competitive with BEV?

~~~
ncallaway
Fuels are used in lots of places besides cars where batteries aren't
necessarily viable options.

Large transport ships, airplanes, and rockets all are a long way of from being
able to be electric.

------
skykooler
Is this something that could be turned into a consumer-scale machine? I
understand a lot of the high fuel cost on islands is simply from shipping the
fuel there - producing it on site with this tech would be a huge benefit.

~~~
rmcginnis
Yes, we could definitely do remote location fueling stations, like remote
airstrips, etc. Right now we're focused on replacing as much fossil fuel as
possible with zero carbon fuel, so that has us focused on the commodity
gasoline market. Later we may do small distributed systems as well.

------
SEJeff
It took me a bit to realize this was unrelated to
[https://prometheus.io](https://prometheus.io), which is a pretty popular
project which is posted about here on HN frequently.

------
chris5745
Very exciting! I believe these types of approaches will be greatly beneficial
in turning the tide of environmental change. However, I am curious about the
long (very long) term effects of this technology.

If atmospheric CO2 becomes a resource for the production of goods that do not
release the CO2 back into the environment for reuse, would there be a risk of
O2 overabundance? If left unchecked it could overcorrect for global warming
and usher in an ice age.

I imagine there’s a balance point for CO2 levels and finding and maintaining
that balance will be what determines humankind’s success in the long (very
long) term.

See, e.g., University of Maryland. "Rise Of Oxygen Caused Earth's Earliest Ice
Age." ScienceDaily. ScienceDaily, 7 May 2009.
<www.sciencedaily.com/releases/2009/05/090507094218.htm>.

~~~
malux85
>If left unchecked it could overcorrect for global warming and usher in an ice
age.

The entire point of being able to control it is that it's not just left
unchecked. We'll modify it while studying it, and then when it becomes so
routine it's trivial, we'll automate it.

~~~
chris5745
Re: “unchecked”: I was speaking more from an economic perspective, rather than
a technical one. If there is a new CO2 sourced product with a long lifetime
and the carbon does not return to the atmosphere for a long period, and it is
in high global demand, it could open the door to the issues I’m trying to
highlight in the original comment.

------
xtorol
Can you elaborate on "we use zero-carbon electricity"? How far abstracted from
electrical generation are you? What guarantees do you have that your
electricity is provided by low/zero-carbon sources?

~~~
rmcginnis
We're going to take the power at the renewable power plant, so we will be
certain that we are getting zero carbon electricity.

~~~
maelito
Solar panels or wind turbines do emit CO2 (e.g. construction, maintenance). Is
the amount of CO2 emitted per kWh negligible compared to what would be
captured from the air ? What's the ratio ?

------
hevisko
So, lets talk numbers:

Let's assume we have 100W (typically 12V) solar panels in ~1m Square space.
How many litres of alcohol/syntfuel will it generate during an (expected)
8hours of 100% power capacity in a day?

------
ummonk
>About 3 years ago I realized it could do this job, but it wasn’t clear that a
startup could raise money for such an ambitious effort, especially one linked
to a political issue (unfortunately) like climate change.

That is probably true, but unfortunate. FWIW I’m a major skeptic as to the
harms of climate change, but I still find your startup very exciting. Whether
or not climate change is an issue, having a renewable cost effective way to
convert energy into hydrocarbons would be amazing!

I’m curious whether you’re sticking to just focusing on the energy use case or
continuing to develop other use cases such as the earlier desalination. There
are likely lots of areas in industry where such membrane technology would
provide a useful tool in the arsenal of methods to separate chemicals.

~~~
rmcginnis
I'm focused on Prometheus and turning CO2 to fuel, but my previous company
Mattershift will make the membranes available for other uses.

------
GuB-42
That's basically what plants do. So the question becomes: what is the
advantage of your system over biofuels?

An obvious one is that you can use electricity from any source (I am thinking
nuclear), while plants are solar-only. But since you mentioned solar
electricity, I think a side by side comparison of a biofuel producing field
and its factory with a solar farm tied to your system could be interesting.

EDIT: In case it isn't clear, my point is not to call you stupid, I assume
everyone who wants to extract CO2 from the air also considered plants, and for
some reason, found that artificial means are somehow better. The real question
is why? For example I know that natural photosynthesis is not very efficient,
but there may be other reasons.

------
iamgopal
How do you measure efficiency ? Is it amount of energy spent to generate
equivalent energy worth of gasoline ? ( Will one megawatts solar plant
generate about 0.25 gallon gasoline per minute ? )

