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New Approach to Developing Nanoporous Materials Shows Promise for Hydrogen Storage

1 January 2008

Polyaniline
SEM micrograph of hypercrosslinked polyaniline at magnification of 15000x. Click to enlarge.

Researchers at Lawrence Berkeley National Laboratory and the University of California, Berkeley have developed an entirely new type of nanoporous material—hypercrosslinked polyaniline—that shows promise as a potential storage medium for hydrogen.

The new materials have a permanent porous structure and specific surface areas exceeding 630 m2 g-1. The researchers, led by Frantisek Svec, found that the best adsorbent of the materials had a hydrogen storage capacity of 2.2 wt% at 77 K and 3.0 MPa.

Hypercrosslinked polyanilines exhibit a remarkably high affinity for hydrogen, according to the researchers, which results in enthalpies of adsorption as high as 9.3 kJ mol–1 (exothermic), in sharp contrast with hypercrosslinked polystyrenes and metal–organic frameworks which have significantly lower enthalpies of adsorption, typically in the range of 4–7 kJ mol–1.

The team made the new materials by adding small molecular crosslinkers to commercial polyanoiline that had been swollen in an organic solvent. The hypercrosslinking reaction results in a rigid, mesh-like structure.

The current materials are still from practical hydrogen stores. Even the current best-performer at 77K still falls far short of Department of Energy targets for storage system capacity. And, said Andrew Cooper, who studies hydrogen storage polymers at the University of Liverpool (UK), in a report on the work in Chemical Technology:

With what you’d have to change in structure to achieve room temperature hydrogen storage, it’s arguable whether you could still call it the same material. The key advance with this work is the new approach to make porous polymers.

The Berkeley team is currently trying different crosslinkers and different reaction conditions, to increase the material’s capacity.

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January 1, 2008 in Hydrogen Storage | Permalink | Comments (14) | TrackBack (0)

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I'll bet they'll find all kinds of other uses for these kinds of materials that nobody's even dreamt of yet.

It would be very expensive to produce a lightweight storage tank that could sustain 30 bar pressure at 77K temperature and still survive a crash. Virtually all structural materials become brittle at very low temperatures.

Perhaps DOE should stop trying to find a way to store hydrogen and instead focus on adsorbed natural gas (ANG) storage. Unlike CNG at 200-300 bar, ANG can make do with the pressures already present in the gas distribution backbone. Methane is a plentiful fossil fuel suitable for slightly modified SI engines. It is also the only biofuel that can be produced in industrial quantities from non-woody cellulosic waste today. The post-processing is expensive, but at close to $100 per barrel of oil, so are fossil fuels.

If crash safety can be assured, the adsorption material could double as soundproofing to keep total bulk and weight within reason. Initial applications could focus on trucks and buses because the ladder frame chassis usually already contains voids.

Well of course Rafael
CNG is already almost entirely hydrogen.

However the whole point of doing hydrogen is that it's SUPPOSED to be impractical.

That way they can postpone it forever, but continously look they are working on solving our transportation problems.

It would also lose much of it's hype. Consider it would have tailpipe emissions, and it would have carbon emissions.

We can't have that, now can we?

The Hydrogen storage argument was rendered moot in 2007 by new technology which separates hydrogen and oxygen quickly, efficiently and virtually on-demand from water. Turns out water is also the best, most stable, least harmful and most readily-available source of H and O on the planet. It's also quite renewable, is energy-dense, is virtually ubiquitous and significantly less expensive that processed fuels.

The question before humanity now is thus: How best to harvest the potential power from these two gases--through a fuel cell membrane or via direct combustion?

PS,

got any links for this new tech that separates H2,and O?

To your last statement - it would seem that internal combustion with its attendant inefficiencies and maintenance needs has had its day.

@ ProblemSolver -

water is burnt hydrogen. It has zero exergy (convertible energy content). Rather, you have to invest a lot of expensive electrical energy to once again split water into hydrogen and oxygen. High-temperature electrolysis can reach efficienies of 85-90% and, fuel cells can convert some 60% of the energy stored as hydrogen back into electricity to drive on-board electric motors. Ergo, it takes almost twice as much primary energy (fossil, nuclear, renwewable) to run even the most efficient vehicle on hydrogen as it does to temporarily store the electricity in batteries.

Please look up the second law of thermodynamics. No technology can ever repeal the laws of physics.

Additional point to make is the %wt. To store a measily 5 kg of hydrogen, which people want because they don't want to refuel all the time would weigh over 220 kg.

And people complain about battery weight.

Electrolysis is 140% efficient.

1 room temp electrolysis hit 85% 2 years ago and was reported on this very site.

