
'Bath sponge' breakthrough could boost cleaner cars - fpoling
https://www.bbc.com/news/science-environment-52328786
======
gok
It's a novel way to store hydrogen instead of a traditional high pressure
tank.

This is a teeny tiny problem for a hydrogen cars. It doesn't really address
the problem that fuel cells are ridiculously expensive, or that there's no
filling network, or that there's no good way to fill them at home, or that
fuel cells are themselves only 50% efficient typically.

~~~
gpapilion
I’ve always thought the distribution issue it’s the largest problem for
alternative fuel vehicles.

Driving to Los Angeles from San Francisco is extremely difficult for either a
fuel cell or ev vehicle (that’s not a Tesla, and it’s also true for cng
vehicles). This is admittedly not a daily use case, but highlights the issues
with refueling.

It’s hard to see either technology being our primary transportation mode
without solving some of this. EVs have an advantage for fuel availability, but
issues around fueling time.

~~~
halfdan
I think there's a common misconception in your argument. Even without a full
distribution network it might be a viable solution. Most of us use our cars
for our daily commute, grocery shopping and other things within a fairly small
radius. The few times we would need to drive the SF->LA distance you can
easily take a rental.

The mistake is to assume that we would use "alternative fuel" vehicles the
same way we would our petrol cars.

~~~
greglindahl
I don't think there's an assumption there. The alternative fuel cars that sell
well are the long-range ones. Sure, people mostly drive them locally, but it
appears to be the case that there's comfort in knowing that they can also go
long distance.

~~~
rootusrootus
I think 300 miles is a realistic minimum for viable EVs. At least in America.
Because honestly, almost nobody gets anywhere near that except when they're
trying to win Internet points. A 300 mile Tesla Model 3, depending on trim, is
more realistically a 150-200 mile car, and some days won't even make it that
far.

Source: I own a Tesla Model 3 Performance. For efficiency, the worst of them.
Love the car, but saying it has 300 miles of range feels pretty dishonest.

------
credit_guy
Summary for those who didn't click on the link to the actual article [1]:

\- a car may need 5 kg of hydrogen for a range of 500km (bbc's claim, I'll
take it at face value)

\- the new "sponge" material can offer "deliverable hydrogen capacities (14.0
weight %, 46.2 g liter−1) under a combined temperature and pressure swing (77
K/100 bar → 160 K/5 bar)."

\- so for 5kg of H2 you need about 100 l of this material, at a weight of
about 35 kg. Not too shabby.

\- however, note the conditions: you store the H2 at 77k and 100bar. So you
need liquid nitrogen and quite high pressure to hold this. That might add
substantial weight to the 35kg of sponge

By the way, about one year ago, there was quite some big noise on HN about a
different breakthrough from Australia, where some researchers showed economic
ways to store H2 in ammonia. Not sure if that got anywhere.

[1]
[https://science.sciencemag.org/content/368/6488/297](https://science.sciencemag.org/content/368/6488/297)

~~~
jessaustin
Liquid anhydrous ammonia is already the obvious way to store and use hydrogen.
It contains lots of hydrogen but doesn't have the embrittlement issues that
elemental hydrogen does. Agricultural regions have extensive storage and
distribution capacity due to its use as fertilizer, so no new technology is
needed for handling ammonia. Common internal combustion engines can burn
ammonia as fuel with minimal modification.

The only thing holding back the use of ammonia as energy storage is the fact
that fossil fuels are still the most efficient feedstock. Once solar is more
efficient, ammonia will see widespread production and use.

~~~
m463
Also it's a dangerous material to spill.

~~~
entee
Very much so. Would be hard to breathe at any accident site with a leak.

~~~
rstuart4133
But not quiet as hard to breath as 60 litres of petrol, going up in a ball of
flames.

~~~
CamperBob2
Which doesn't happen in the real world because of the way fuel tanks are
constructed. Meanwhile, anhydrous ammonia is one of those things that give
experienced hazmat workers nightmares.

~~~
jessaustin
Most of the people who safely use anhydrous ammonia on a regular basis are
farmhands, not experienced hazmat workers. The training and equipment that
allows them to do that would also be available to e.g. municipal bus lines or
delivery companies. Any firm that hires people to refuel its vehicles could
afford this. Eventually more fool-proof nozzles and storage tanks might be
developed so that regular people with personal cars could safely handle this
fuel, but it will be practical for other uses long before then.

~~~
CamperBob2
Interestingly, the last time I heard an argument like this, it was being put
forth in favor of using butane or propane as a replacement for CFC
refrigerants in cars. That idea never caught on, but it's not clear if safety
concerns in accidents were the reason.

At any rate, unless Farmer Brown regularly drives his fertilizer sprayer
around on the farm at 70 MPH, I'm not convinced your analogy holds much more
water than the anhydrous ammonia does.

Hydrogen is best thought of as an energy transfer mechanism -- an extremely
lossy one at that -- not an energy source, and I don't see that changing
anytime soon. It's hard to believe that ammonia-based storage is the missing
factor in the hydrogen equation that we've all been searching for.

