
Producing industrial hydrogen from biomass - grantlmiller
https://www.charmindustrial.com/blog/2019/3/17/making-grass-flow-like-water
======
warent
_" Obviously we just needed a steeper cone angle, so we fabricated one at 75°
but it still jammed. Perplexed, we increased the angle to 82.5°—practically a
straight pipe—and it still jammed. Thus began our surprise introduction to the
field of bulk material handling, where entire books have been written and
companies have been founded solely to solve this issue known as ‘bridging’,
and the frequently-associated ‘hammer rash’."_

This is hilarious I think partly because it's such a common theme in
engineering or life in general. For some reason things that initially seem so
benign and straight-forward end up becoming absolute rabbit-holes of startling
complexity.

------
torpfactory
Looks like they've got some bad Funnel Flow in the hopper. Mass flow is
probably the desired flow regime. Using a non-conical hopper is probably a
better idea and would negate the vibration, which can fail.

Typically only change the shape of the hopper in one direction at at time as
you move down. This often leads to hoppers with an exit that is a slot and not
round.

We've used these powder consultants before and I took a week long course on
hopper design: [http://powdernotes.com](http://powdernotes.com)

Edit - another method we use to create empty-able hoppers: fluidization. Not
sure if this fits with your processing strategy but it also mixes the powder
somewhat which prevents size segregation of the particles. And this video is
pretty cool:

[https://www.youtube.com/watch?v=My4RA5I0FKs](https://www.youtube.com/watch?v=My4RA5I0FKs)

~~~
utexaspunk
Could the grass be blown in? Leaf blowers move grass pretty easily...

~~~
whatshisface
I would imagine that leaf blowers operate at a much lower density of grass, in
an open area where there's nothing for a grass blade to stick on.

------
ada1981
My initial thought was vibration, so I was happy to see that was the solution!

I’ve been in bed sick all day with a terrible cold and my sinuses are packed
solid.

I had a headache and so out of bordeum tried using my black and decker buffer
to massage my head and relieve my headache (I use the buffer as an awesome
massager and modded it with a variable speed switch).

To my surprise it worked on the headache and also liquified my sinuses.

A quick google search turned up a few other people playing with vibrators for
congestion and at least one patent.

Funny to come across this after experimenting with getting solids to behave at
liquids via vibration all day.

~~~
dsfyu404ed
>I had a headache and so out of bordeum tried using my black and decker buffer
to massage my head and relieve my headache

I think the logical next step is to put a boxing glove on a sawzall.

~~~
utexaspunk
Oh god, you just reminded me of this:
[http://www.thebaynet.com/articles/0309/update-bloody-
tragedy...](http://www.thebaynet.com/articles/0309/update-bloody-tragedy-in-
lexington-park.html)

~~~
ada1981
DIY Fucking Machines gone wrong.

------
thinkcontext
I'm skeptical of most bioenergy projects that involve growing things in a
field. The best by far I've seen is seen is Brazilian sugarcane to ethanol.
Sugarcane is around 8% efficient at converting light into biomass, for
comparison corn which the US uses for ethanol is 1-2%. Of course you then have
to process those into something else to allow us humans to make use of that
energy, so real efficiency is lower.

Compare that to PV solar which is around 18% in a form that humans can use. Of
course electricity is more difficult to store than ethanol and hydrogen but
there's a big efficiency advantage that has to be made up.

Much better would be to use organic waste. People have to pay to get rid of
that stuff so if you can make it your fuel there's money to be made.
Hydrothermal gasification or liquification both seem promising for that.

~~~
chimere
(Co-founder at Charm) Fair points. I'm not going to defend corn ethanol - our
process yields 10x more saleable energy per acre than corn ethanol. The energy
crop we're currently field trialing is similar to sugarcane, with extremely
high yields (and our process uses the entire plant, unlike ethanol). Of
course, energy crops are only required at large scale. At small scale, there's
plenty of agricultural waste available for cheap, as you mentioned.