~~~
rmcginnis
There are a couple of kinds of efficiency, i.e. Faradaic efficiency vs overall
efficiency. We are talking about overall efficiency, which is electrical
energy turned into useful chemical energy.

------
hart_russell
I hope this becomes an immense success. Gives me hope for the future.

~~~
rmcginnis
Thanks!

------
lchengify
Are you having to choose specific production areas to get effective economics
for electricity? E.g., are you expecting to have to scale up a plant near
cheap electricity like hydro?

------
idorube
I understand you want to make money, but why not open source your work? I'd
imagine this would be the right thing to do. I'm sure you could still live a
prosperous life.

------
frankus
Leaving aside the questions of cost-effectiveness/carbon neutrality/etc of
e.g. corn ethanol, but can your tech potentially also make existing biofuels
more efficient?

~~~
rmcginnis
Yes, the CNT membranes will improve the efficiency of biofuels, but Prometheus
won't do that. My previous company Mattershift makes the membranes and will
sell them for other uses.

------
Ruedii
I had read something about using a nano-surface on the electrodes on this
process to improve the yield of desired products. Have you considered using
similar technology?

------
joelthelion
How much emissions do you expect from production and disposal of your
machines? How big an impact will that have over the entire life cycle of your
hardware?

------
pragmaticlurker
congrats.. what about the name clash with e.g. this?
[https://prometheus.io/](https://prometheus.io/)

------
pow_pp_-1_v
I am probably extremely naive but I have a feeling I am going to hear a lot
about this in the future and that I am witnessing the start of something
great.

All the best!

~~~
rmcginnis
Thanks!

------
UzhasKakoi
Thank you for the detailed description. I wonder what impact may this
technology have on nature. Plants after all need CO2 to exist.

Thank you. I’ll be rooting for you.

~~~
stephen_g
There is no risk in terms of taking too much CO2 out of the atmosphere. Over
the last couple of hundred years, humans have put several trillion extra
tonnes of the stuff in (by burning material sequestered over millions of
years). Further, this tech carbon neutral, not carbon negative. The advantage
is that when the fuel is used, it's just putting CO2 back into the air that
was there before, not adding more.

Hopefully this kind of thing, in addition to switching the electricity grid to
zero emissions tech will allow us to halt global warming where it's at.

------
plazmaphyujin
What are the companies that do the up conversion to final fuel?

Are there any other products remaining after the conversion from alcohols such
as propane, butane etc..?

~~~
rmcginnis
Some of the companies that do upgrading include Vertimass, Gevo, Swedish
Biofuels, for example, and there are some methods that are not under patent
protection that anyone can use. Basically a catalyst that dehydrates the
alcohols and oligomerizes them into longer carbon chains. No other products
than a combustible fuel.

------
yread
How long does the the carbon nanotube membrane last? How many gallons can it
produce before it needs replacing? And how much it costs to manufacture?

~~~
rmcginnis
We expect a long life for the CNT membrane, as it operates on clean internal
streams. They are actually not that expensive, so this is a small risk.

------
Ruedii
I had read a while back of the use of nano-texturing on the electrodes in this
process to improve the yield of desired compounds.

Have you considered doing this?

------
tomxor
What are the major challenges you have yet to face to make it economically
viable?

e.g manufacturing your nano material at scale or obtaining higher efficiency..

~~~
rmcginnis
There are no limiting factors to us scaling now.