~~~
jessaustin
You have inconsistent fears. Presumably you mention 70mph because you're
afraid of explosions from vehicle collisions. Yet ammonia is much less
flammable (NFPA 1) than gasoline (3), and much much less flammable than
elemental hydrogen (4). Ammonia is regularly used as a refrigerant and has
been for longer than CFCs have existed. It is poisonous, but no more so than
many gasoline additives and less so than tetraethyllead, which was a common
additive until quite recently. More to the point, when burned in an engine it
produces nitrogen and water, which are much safer than ICE exhaust.

No one is proposing hydrogen or ammonia as an energy source. There are no
underground deposits. They will only make sense once solar generation is
efficient enough that electrolysis becomes competitive with fossil fuels.
We'll know that's coming soon when hydrogen hype artists are drowned out by
engineers talking about ammonia.

------
bcatanzaro
Hydrogen storage may be useful in the future. But probably not for cars.
Battery EVs are better environmentally (much lower carbon footprint and higher
efficiency), have longer range and more power.

It’s too bad the story had to be written about car applications rather than
the MOF itself.

~~~
Hypx
I beg to differ. You still need an absolutely massive amount of raw material
for batteries. This is it’s own environmental problem unrelated to climate
change. Fuel cell cars can easily have 500km+ ranges and upwards of 900hp if
you really wanted that much power. Not sure how you can argue this point at
all.

------
wishinghand
This is good research for low-pressure hydrogen storage, but I think pursuing
hydrogen powered cars is folly. It still has to be mined or generated,
refined, and transported to filling stations, whereas with electric cars the
transport and filling network is already in place. It's still a middleman to
lose efficiency that electric cars don't have.

~~~
erik_seaberg
Hydrogen could be a win if we can get it into the tank in a couple minutes.
Very few apartments or workplaces have EV chargers so far, and it's
impractically slow to do anywhere you weren't planning to park for a long
time. A Tesla Supercharger station would have to be 10x as big as a gas
station to accommodate the general public stopping for a half hour each for a
partial charge, assuming they would put up with the wait.

~~~
greglindahl
You could have made the same comment 6 years ago, and behold, lots more people
drive EVs today than 6 years ago.

There's been a lot of progress in cajoling and requiring apartment complexes
and workplaces to install chargers, and Tesla has a lot more superchargers
(mostly in mall parking lots) than they used to have.

So it sure doesn't seem like there's any insurmountable problem involved that
would cause us to stop promoting EVs.

Meanwhile, hydrogen fuel cells haven't fallen in price like Toyota predicted,
and so their hydrogen car is both expensive and low performance. Not a winning
combination, even if it fuels up in 5 minutes.

~~~
Hypx
I’d say you just aren’t paying attention to the gains being made in fuel cell
technology. A lot of people on this website are really oblivious to this, so
you’re not alone.

The 2021 Mirai using only 10 grams of platinum. Although they haven’t spoken
much about pricing, it’s pretty obvious this is going to be a cost effective
car to manufacture. Certainly, it’s going to be a lot cheaper to produce than
a car with 600kg of batteries.

The upcoming BMW X5 Hydrogen is going to have 370 hp. I’d say that’s plenty.

~~~
greglindahl
Uh, OK. We're N years into the Hydrogen Revolution and the only problem is
that people are ignorant?

It was the 2017 Mirai that was supposed to be powerful and cheap. Now it's
2021. The old model had 151 hp. The new one has... ? neither a price nor a
performance?

The low end gas X5 has 335-456hp. So far the BEVs that have sold well have
much higher performance than the minimum.

~~~
Hypx
It's not a function of time but rather progress. Since there has been
significant progress (mostly ignored by the tech community), the commonly used
arguments against hydrogen are now wrong.

They haven't announced those numbers yet. We know BMW is building an X5 with
368hp using Toyota's fuel cell stack: [https://www.topgear.com/car-
news/electric/bmws-hydrogen-x5-w...](https://www.topgear.com/car-
news/electric/bmws-hydrogen-x5-will-produce-368bhp)

So we should be reasonably sure the new Mirai is going to be much faster than
the first. It's also going to have around 400 miles of range and will be much
bigger and more luxurious. We haven't heard about pricing yet, but from a
production standpoint Toyota has talked extensively about how much cheaper it
is to make.