PV certainly wins on efficiency compared to crops, but it's also relatively
expensive (an acre of PV vs an acre of perennial crops). Also PV is quite
unremarkable at removing CO2 from the atmosphere :]

~~~
iso1337
Looks like Miscanthus grass. Although shouldn't it not matter? Why not partner
with a corn grower and use corn stalk or chopped corn cobs? Or gasify
cardboard.

------
throwaway5752
So many questions.

How much geological sequestration capacity exists, how long term is the
sequestration, and what is the cost of securing it at the necessary scales? Is
feedstock local to sequestration formations, and if not, has the transport
been factored in?

Why not biogas as a turbine feedstock and sell carbon neutral electricity on
the grid (offsetting extracted hydrocarbon)?

What about hydrogen being (my understanding) an indirect plastic byproduct?

What was the drawback of monetizing bio char volatiles while selling the
"waste" as a soil amendment products?

I only ask these because I very much want this to succeed and I'm glad to see
this here. I get the feeling that the point is very much finding an economic
basis for sequestration.

~~~
pkrein
One of the Charm co-founders here. Great questions, and you're correct the
point is to find an economically profitable basis for sequestration.

1\. In North America alone we have 32,000 gigatons of geological sequestration
storage capacity... about 900 years of global carbon dioxide emissions.
[https://en.wikipedia.org/wiki/Carbon_capture_and_storage](https://en.wikipedia.org/wiki/Carbon_capture_and_storage)

2\. We looked at generating electricity, and many others have built and
operated biomass-to-electricity plants. The economics don't work out...
electricity is very cheap. Most of the biomass-to-electricity plants in
California are closing up shop now.

3\. Hydrogen may be a byproduct of some plastics manufacturing processes, but
not nearly on the scale consumed.

4\. Yes, hydrogen _is_ a (cleaned up) biochar volatile! We consume most of the
biochar itself as the energy source for heating the gasifier. Any excess
biochar will be sold as soil amendment.

~~~
strainer
"In North America alone we have 32,000 gigatons of geological sequestration
storage capacity"

I suspect that is a tendentious estimate, considering no indicative amount of
CO2 has yet been geologically sequestered and observed for effects. The
wikipedia article has a graphic with CO2 being pumped into a "deep aquifer".

~~~
semi-extrinsic
Well, we've had the Sleipner CO2 injection in the North Sea going since 1996
at close to 1 million tons per year, with extremely close monitoring including
4D seismic. There's hundreds of scholarly articles out there with field data
and modelling of that case. I think we have some pretty good estimates of how
it works by now.

~~~
strainer
Thankyou, then that is one useful test project. I hold doubts towards what
seems to be mostly oil company sponsored research. It is one thing to have
estimates for massive geological capacity for CO2 storage, a different thing
to claim that capacity exists and that an environmentally sound industry could
be developed to fill those, seismically sensed, deep subterranean
environments.

------
mchannon
I get the desire to turn biomass into vehicle fuel. I don't get the desire to
involve hydrogen.

Biomass-derived syngas has to be substantially better in energy density and
efficiency than any kind of hydrogen.

The leading industrial use for hydrogen is in oil refining, so if you
outcompete conventional steam reformed hydrogen on price, you're just going to
make gasoline cheaper.

~~~
chimere
(Charm Co-founder here) Ultimately our goal is large-scale CO2 removal and
sequestration with biomass. This process produces an excess of energy which we
can sell in various forms to fund the process. We chose to start with Hydrogen
simply because it's quite easy and has a large industrial market.

