'Bath sponge' breakthrough could boost cleaner cars

https://www.bbc.com/news/science-environment-52328786

by fpoling • 6 years ago

95 108 6 years ago

gok2• 6 years ago

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.

SuoDuanDao• 6 years ago

Fair enough - but as to the filling network at least, that seems a lot more feasible given a decent way to store it.

jimmySixDOF• 6 years ago

RIP Better Place (2007-2013). They were ahead of their time and if hydrogen refueling stations take off it will be following in their footsteps.

[1] https://en.m.wikipedia.org/wiki/Better_Place_(company)

jkqwzsoo2• 6 years ago

MOF-based hydrogen storage has been around since at least 2003 (Omar Yaghi on MOF-5). Its hardly a novel concept. I haven’t read this paper, I just skimmed for figure out what the “aluminum sponge” was until I saw it was Farha and MOFs. As far as I can tell, this is in Science because it surpasses key benchmarks set by the DOE, not because it’s a new idea.

This is a particularly high surface area MOF (>7300 m^2/g). I recently picked up a MOF project (not related to hydrogen storage) with derivatives of a popular MOF and it’s closer to 1000 m^2/g. Zeolites (a much more established class of porous material) are about a quarter of that (<200-300).

An actual metal sponge (what I thought the article was talking about) is <~20 m^2/g.

gpapilion• 6 years ago

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.

logical42• 6 years ago

There are enough CNG stations to drive from SF to LA as long as you fill up appropriately.

halfdan• 6 years ago

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.

goodcanadian• 6 years ago

I was surprised by your assertion that it would be difficult to drive an EV (non-Tesla) from LA to SF, so I did a quick search. It appears that there are regular charge points along I-5. I wouldn't be worried about it at all.

woodandsteel• 6 years ago

The total number of rapid charging stations is large and is increasing rapidly, while the total number of hydrogen is small and increasing slowly. It is quite certain this state of affairs is going to continue in the future, until eventually there are enough charging stations for everyone to go electric.

clouddrover6• 6 years ago

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).

Maybe true for hydrogen, not so true for BEVs. There are plenty of CCS charging locations in the US and California in particular has many of them:

https://www.electrifyamerica.com/locate-charger

https://afdc.energy.gov/fuels/electricity_locations.html#/fi...

You can try out routes using Plug Share and A Better Route Planner:

https://abetterrouteplanner.com/

https://www.plugshare.com/

San Francisco to Los Angeles is an easy drive in a Chevy Bolt, for example.

mrfusion2• 6 years ago

Good points. I’ve always been curious. Why not just plug in A hydrogen car and run the fuel cell in reverse to get a tank of hydrogen?

pmorici• 6 years ago

The only reason that Hydrogen powered cars are even still discussed over battery electric is that 95% of industrial hydrogen is produced from fossil fuels. In other words the people pushing it are probably protecting their oil and gas interests. They aren't going to put money into research to cut themselves out of the loop.

[0] https://en.wikipedia.org/wiki/Hydrogen_production

danans3• 6 years ago

Doing this would defeat the only advantage hydrogen has, which is rapid fueling. To add to the inconvenience, you'll need to plug in both the electricity, and a hose to your supply of distilled water.

Beyond that, the best case efficiency for such a hydrogen production process in an industrial setting is 80% (using a process which feeds waste heat back into the electrolysis reaction). From the hydrogen back to energy moving the wheels is at most 50% efficient, so a total plug to wheels efficiency of less than 40%. In the real world, it will be far less efficient than that (probably 25% at best), and very expensive to achieve in a practical car for sale, for the same reason that hydrogen fuel cells in cars are expensive today.

That vs the typical plug to wheels efficiency of around 60% in today's electric vehicles.

And such regenerative hydrogen fuel cells do not even exist for automotive applications today.

This paper has several lifecycle efficiency graphs that explain aspects of this in some detail:

https://www.mdpi.com/2032-6653/9/1/3

gok2• 6 years ago

One issue is that you need a source of water. Another is that electrolysis is only around 70% efficient, whereas (say) lithium ion battery charging is more like 95% efficient.

gryzzly• 6 years ago

Or that pollution from tires is a serious problem and SUV-level weight moving at high speeds is not something we need more of.

kevin_thibedeau• 6 years ago

Most "SUVs" are just station wagons with an extra inch of ground clearance. They aren't that heavy. A Prius, on the other hand is close to the weight of a light truck.

zaroth• 6 years ago

I’m sorry but this is basically just flame baiting. Just tossing in a zealous attack against large cars in the middle of a discussion on fuel cells... What is the interest in rehashing that same old debate in this thread?

Hypx15• 6 years ago

Basically everything you said is wrong. The costs of fuel cells are dropping so fast, that that is probably the main driver of interest in fuel cell technology recently. The filling stations are being installed by dozens around the world right now. Fuel cells have reach 60% efficiency in real world testing.