------
lowdose
Sounds like an artificial zeolite.

[https://en.m.wikipedia.org/wiki/Zeolite](https://en.m.wikipedia.org/wiki/Zeolite)

~~~
jkqwzsoo
It's a MOF (metal-organic framework). Basically a metal ion or metal cluster
linked (nodes) together with organic molecules (linkers or struts). Some of
them are even stable in aqueous solutions (like UiO-66). Typically, the
linker-metal bond is via a carboxylic acid, and the metal node is something
like... Zr, Ce, Hf, Ti, Fe, Cu, Co, Mn, Al, etc. etc. They've been the gold
standard for gas sorption and hydrogen-car promises for at least 17 years.

The actual term MOF was apparently first used in 95[0].

While there are a lot of things that can affect the synthesis (metal
concentration, metal precursor, metal:linker ratio, solvent choice, presence
or absence of water, modulators, synthesis temperature), the synthesis of MOFs
is usually about tuning what goes into the pot. Then its shake-n-bake and MOF
comes out a day later (solvothermal method). So, it's an easy synthesis if you
know what to load into your reaction vessel. While continuous synthesis is a
harder, I think it's a lot more immediately scalable than porous aromatic
frameworks (PAFs).

This work is combining some of the advantages of MOF (high specific surface
area, regular structure, easy synthesis) with some of the advantages of PAFs
(even higher specific surface area). You can see the linker they use on PDF
page 5 of the supplementary online material[1]. The hexadentate structure is
large and is reminiscent of PAFs like PAF-1[2], which are known for having
very high specific surface area. This is because the aryl group has a high
specific surface area. By making the linker very large and bulky, they're
reducing the contribution of the metal nodes to the specific surface area by
having a greater volume fraction of (lightweight) aromatic linker. However,
while PAFs usually (always? I'm not a PAF person) have an SP3 carbon center
(and thus a tetrahedral symmetry), this linker is kind of shaped like a paddle
wheel with three paddles (or a trigonal prism, if you access the Science
article and see Fig. 1). Thus, while PAFs are typically in a diamond-like net
( _dia_ [3]), this MOF is in a _acs_ net[4].

[0]
[https://www.nature.com/milestones/milecrystal/full/milecryst...](https://www.nature.com/milestones/milecrystal/full/milecrystal22.html)

[1]
[https://science.sciencemag.org/content/sci/suppl/2020/04/15/...](https://science.sciencemag.org/content/sci/suppl/2020/04/15/368.6488.297.DC1/aaz8881_Chen_SM.pdf)

[2] dx.doi.org/10.1039/C4MH00163J,
[http://www.rsc.org/suppdata/mh/c4/c4mh00163j/c4mh00163j1.pdf](http://www.rsc.org/suppdata/mh/c4/c4mh00163j/c4mh00163j1.pdf)

[3] [http://rcsr.anu.edu.au/nets/dia](http://rcsr.anu.edu.au/nets/dia)

[4] [http://rcsr.anu.edu.au/nets/acs](http://rcsr.anu.edu.au/nets/acs)

Fun fact: Most MOFs are named after the research institution that found them
first. This one is named NU-1500 for Northwestern University, where Farha is.
The UiO-series are named after Universitet i Oslo, the HKUST series is named
for Hong Kong University of Science and Technology, the MIL series is named
for Material Insitute Lavoisier.

~~~
lowdose
Thank you for your explanation & links, much appreciated.

------
maga
I'd like to know how it compares to existing solutions, the only thing I see
in abstract is meeting/exceeding some US gov target. Can someone knowledgeable
weigh in on this? How big of progress is this?

------
mrfusion
Could this have other uses? Spacecraft?

~~~
joshuaheard
I wonder if this same principle could be used to store air for scuba tanks. It
would be an improvement over existing compressed air tanks if the tank could
be made smaller and lighter.

------
rcMgD2BwE72F
>Now, researchers believe they have developed an alternative method that would
allow the storage of high volumes of hydrogen under much lower pressure.

They'll still be 100 reasons to favor battery EVs to _renewable hydrogen_ fuel
cells. Better storage does not increase its inferior well-to-wheel efficiency.

~~~
Hypx
That’s really the only reason to favor BEVs over hydrogen. Everything else,
from weight, cost (eventually), range, raw material requirements, are better
with fuel cells.

------
jwilk
For a moment I thought it's going to be about car washing.