Also note that the largest use of hydrogen (~50%) is actually for ammonia
production as fertilizer, which alone is responsible for 1-2% of global CO2e
emissions. Decarbonizing that industry would be fantastic.

~~~
mchannon
According to Dept. of Energy:

US annual hydrogen production is approximately 10 million metric tons (1.0E+10
kg), 68% of which is used in petroleum processing.

Given that worldwide production of hydrogen-derived ammonia is 140 million
tons in total, compared with hydrotreated gasoline coming in at about 2000
million tons worldwide, it doesn't appear that the U.S. is an outlier.

Decarbonizing the fertilizer industry _would_ be fantastic. Wind-powered and
solar-powered electrolyzers are already starting to do that job, perfect uses
for intermittent energy sources. I'm skeptical that your process can
realistically make more fertilizer than it consumes.

I find it a little disturbing that you boast "Hydrogen's quite easy" with this
little public documentation to back up your claims. Be real careful here: you
don't want to be the next Theranos.

You have lightning trapped in a bottle because of your luck in landing a YC
slot. I encourage you to consider pivoting technologies away from anything
involving hydrogen. Since you're such a big fan of ammonia, why not just go
straight for that? Getting your nitrogen from the plant instead of from the
air might stand a better chance to beat Haber-Bosch.

~~~
pkrein
Charm co-founder here...

(1) electrolysis is much more expensive than steam methane reformation, so
unfortunately I don't think it's gaining much steam as a real hydrogen
production method.

(2) typical ammonia fertilizer application is 0.125 tons/acre/year at a price
of $500/ton = $62.50/acre/year. Our grass and gasification process yields
$1,750/acre/year worth of hydrogen... so roughly a 28:1 financial return on
the fertilizer input which is probably pretty close to the EROI (Energy Return
on Investment)

(3) To clarify "hydrogen is quite easy"... not on an absolute basis (which is
quite hard), but relative to other products that could be produced. For
example, you mention ammonia, but ammonia production has enormous economies of
scale benefits from complex compression systems and pressure chambers... if
you run the math it doesn't work out as favorably as hydrogen, and it's
substantially more complex and difficult.

(4) We are funded by an amazing group of angel investors, but that does not
include YC.

~~~
mchannon
(1) You should check out [https://wcroc.cfans.umn.edu/wcroc-news/ammonia-
wind](https://wcroc.cfans.umn.edu/wcroc-news/ammonia-wind) (the title
specifically mentions "gaining momentum"). (Bear in mind this technology works
by making H2 first from electrolysis). There's a half-dozen more of these
research groups. Wind and solar electrolysis are sensible because they can be
placed next to ammonia consumers that currently have to have ammonia shipped
in from thousands of miles away. Unfortunately, your technology is tied to CO2
injection wells, which aren't all that common outside the western US.

(2) I'd love to see your math, but assuming it's not available, let me show
you my math: Assume 6000 pounds per acre per year yield of wet grass. Say
that's 5000 pounds dried. Model grass as 100% cellulose, which is 6% by weight
hydrogen. Assume 100% process efficiency, where you get all the hydrogen out,
and it's magically compressed. 300 pounds of hydrogen sounds like a lot, but
according to wikipedia, is only worth about 32 cents a pound at the pipe. So
my numbers show $100/acre/year. The value goes way up at the "pump", but
that's because of transportation infrastructure that neither you nor your
competition provide. That also assumes free injection of low-pressure waste
CO2, which is not only a fantasy, but presumably ties your process to a
location far away from your target market for the H2.

(3) Ammonia solves your hydrogen storage and transmission problem, so my math
shows it's way favorable, especially since you're triply tied to a CO2
injection site, fertile acreage to grow your grass, and an H2 consumer.
Picking ammonia makes cost-effective transportation to the consumer possible.
Realistically, you'd react the ammonia with CO2 to make urea, which is way
better than ammonia for both transportation costs and market demand.

(4) Didn't say YC funded you, but you were in their demo day, hence my mention
of the YC slot.

~~~
pkrein
(1) When we investigated this last year the ammonia synthesis capex looked
untenable and we didn't see a path to lower that capex. Re:injection wells...
they are super common in Texas/Louisiana region as well, which happens to be
where most of the US refining capacity and ammonia production is located, so
we're very near customers there.