~~~
geedy
So is it fair to say that basically your only constraint is the price of your
input electricity?

~~~
rmcginnis
That is the main input. We also have to keep the capital costs low, but that
looks good too.

------
Gravityloss
Cool, what do you plan to use for power source? (ie where is the electricity
cheap and carbon free?) Can the process be run intermittently?

------
miles_matthias
Love the pitch, keep us up to date. Any place we can sign up to follow along?
Google just gives Kubernetes metrics results :)

------
WheelsAtLarge
Can this process be used to make Ethanol at large scale from plant matter? And
can it be competitive with fossil fuels?

------
maelito
Correct me if I'm wrong, but planes look like a bad target for this fuel
substitute : for 1 kg of CO2 emitted, estimates give a ~2 (or worse, 2.7 - 4)
factor of radiative forcing (the potential for climate warming), due to the
water vapor released at high altitudes.

You'd have to capture 2 or 3 times more fuel that you'd burn in the sky for
this to be "net zero climate", which is a better metric than "net zero
carbon".

~~~
effie
You seem to be right about the forcing of water being much higher [1], but CO2
has a nasty property as opposed to water: it stays in the atmosphere for much
longer and contributes to warming for much longer than the water does. If
temperatures get really bad in future, we can limit burning fuels and all the
excess water will fall back down to oceans in few years. CO2 won't do such
thing as fast. So even if we can't decrease forcing due to aviation burning
fuel, it makes sense to make aviation use CO2 neutral fuels to keep the
concentration of CO2 low.

[1]
[https://pubs.acs.org/doi/full/10.1021/es9039693](https://pubs.acs.org/doi/full/10.1021/es9039693)

~~~
effie
Contrary to what I said above, it seems the effect of jet exhaust water is
more complicated and hard to evaluate... the problem is that unless there is
enough water for condensation, water molecule is lighter than oxygen or
nitrogen molecule, which means the high altitude vapor isn't likely to fall
down quickly.

------
msamman
Do you think a long term use case for this tech is as a storage method for
energy produced through renewables?

------
medunham97123
Rob,

I haven't seen anyone else ask this question, but I currently craft my own
biodiesel and was wondering if the maker / private owner market would be able
get access to buy fuel from this process?

I understand there might be tweaking of engine combustion profiles to make
that happen, but I think this is exciting and would love to support by buying
some of this amazing fuel without waiting for it at a gas pump...

------
andrewgstanton
Very cool, looking at another solution to attack the global plastic waste
problem with oil as an output.

------
kbutler
How is the scalability of of the extraction process, both in manufacture and
operation of the membrane?

~~~
rmcginnis
Both are highly scalable. The CNT membrane is available in commercial modules
now and can scale up further quickly.

------
tehjoker
For the reasons mentioned below I'm skeptical that this is a solution to the
climate problem. However, certain applications such as air travel do not
currently have safe viable non-carbon power sources. Even if this is more
expensive than fossil fuel, limited amounts of subsidized zero carbon fuel
(~1-2% of consumption iirc) can make air travel sustainable.

Best of luck.

------
jeromebaek
Looking for any software engineers?

~~~
cs02rm0
And if not, what do you need?

------
ddebernardy
Do you factor the carbon that went into producing the solar panels and wind
turbines?

------
cjrp
Out of interest, how does this differ from companies like LanzaTech?

~~~
rmcginnis
Lanzatech uses a biological process.

------
mrfusion
Could this be a superior method for generating methane on mars?

------
joshdance
Can normal people (like me :) support the effort of invest?

------
RueCambon
How is this different from what Opus 12 has developed?

------
woah
Could you also make a filter that distills liquor?

------
fopen64
God allows you to succeed. That would be awesome.

------
et2o
How do the carbon nanotubes do the distillation?

------
shrimpx
Can you hook a miniaturized-enough version of this device to your exhaust pipe
then and have a zero exhaust car that runs on water but is technically a
gasoline car?

------
pbreit
It did not occur to me that this is linked to politics until you mentioned it.
If you feel that is hindering oyu in any way, feel free to skip the mention.