It’s been something of a blind spot among tech workers that they are completely oblivious to the gains made in fuel cells. For all the hype about us being forward thinking, a lot of us are seriously stuck in the past.

casion• 6 years ago

OP mentioned things that exist now, your response seems to be that things are improving.

Those ideas aren't at odds.

reissbaker3• 6 years ago

It's not much of a blind spot. Fuel cells are worse for consumer cars than batteries, both in environmental terms and in terms of convenience. A BEV can recharge at home using existing standard outlets (a 240v 30A or 50A dryer outlet for good performance, or even a 120v regular outlet will do if you're willing to wait a while); good luck refilling a fuel cell.

BEVs are nearly 80% efficient already [1], are comparatively widely deployed, and the infrastructure for them exists in everyone's home. For long distance travel, there are far more fast chargers than hydrogen stations, and far more investment in building more of them.

Also, most independent real-world tests I've seen of hydrogen cells reported much lower efficiency in practice than claimed — often between 30-40%. The only tank-to-wheel 60% claim I could find was a statement by Honda of their own car; FWIW, the EPA rating of the latest, most-efficient version of that car (the Honda Clarity Fuel Cell) is actually 68 MPGe [2], which is much lower than most BEVs. In fact, the battery-based version of the same exact car, the Honda Clarity EV, has an EPA rating of 114 MPGe [3], which is nearly 70% more efficient.

Hydrogen fuel cells for consumer cars just don't make sense.

1: https://www.fueleconomy.gov/feg/evtech.shtml

2: https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=40044

3: https://www.fueleconomy.gov/feg/noframes/41185.shtml

rcMgD2BwE72F• 6 years ago

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.

Hypx15• 6 years ago

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.

maga• 6 years ago

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?

bcatanzaro• 6 years ago

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.

Hypx15• 6 years ago

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.

credit_guy• 6 years ago

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

greglindahl11• 6 years ago

The main utility for ammonia is to transport energy long distances at industrial scale, not for individual vehicles.

So, for example, you'd build a huge solar farm where it's very sunny, or a huge wind farm where it's windy. And instead of running power lines, you'd ship ammonia.

jessaustin4• 6 years ago

Power lines are cheaper and more efficient than pipelines, and they always will be. Ammonia will be a storage medium.

rstuart41333• 6 years ago

The main utility for ammonia is to transport energy long distances at industrial scale, not for individual vehicles.

Which is exactly how it was pitched in Australia, by the government agency responsible for developing it. It was the reason it was funded.

As I recall, it was "it solar continues current downward trajectory, it will be cheaper make than it is to frack natural gas". They seemed pretty convinced of it.

jessaustin4• 6 years ago

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.

m4632• 6 years ago

Also it's a dangerous material to spill.

mhandley• 6 years ago

The Royal Society's policy briefing report on Green Ammonia goes into all this in detail, and makes the case pretty well:

https://royalsociety.org/topics-policy/projects/low-carbon-e...

rstuart41333• 6 years ago

Grrrr. It's efficiency is based on using a fuel cell. There seems to be a few ways around of storing Hydrogen in clever ways - this just adds to the list. But until we discover unobtainium that's as efficient as platinum in fuel cells but common and a fraction of the price, it's all a pipe dream.

Had they burnt it in an ICE, and come up with those figures then OK. As it is, when using technology that exists now it won't be 5 kg per 500km, it will 25 kg at best, and 500l of this material will be required.

clouddrover6• 6 years ago

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

It is about 1kg for 100km range. The Hyundai Nexo Blue has better than 600km range on 6.5kg of hydrogen:

https://www.drivingelectric.com/hyundai/nexo/1005/hyundai-ne...

https://en.wikipedia.org/wiki/Hyundai_Nexo

mrfusion2• 6 years ago

Could this have other uses? Spacecraft?

joshuaheard• 6 years ago

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.

lowdose2• 6 years ago

Sounds like an artificial zeolite.

https://en.m.wikipedia.org/wiki/Zeolite

jkqwzsoo2• 6 years ago

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...

[1] https://science.sciencemag.org/content/sci/suppl/2020/04/15/...

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

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

[4] 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.

lowdose2• 6 years ago

Thank you for your explanation & links, much appreciated.

wishinghand• 6 years ago

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_seaberg3• 6 years ago

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.

greglindahl11• 6 years ago

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.

m4632• 6 years ago

Investing in electrical infrastructure aligns with the way the world is going -- higher consumption (not only EVs but growth in general) + higher local generation (local PV)

I expect it will just happen anyway. Meanwhile hydrogen will require all new single-use infrastructure.

jwilk• 6 years ago

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

'Bath sponge' breakthrough could boost cleaner cars

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