(2) 6000 dry lbs/acre/year = 3 dry tons/acre/year which is an extremely low
yield. Even miscanthus and switchgrass get over 10 dry tons/acre/year, energy
cane gets to 20 dry tons/acre/year and our grass gets to 25+ dry
tons/acre/year. So that brings your $100/acre/year up to $800+/acre/year. Then
for the chemistry it's important to note that much of the hydrogen gas
produced is actually coming from H2O that reacts with carbon in the cellulose
to produce 2 H2 + CO2. So, stoichiometrically you get significantly more than
the elemental hydrogen content of the grass itself. That gets you another
factor of 2 or so... and then we're at the $1750/acre/year mentioned in the
parent comment.

(3) Agreed the transportation costs are better for ammonia, but we aren't
actually transporting the hydrogen except over a feeder pipe into a refinery
or ammonia plant. It's cheaper and simpler to transport the grass as opposed
to the hydrogen, mostly because you get to avoid the pre-transport compression
energy and losses. Again, as in (1) the issue with ammonia is the heavy capex
based around Haber-Bosch pressure vessels and compressors... we didn't have
any good ideas for reducing those costs, so there's no sense in competing
there.

(4) We weren't at YC's demo day... not sure what you're referring to
¯\\_(ツ)_/¯

~~~
mchannon
(1) Since you're limiting yourself to the gulf region, it'd probably be
responsible to disclose your CO2 injection costs, including the cost of
compressing the CO2 to the necessary pressures. It'd also be responsible to
either disavow or embrace enhanced oil recovery vs. other injection
approaches: you're either devoted to reducing carbon or making gasoline
cheaper, and you have to choose.

(2) If these numbers are accurate, you're doing yourself a disservice by
burying them. 25+ dry tons/acre/year is amazing. And I thought the crab grass
on my lawn grew fast. I seriously doubt your chemistry, however. Let's look at
your three possible approaches (2b sounding the most like what you're claiming
to do):

(2a). Charring: Hopefully using all that free low-grade heat from the refinery
you colocate with, the cellulose cooks until all the hydrogens join with the
ample oxygens in the cellulose and you end up with a char and steam. No
hydrogen this way.

(2b). Steam Reforming: This tech works with natural gas because the C:H ratio
is so low, and no oxygen is introduced that doesn't bring its own "dates".
Because the C=O bond in carbon monoxide is so strong, you can leach off some
of the H2. However, as soon as you raise that C:H ratio, or up the available
oxygen, steam reforming fails and just becomes combustion. C:H in cellulose is
6:10 vs. methane's 1:4. And that's before the 5 oxygens (vs. methane's 0) ruin
it further. No hydrogen this way.

(2c). Fischer-Tropsch (the original Hans and Franz): In a chamber about as
expensive as your Haber-Bosch capex, you somehow convert dried grass and
catalyst to a mix of H2 and CO, the latter of which you can convert into more
H2. Doesn't sound like you're using this approach, though it could technically
work if pressure cooking your grass didn't require ridiculous amounts of
energy, and you had a way to separate the H2 from the syngas. How many MJ of
energy is that? So, maybe Hydrogen this way.

(2d) What'd I miss?

(3) Ok, so your co-founder's protestations about making gasoline cheaper were
unnecessary, and you co-locate with oil refineries. Instead of downplaying it,
own it: grassoline is trademarked but not for the type of product you'd make.
Makes sense to leverage someone else's existing capex, as long as they let
you. Those oil guys are flush with cash, why are you distancing yourself from
them? They'd love to have your CO2 if it's at high enough pressure.

(4) My mistake. Your timing was highly coincidental with Demo Day, technology
looked like it could have been part of it, and the faulty assumption was mine.

------
ars
This article is about getting chopped up grass to flow through a hopper (so
that it can be gasified for fuel).

If you want to read it don't get stuck at the top (the start makes it seem
like the article is about gasification instead), keep going till the images
start.

Side note: From read this article they desperately need some experts. They are
re-solving solved problems, and not working on what their startup is actually
about. (I should add that them seem to be aware of this.)