------
daniel-cussen
What's YC like as a solo founder?

------
_pmf_
Sounds like the ubeam "works for very tiny numbers, everything else is a
scaling problem" con.

------
cagenut
hi rob, would you rather be jonas salk or john d. rockefeller?

------
ash4u8iit
i am interested in collaborating at india

9140451991 ashishtewari.ips@gmail.com

------
barking
The 50-60% efficiency does matter if wind power itself isn't all that green.

------
ash4u8iit
I am interested in the idea at india. please contact @9140451991

ashishtewari.ips@gmail.com

------
techslave
you are producing carbon emitting fuel. you process therefore needs to be
negative carbon, not neutral.

this will never succeed as a VC funded enterprise.

------
averros
Well, producing solar panels and such also requires energy input, and these do
have limited lifetime. What is the real full-cycle energy conversion ratio is?

Secondly... continuous distillation doesn't necessarily require lots of
energy, since a lot of it could be recycled with counterflow heat exchangers
and heat pumps instead of plain heaters (i.e. hot output and hot waste are
used to heat up input to close to the proper fraction boiling temp, and the
output and waste are only slightly warmer than the input mix). It still needs
energy input to deal with losses and entropy reduction from mix to separate
fractions, but this is also true about using any sort of membrane-based
separation.

~~~
lutorm
* producing solar panels and such also requires energy input, and these do have limited lifetime. What is the real full-cycle energy conversion ratio is?

I wonder what this is, too, but a typical 300W panel with 20 year lifespan
will generate something like 20MWh over its lifetime. You can't possibly use
anywhere near that much energy to manufacture it.

~~~
seppel
My personal pet theory is that the energy consumption is more or less
equivalent to the price. So as long as the solar panel is not economically
viable, it does not provide an energy surplus.

20MWh is not much, it's $500-$3000 worth of energy, depending on taxes and
stuff. Can you buy, install, connect, maintain, clean a 300W solar panel for
20 years for this price?

Edit: Also, 20MWh is quite high. That's 9h of perfect sun, each day, the whole
20 years.

~~~
beefman
Well-placed solar plants have capacity factors of about 20%, so 10MWh. That's
worth about $1200 at the retail end of the grid (or $2600 if your local
utility has gone bankrupt). At the production end, it costs anywhere from $100
for fully depreciated hydro[1] to $1400 for solar PPAs made by bankrupt
utilities[2] to $600 for new solar when you assume an unrealistic cap factor
and ignore Chinese subsidies[3] to $240 if you ignore a whole bunch of
additional stuff.[4]

1
[https://www.eia.gov/electricity/annual/html/epa_08_04.html](https://www.eia.gov/electricity/annual/html/epa_08_04.html)

2 [https://www.spglobal.com/marketintelligence/en/news-
insights...](https://www.spglobal.com/marketintelligence/en/news-
insights/trending/r3wsfcG5olaZwvNUizePeQ2)

3
[https://www.eia.gov/outlooks/archive/aeo18/pdf/electricity_g...](https://www.eia.gov/outlooks/archive/aeo18/pdf/electricity_generation.pdf)

4 [https://www.utilitydive.com/news/nv-energy-23-cent-solar-
con...](https://www.utilitydive.com/news/nv-energy-23-cent-solar-contract-
could-set-new-price-record/525610/)

~~~
hef19898
Last time I checked retail prices were around 0.30 to 0.32 $ per Wp for large
customers. So your high efficiency, last tech 300 Wp module would be around
100$ including shipping for large orders. Could go up to around 120 to 150 for
smaller volumes. Of course, market prices may vary depending on demand and
availability.

------
JudgeWapner
how many watts today is required to produce one liter of fuel using both your
membrane and the conventional way requiring distillation? What are your long-
term watts/liter targets ?