2 High temp electrolydid is 140% bevause its using waste heatto do the lions share of the work. Now the main point here is the power company can cram 100 mw of power in get 140 mw worth of h2 and then when needed dump iy inyo a standard stationary fuel cell and get even today... 98-112 mw out again for peak loads and spot loads,, and if they have extra.. sell it for 4-3 even 1 buck a kilo and make MONEY at it.

An old nuke plant operates at a cost of 1.8 cents a kwh and todays 75-85% eff room temp systems can convert that into under a buck h2 per kilo.. advanced type 3 reactors on the market now can drive that cost down I think it was to 1.4 cents per kwh and thus maybe 75 cent h2...

The grand poobah of nuke h2 cheapness.. the type 4 reactor...might reach 24 cents per kilo.

And then long long before uranium and plutonium and thorium.. comes fusion and that is CHEAP h2 ib BULK.

Finaly the h2 storage tanks dont weight much.. 41 kilos each. And as fuel cells are getting far better fast they wont need 5 kilos of h2 unless its a freaking hummer or 4 ton limo. Honda already jas proven that in REAL WORLD on the road cars...

OK, nukes type 3-4 are great H2 byproduct resources. But we have yet to provide any reliable method of nuke waste treatment - or is it simply not yet "available?"

This talk of reaching efficiences greater than 100% is basically not possible.

The only thing that I can think of that may make it look like it's over 100% is the fact that at 100 deg C, it takes 350 MJ to produce 1 kg of hydrogen (41% efficient). At 850C, it takes 225 MJ to produce 1 kg of hydrogen (64% efficient). These are electricity to hydrogen figures.

Also some of the efficiency numbers include the energy stored in the oxygen as well as the hydrogen. These are the very weird efficiency numbers in the 80%+ region, I expect.

When combined with Carnot losses from a typical power plant the numbers drop even more. When talking efficiency, it is important to say from what perspective. From the heat generated from the actual plant or is it just from the electricity from the plant.

Taken this into consideration, from the perspective of the heat generated in the power plant to the hydrogen, conventional electrolysis is only 30% (due to plant/conversion losses). High temperature electrolysis is around 45-50% efficient, since the heat is used directly to partially produce the hydrogen and not electricity then to hydrogen. Direct heat processes like the Sulfer-Iodine cycle are around 50%.

At around 2500 C, thermolysis occurs and water breaks down into hydrogen and oxygen, which is probably the most efficient way without catalysts but is the most difficult to achieve.


http://www.chemie.de/lexikon/e/High-temperature_electrolysis

http://www.chemie.de/lexikon/e/Hydrogen_production

http://en.wikipedia.org/wiki/Electrolysis

http://www.greencarcongress.com/2004/11/milestone_for_h.html

Addendum,

I would like to add that the 1.8 cents (from the NEI) cost of production for nuclear energy doesn't include capital costs.

This is not the levelized cost of the energy (which includes capital and maintenance), which represents the costs that the consumer will eventually have to pay.

According to MIT's Future of Nuclear Power (2003), a new generation power reactor would have a levelized energy cost of around 6-7 c/KWh. Busnessweek put it in even starker terms. Maybe with manufacturing changes and upgrades, the costs will come down but realistically we are stuck with the reality of the costs that are well documented from Japan's ABWRs to the EPR in Olkiluoto, Finland.

Also would like to point out that the closest thing we have to a Gen IV design is the South African PBMR. The prototype is supposed to start next year. The earliest it could start commercial production would be in 2016. The NGNP (Next Generation Nuclear Plant), is supposedly to be built by 2021, and it doesn't even have a stable final design. The other Gen IV designs are not expected to be done by 2030 for commercial construction.

Sorry to rain on anybody's parade but I read way too much ...

http://www.world-nuclear-news.org/newNuclear/Next_Generation_Nuclear_Plant_revived_240707.shtml

http://www.businessweek.com/magazine/content/06_28/b3992063.htm

http://web.mit.edu/nuclearpower/

Heh thats why the power compampanies forced the gov to pay for all cost overruns and provide the plants entire cost as an interest free loan. No more need to worry about the stupidly inefficent regulatory process and all those little obstruction lawsuits.
And even on the old plants they forced huge deals to make the entire cost back.

As for waste thats intenssional. The us doesnt want waste processing and all because without it the us nuke industry has effectively stored away enough nuke fuel in the form of "waste" to power enough reactors to power everything we needs for centuries.

Every year a plant operates 2-3 DECADES worth of fuel is stored becayse the system only uses 3-5% of the fuel before its decared waste.

In fact we realy want all the nuke waste we can get.

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