~~~
caymanjim
> Side note: From read this article they desperately need some experts. They
> are re-solving solved problems, and not working on what their startup is
> actually about. (I should add that them seem to be aware of this.)

That was my thought as well. These guys may have a viable business idea, but
they don't appear to have any engineering experience at all, nor do they
appear to understand that one can research for existing solutions, or
hire/consult with experts. It doesn't bode well for the entire enterprise.

~~~
iso1337
Looks like they forgot to proof read their website too.

"If you are want to consume carbon-neutral hydrogen, please reach us at
sales@charmindustrial.com"

I wish them the best of luck, but I've seen the first wave of biofuels fail
and pivot to selling cosmetics or go under (Amyris, Solazyme, LS9). Sure, this
is different, but the economics haven't really changed. It's damn hard to
compete against something you can pump out of the ground and has no price tag
on its externalities.

Personally, I think more effort put into lobbying and activism is better
spent. I know we have the technology to make carbon-neutral fuels. I sincerely
hope that we transition to using something like EVs for all ground-based
transport and biofuels for applications like jet travel that need the energy
density.

However, it's the market and the economics that don't work out. And they don't
work in a way that prevents you from having easy stepping stones to scaling
up. There's basically no-one who will buy this commodity at small scale for a
much higher price. You have to succeed completely or fail.

You can even look at startups using conventional approaches and cheap
feedstock (Siluria with methane). 10 years and still working on their tech.
These big commodity markets have huge players who have huge competitive
advantages.

~~~
ars
Hydrogen is a mistake anyways, they should make syngas instead.
[https://en.m.wikipedia.org/wiki/Syngas](https://en.m.wikipedia.org/wiki/Syngas)
and then Substitute natural gas (SNG)
[https://en.m.wikipedia.org/wiki/Substitute_natural_gas](https://en.m.wikipedia.org/wiki/Substitute_natural_gas)

And if you check the articles people already make those. I guess their "new
thing" is using grass? switchgrass is usually considered the best plant for
this.

I don't really understand why they are reinventing things that already exist.

------
mojomark
In case anyone is curious as to how bio-gassification compares to electrolysis
(or a hybrid process), I found this 2009 paper [1] that sums it up decently
(at least with the technology available at the time):

(Note: SEK := Swedish Krone; currently ~$0.11USD and was roughly the same in
2009)

Abstract: "An integrated system for the production of hydrogen by gasification
of biomass and electrolysis of water has been designed and cost estimated. The
electrolyser provides part of the hydrogen product as well as the oxygen
required for the oxygen blown gasifier. The production cost was estimated to
39 SEK/kg H2 at an annual production rate of 15 000 ton, assuming 10% interest
rate and an economic lifetime of 15 years. Employing gasification only to
produce the same amount of hydrogen, leads to a cost figure of 37 SEK/kg H2,
and for an electrolyser only a production cost of 41 SEK/kg H2. The
distribution of capital and operating cost is quite different for the three
options and a sensitivity analyses was performed for all of these. However,
the lowest cost hydrogen produced with either method is at least twice as
expensive as hydrogen from natural gas steam reforming."

In addition to a dollar-to-dollar comparison, however, I think a Carbon-to-
Carnon byproduct comparison is also warranted. If you don't have to pay for
geo-sequestration (or the messy supply of grass compared to piped in water),
is the small cost increase of electrolysis over bio-gas more than compensated
for?

As an H2 advocate myself (as an industrial transportation battery
alternative), actively looking to boost H2 fuel supply infrastructure, I would
be interested to hear from Chimere (OP co-founder) on this point. I ask,
because I don't know the answer.