Maybe a non-membrane version could be attempted that used renewable energy
(sunlight) to do the boiling? Certain geographic regions might have the right
combination of plentiful sunlight, water, and wind to minimize all these
costs?

~~~
rmcginnis
It will take approx. 60 kWh/gallon of fuel, or just under 16 kWh/Liter. As
long as this electricity is from zero carbon sources and is inexpensive
enough, it works. Distillation and other thermal processes typically need to
burn fossil fuels. The difference between renewable electrical energy only vs
using thermal is really more a difference of kind than of degree. It's really
hard to do a thermal process that is truly zero carbon, and hard to do it
economically as well.

~~~
JudgeWapner
how much energy is spent pulling CO2 out of the air? I know this sounds like a
step backward, but perhaps burning plant matter or recycled cardboard might be
a more efficient source of CO2? If purifying smoke is cheaper (energy-wise),
maybe you could let mother nature extract the CO2 through fast-growing plants,
then dry and burn them?

------
skookumchuck
How does this compare with planting trees and harvesting the wood as fuel?

------
Toine
> please excuse if I’m not able to go too far into details like our piping and
> instrumentation design, or other really specific things we wouldn’t want to
> help competitors with.

"I'll save the planet and my children only if we get super rich"

Is this peak capitalism ?

------
holy_city
Is your supply chain carbon neutral?

~~~
rmcginnis
The inputs are zero carbon, but there will be life cycle (LCA) impacts in the
materials of construction. We'll likely be well in carbon negative territory
even including materials, and will do a LCA to verify this when we get a
chance.

------
lucb1e
It's never said explicitly and I couldn't find a question about it, but
everyone talks as if we'll need solar input to power this. I assume this means
the machine doesn't produce enough fuel to power itself?

At any rate, _amazing_ product. Can I (eventually) buy one of those machines
or donate somewhere to make my area CO2 free?

~~~
rconti
Are you asking if this is a perpetual motion machine?

Edit: Or close enough to perpetual motion that it only requires the occasional
replacement of nanotubes and other materials

~~~
lucb1e
Please see the sibling thread that asked the same question a few minutes
earlier (probably wasn't there when you loaded the page). I replied there:
[https://news.ycombinator.com/item?id=19844137](https://news.ycombinator.com/item?id=19844137)

------
jyriand
My two cents — change your name. Prometheus us too pretentious in my opinion.
Also, Prometheus can be pronounced in different ways. Is it pronounced
PromEEteus or PrometHeus? And its also ProMeth. :)

~~~
yeukhon
Most importantly, Prometheus is a well-known
software...[https://prometheus.io/](https://prometheus.io/)

------
deepsun
Prometheus is the most popular time-series metrics database and query engine
for monitoring. It's really great, highly recommend!

------
freebear
"Google, Audi, Carbon Engineering, Global Thermostat, Climeworks, and labs at
universities and national labs have all done it before us. What no one has
been able to do so far is do it at a low enough cost to compete with fossil
fuel." So Google failed but Prometheus will succeed.

Are you just trying to make a buck in The End Times?

I have no feedback, Mother Earth has, probably a couple of hundreds of them
loops... We are screwed.

------
aj7
To make combustible fuel from solar energy is crazy. The cost of such fuel is
almost zero from the large oil reserves: the price you see is carefully
calculated to maximize profits and to politically permit less efficient
suppliers to survive and profit acceptably: but any synfuel business can be
wiped out any time. At a point where we are trying for a renewable electric
ecosystem, to take its product, and turn it inefficiently back into fuel is
ununderstandable. By the way, if electricity is free, please send me some.

~~~
dragonwriter
> To make combustible fuel from solar energy is crazy. The cost of such fuel
> is almost zero from the large oil reserves

...if you ignore the costs that exist in the form of environmental
externalities, a behavior which is increasingly being recognized as an
existential threat to human civilization.

~~~
aj7
I see, in other words, you have a method of capturing the externality costs,
and using them to protect this fledgling enterprise. Look, I understand
externalities. I understand 415ppm. I live in Hollywood, FL, and see flooding
at high tides, with my own eyes. But the proposition here is to turn solar
electricity into combustible fuel. And waste at least half of this energy in
practice, because we have some "valuable" investment in fossil fuels
infrastructure. Again, are you kidding me?