1.)
[https://www.sciencedirect.com/science/article/pii/S036031990...](https://www.sciencedirect.com/science/article/pii/S0360319908014481)

~~~
chimere
Interesting question - I'm not sure I know the answer but happy to speculate.
Electrolysis certainly is a much tidier process than gasification, but
everyone seems to assume it's powered by 100% renewable energy. What
incentives exist to make H2 production decarbonize faster than the rest of the
electricity grid? I'd expect electrolysis to only be fully carbon-neutral when
the rest of the grid is, which will take some time.

On the other hand, our process is close to carbon neutral from day one (we've
confirmed this with an external life cycle assessment), and will become
significantly carbon negative when we begin sequestration. And as I mentioned
elsewhere, sequestration is the primary mission and electrolysis is
unremarkable at it :]

~~~
mojomark
Thanks for the response!

So, my point is that in the bio-gas process, you are generation H2 + CO2 and
using some proceeds from H2 sales to sequester the CO2 you produce.

However, with electrolysis (from renewable elect. plants), you aren't
generating any CO2, so any profit that you spend on Carbon sequestration (from
somebody else's process) would be a much more Carbon negative proposition
overall.

All this depends on the H2 production cost as to which is a mor effective
Carbon sequestration scheme, right?

In the paper I cite (I convert SEK to $): bio-gas costs ~$4/kg H2 (let's say
this produces 5 kg of CO2), and electrolysis ~$4.50/kg H2 (producing 0 kg
Carbon).

Now say it costs $0.50/kg for CO2 sequestration). In the biogas process,
because of the cost to sequester the CO2 byproduct, your actually spending
($0.5×$5)+$4 = $6.50/kg H2 produced just to get Carbon Neutral. However, for
electrolysis (without the mess) you're only spending $4 to be Carbon Neutral,
and if you want you can spend $2.50 (which you avoided by chosing elect. over
gas), to go Carbon negative.

These are rough numbers I guessed at based on a little googling. Am I far off
on the real numbers?

I'm really not trying to be a pain. What you're proposing is still light years
better than the greedy bastards reforming natural gas and pocketing 100% of
the profits without giving a second thought to the environment. I'm just
wondering if there might be a way for you guys to do even more good, more
easily.

~~~
pkrein
The economics you're looking at for biogas and electrolysis look roughly right
to me. But our models suggest that thermal gasification of biomass can get
down to $1/kg. So then you're looking at $4.50+/kg for electrolysis or $1/kg
for gasification... and you can see how all that math changes.

Electrolysis also typically costs more than you'd expect as soon as you add
the requirement of renewable energy supply. Usually the renewable energy
supply is solar, which has a ~30% duty cycle. So 70% of the time your
electrolyzer is sitting idle. This _crushes_ your economics and makes solar-
powered electrolysis untenable in all of the analyses I've seen. We didn't
have any clever ideas for how to change that situation, so after looking at it
~1.5 years ago we decided to look elsewhere.

~~~
mojomark
Good answer, thank you. Like I said, it all boils down to the cost of H2
production for a given process. If you have a path to get to $1/kg H2, that is
truly awesome!

Working very peripherally in this sector, I applaud your efforts, not only for
the ingenuity, but also for the guts to consider environmental impact as
opposed to stock-holder happiness from a profit margins perspective.

Honestly, it would be cool if on your site you showed a side-by-side
comparison on your profit model compared to a competing natural gas reforming
competitor's profit structure to demonstrate to customers how you are
sacrificing some profit for environmental benefit, whereas the competition
simply pockets the profit and turns a blind eye to the environment. For me,
that would help me decide to buy potentially higher cost H2 from you, just
like I choose to pay a higher premium for energy I know is renewable sourced.

The world needs more innovators like you folks. Good luck!

------
zawerf
I remember seeing a video demoing how to make sand flow like water by bubbling
air into it:
[https://youtube.com/watch?v=My4RA5I0FKs](https://youtube.com/watch?v=My4RA5I0FKs)

~~~
chimere
(Charm co-founder here) I love that video! That fluidization phenomenon is
commonly used in large-scale gasification or combustion processes, see:
[https://en.wikipedia.org/wiki/Fluidized_bed_reactor](https://en.wikipedia.org/wiki/Fluidized_bed_reactor)

~~~
mojomark
You probably know, but don't forget that compressing air is energy intensive.
I'm not saying that the extra expense can't be marginalized - especially if
you can dramatically increase production, I'm just pointing out that it's far
from free. Just another fun engineering problem to tackle:)

------
cwkoss
I was just talking with a coworker about how we could theoretically modify our
espresso machine hopper to avoid blockages. This is a great survey of bulk
material handling options.

------
gus_massa
How advanced is the hydrogen production prototype?

Looking at the Wikipedia page
[https://en.wikipedia.org/wiki/Steam_reforming](https://en.wikipedia.org/wiki/Steam_reforming)
this looks like a difficult process, even when using methane that is a very
small molecule and is easy to purify. Big molecules in grass are more eager to
produce soot that would block the machine, and grass also has other elements
like Nitrogen and Phosphorus that may react with the catalyzer, and there is
the ash problem.

Is using a grass more efficient that burning the grass and use the energy to
produce Hydrogen with the standard method?

What about producing ethanol from the grass and then using the ethanol to make
the Hydrogen? (Both parts are somewhat proven technology.) And ethanol is easy
to move and purify than grass.

------
jacknews
"With the addition of geological carbon dioxide sequestration it becomes
carbon-negative."

LOL, easy peasy then

Can you make "grass charcoal"? If so, just pile the grass high and cover in a
layer of clay before burning, as is done with wood. Then bury the charcoal,
which also improves the soil

~~~
chimere
(Charm Co-founder here) Certainly - you're effectively describing biochar
([https://en.wikipedia.org/wiki/Biochar](https://en.wikipedia.org/wiki/Biochar))
which historically has been used as both an energy source and a soil
amendment. Using it as a sequestration method has gained some attention
recently, though I have reservations.

For one, biochar is typically produced in small, low-efficiency reactors
without proper emissions control (though this is solvable). The bigger issue
is the high energy content of biochar (~30MJ/kg). Simply burying all of this
energy isn't economical - it makes much more sense to store carbon in its
oxidized state, and sell the energy that's released in the process (in various
forms - we're starting with Hydrogen).

~~~
marvindanig
Did you try blowing air through the mass from bottom up? It can help loosen
the grass chips, reduce moisture and prevent agglomeration and is useful as
long as the air flux doesn't prevent the grass from funneling down.

~~~
chimere
Certainly we considered it. The problem is that on this prototype system we
were operating with a sealed hopper. Thus any gas injected into the hopper
would travel through the system and dilute our output gas stream. Also any
oxygen in the injected gas would result in combustion rather than
gasification.

~~~
marvindanig
The inside of the funnel can be lined with a tube punchered uniformly and use
pneumatic nitrogen piped from above and outside of the sealed hopper? I’m
getting these weird ideas in my head.

~~~
marvindanig
punctured^

------
malloryerik
If you want to have the grass flow like water, could you take a stream of
water and add grass to it? The water could carry it down a wide pipe for
example, you filter the grass from the water at the destination, then send the
water back to get more grass?

~~~
torpfactory
Things start happening to grass when you put it in water. That might be OK
depending on your other processing steps. A similar idea is pneumatic
transport, where you add material to an air stream and then use a cyclone to
separate the air and the grass.

------
gdpgreg
Looks like the issue is the feed stock, non-uniform particle size distribution
and significant differences in aspect ratio. All the different pieces are
clumping up because of the particle interlocking. Maybe consider a grill
sorter on the outlet of your size reduction system, allow <1cm particles
through and rehandle larger particles back into whatever is chopping, or add
secondary size reduction.