------
danieltillett
This can’t work because of Jevon’s paradox [0]. Every barrel of gasoline
created by this process just displaces a barrel of fossil gasoline, pushing
down the price of gasoline at the margins resulting in increased consumption.

CO2 neutral gasoline can only work if you can get the cost below the marginal
cost of production of fossil gasoline such that the oil stays in the ground.
This is a massive ask on thermodynamic grounds.

0\.
[https://en.wikipedia.org/wiki/Jevons_paradox](https://en.wikipedia.org/wiki/Jevons_paradox)

~~~
mrob
Jevon's paradox only applies because governments subsidize fossil fuels by
failing to correct the market failure of their externalities. If they were
taxed appropriately to compensate for the damage they do then synthetic
hydrocarbon fuels would probably be viable in the cases where batteries are
unsuitable because of insufficient energy density (e.g. long-distance
aviation).

~~~
danieltillett
No. I think you really need to understand Jevon's paradox. I highly encourage
you to do so - once I learned about it so much of the world became clearer.

~~~
mrob
The price does not need to be below the marginal cost of production of fossil
fuel. It only needs to be below the cost of production + the cost of taxes on
fossil fuel. I suggest that a taxation level that allows Jevons paradox to
occur is too low.

~~~
danieltillett
Taxes on fossil fuels just raise the marginal cost of production. They are a
totally separate issue from the effect of introducing a new fuel into the
market.

Given the amount of down voting I have received basic economics is not popular
on HC. Increasing the supply of gasoline will reduce its price which will
cause increased demand greater than the original supply. The original example
used by Jevon was coal consumption which rose 10 fold as the price halved. If
Promethus succeeds they will cause an increase in consumption of fossil fuels
(assuming no other changed) as they will lower the price of gasoline
increasing its consumption.

The only way that such an approach can work is if they can get the price of
gasoline below the cost of production from fossil fuels. While this may be
possible, on thermodynamic grounds it is hard to compete with all the stored
sunlight in fossil fuels, let alone the sunk costs in the fossil fuel
infrastructure.

I am very much in favour of doing something about us burning fossil fuel, but
I want us to concentrate on those things that make economic sense. In respect
to gasoline that would be electrification of the transport system and better
electric storage.

The one thing that would potentially be worth pursuing is not the production
of gasoline, but avgas (diesel) as there really is no viable alternative to
these for air and sea transport.

~~~
mrob
>Increasing the supply of gasoline will reduce its price

This is not an inevitability. The state can and does tax things, and I am
suggesting that they should tax fossil fuels sufficiently to prevent Jevon's
paradox from happening. The correct taxation to prevent the market failure of
externalities is not any percentage of the production cost, it's the cost of
the harm done. If Jevon's paradox would increase the harm done then tax should
increase to prevent this.

~~~
danieltillett
There is no need to have some alternative gasoline in order to implement a tax
to decrease consumption of gasoline. Just a straight carbon tax would do this.
The problem of course has been getting these implemented.

We really should keep the topic of what Prometheus wants to do seperate from
other things like carbon taxes.

I think the best bang for our buck would be to just buy the oil before it is
pumped out of the ground and leave it there. The producers would stop fighting
us doing something about climate change and the increase in gasoline prices
would drive the adoption of carbon neutral energy sources.

------
34k5jo3i4toig
IMHO this is a waste of time. You are wasting clean energy sources to make
dirty ones -- at best a 50-60% loss of energy. And you end up with dirty fuel,
that further produces CO2, in which the cycle repeats, with a net loss.

In the near future, cars and trucks will be electric. This is shuffling
deckchairs on the titanic. Why not put 100% of your efforts into electric
vehicles powered by 100% renewable sources?

~~~
rmcginnis
If we want to stay below 2 degrees C in warming, we don't have time to replace
the existing vehicle fleet (approx. 1.2 billion cars, trucks, buses, etc) with
electric vehicles. If we instead replace the fuel, this can be fast enough.
Even if all vehicles are electric in the future, this is still the right thing
to do now.