------
NoblePublius
Where is the evidence that carbon sequestration works?

~~~
pkrein
Stanford Prof. Sally Benson's talk here is a great overview:
[https://youtu.be/lIVwbSnD0AI?t=127](https://youtu.be/lIVwbSnD0AI?t=127)

Specifically, she talks about the results of the Sleipner Project in the North
Sea, where they've measured leakage rates, etc:
[https://youtu.be/lIVwbSnD0AI?t=1199](https://youtu.be/lIVwbSnD0AI?t=1199)

~~~
NoblePublius
Still seems like this is a big guess that sequestration works over long
periods, or at all at the scale necessary to be industrially significant. I’m
inherently sceptical of anything hydrogen related due to the fuel’s
association with delay tactics from the carbon industry. Chevron would prefer
we all not buy electric cars in hopes of HFC becoming a real thing which,
obviously, is just a farce to keep paying them to produce, transport, and sell
solid fuel. I think we are better off as a society not burning carbon at all,
not looking for places to put carbon polution.

~~~
pkrein
Charm co-founder here... We are not betting on hydrogen fuel cell cars. There
is an existing $120B/year market for hydrogen used in the production of
ammonia fertilizer and oil refining. That hydrogen is currently produced from
fossil natural gas, and we are replacing that.

The Sleipner Project for geological carbon sequestration has been ongoing for
20 years with extremely rigorous measurement. We also know that natural gas is
stored in geological deposits for millions of years, and in _vast_ quantities.
I don't see a strong reason to be skeptical of long-term sequestration a
slightly different gas in those same geological formations.

~~~
NoblePublius
Natural gas wasn’t injected down there by man. I can tell you’re sincere but
those are not the same things. This still seems like a giant guess. We’re
better off burning as little carbon as possible.

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hourislate
Couldn't they use a manure spreader to throw the grass onto a conveyor belt at
a steady rate? Manure spreaders come with variable flow rate and beaters to
shred the manure. If you threw a bale of hay in there it would tear it up and
throw it nicely.

Here is an example:

[https://www.youtube.com/watch?v=YhvMMK91P-8](https://www.youtube.com/watch?v=YhvMMK91P-8)

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vlizz
Is there a reason you need to make it flow as opposed to simply conveying it
mechanically? It seems like you came up with a complicated solution (making
solids behave like liquids) when there are plenty of simpler solids handling
techniques that could be used. For example a belt or screw conveyor.

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L_226
I like this. Slightly related, I am planning on building a house eventually
and I really want to incorporate a domestic biogas generator for cooking.
Something like [https://www.homebiogas.com/](https://www.homebiogas.com/)

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snappr_
Can the ash be used as a concrete additive?

[https://precast.org/2010/05/using-fly-ash-in-
concrete/](https://precast.org/2010/05/using-fly-ash-in-concrete/)

~~~
pkrein
Charm co-founder here... possibly, but it's likely more valuable being sold as
potash.

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dosy
you want to mix the grass with air so you have grass suspended in a flow of
air just like a fluid. since you need to avoid oxygen blow this grass nitrogen
suspension through some pipes and into your gassifier.

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vixen99
'Charm’s mission is to return the atmosphere to 280 ppm CO2 profitably'.

i.e., 2,130,000,000 metric tons of CO2 (= 1ppm) * (410ppm - 280ppm) or some
276 giga tons. Evidently a modest goal.

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metalgearsolid
I would have loved to be there the moment they first tried a funnel and
failed. Bulk material handling seems pretty interesting to solve.

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SubiculumCode
I wonder what dampening the grass might do, as this might reduce the volume of
the grass (increase density).

~~~
rtkwe
First guess is it'd make it mat together worse by adding surface tension into
the mix.

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ggm
what % of the generated H2 is currently consumed by the sequestration?

If no other energy source is available, does this % change?

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mrfusion
So how does the sequestration work?

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trickstra
wouldn't it be easier to pelletize the grass before feeding it?

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naringas
why not blow the grass?

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kazinator
> _Naively, we assumed that grass would flow somewhat like an ideal fluid,_

Perfect sustenance for spherical cows.

> _allowing us to use a simple, funnel-like hopper._

But, since that one didn't vibrate, it could hardly be called a grasshopper.

~~~
dsfyu404ed
>Perfect sustenance for spherical cows.

Engineering students discover that real world specialized solutions are in
fact optimized for what they do. Water is wet. More breaking news at 11.