~~~
34k5jo3i4toig
My issue is that this is a step in the wrong direction, it is incentivizing
the current dirty status quo. Why would anyone replace their dirty engine if
they can feel good about by using your 'cleaned' fuel.

I agree we need to do something now, but this is just putting off the
inevitable. Re-engineering dirty fuel sources doesn't buy us time to resolve
this. It is procrastinating, shuffling titanic deckchairs.

The main advantage of this tech I can see is making 'primary' sourced fuel
illegal, 'secondary' sourced fuel like this prohibitively expensive, and
forcing everyone to go pure electric engine by economy.

~~~
bluGill
The energy density of batteries is nowhere near as good as oil - the laws of
physics limit how good batteries can get (there is some room for improvement,
but oil is still better by a large margin).

------
scrape_it
Very promising but I'm going to hold out until I actually see this being
applied in places like South Korea, literally suffocating from a combination
of both local and foreign smog from Korea's favorite neighbor.

You can't really fault me because we've often seen groundbreaking,
extraordinary claims, and very little of it is actually realized. Sort of like
how we get news about how somebody found a cure for AIDs or Cancer. Again, not
trying to shit on anybody, just practicing good old skepticism, I will believe
it when my nephews and nieces in Korea are able to breathe in cleaner air and
can play outside without wearing industrial face masks. Until then, fingers
crossed and hope this is the real deal.

~~~
rmcginnis
I totally agree on skepticism. We are working hard to prove our economics. We
are targeting selling renewable gasoline from the air for a profit next year.
It will be much better for air quality too!

~~~
kaennar
How will this improve the global average of air quality? If you are removing
the CO2 from the air then reintroducing it back into the same environment
(assuming it is not repurposed in another sector e.g. jet fuel, commercial
containers) wont the net effect be the same?

I understand this will concentrate the pollution significantly and may even
reduce it in the short term, but wont the average effects be the same?

~~~
thinkcontext
By "air quality" I believe he is saying that an extra benefit to being carbon
neutral is that their fuel combusts more purely than fuel made from crude oil.
This means less SOx, NOx, particulates, etc.

------
s1512783
Here's what I don't understand - You're taking CO2 out of the atmosphere using
renewable energy sources. Thermodynamically, this will take at least as much
energy as it took to burn them. You did not mention how energy efficient your
energy storage method is right now (50-60% at maturity sounds _really_
optimistic, when plants are only a few %), but, in the short term, while we're
still mostly using carbon-based fuels, you're basically diverting renewable
energy capacity from consumers. Instead of getting 1kWh of usable energy from
a solar panel, they're getting _at best_ 0.5kWh, albeit in a much denser form
that's easier to move around for some transportation uses, such as aviation.
But, in the short term, you have a net-negative impact.

In the long term, if things keep going where they are going and we end up
having to remove carbon from the atmosphere to reverse some effects of global
warming, why would we want to convert it into gasoline instead of e.g. just
capturing it and storing?

Or is this just a way to generate jet fuel for planes of the future when we'll
electrify all of transportation except for flying?

~~~
rmcginnis
Demonstrated overall conversion efficiencies for CO2 to fuels are already in
the 25-50% range, depending on the fuel. We are confident we can get to at
least 50% for our process. We will not be taking renewable power away from
other uses - in the short term we'll be using marginally useful power (wind at
midnight, solar at noon, etc), as we need the power to be low cost, and any
time it has higher value uses, it won't be cheap enough. So we are not
removing it from other beneficial use. Also, as we scale, we will cause much
more solar and wind power to be available as we will be buying a lot of it. In
the long term, aviation and shipping are likely to still use liquid fuel, yes.

~~~
s1512783
Thanks for the reply, I get the load balancing part now, I did not think about
that.

I was thinking a lot recently about flying and how we could make it work in
the (hopefully) greener future. This is definitely a more sensible way of
doing it than electric jets, good luck with your company!

~~~
rmcginnis
Thanks!

