Engineering Carbon for Impressive Hydrogen Storage

May 22, 2009 by Laura Mgrdichian feature

(PhysOrg.com) -- University of Missouri researchers recently showed how carbon nanostructures can be engineered to become excellent media for hydrogen storage, work that may be important for the advancement of hydrogen-energy technologies for vehicles and other applications, which have been slow to develop due to the lack of suitable storage materials.

Using a combination of experiement and computer modeling, the group investigated the storage potential of various “nanoporous” carbon materials - carbon that contains tiny vacant spaces with diameters ranging from less than one nanometer to several .

Nanoporous carbon is a member of a class of materials being targeted as promising storage candidates because they can reversibly store hydrogen, are easy to load with hydrogen, and don't have heat-management issues. Carbon has an edge over other materials because it is both cheap and lightweight, but the low interaction energies between hydrogen molecules and lead to storage capacities that are inadequate at room temperature.

But no material, carbon or otherwise, presently comes close to the 2010 targets that the U.S. Department of Energy (DOE) has set for at low-pressure, room-temperature conditions, namely 45 grams (g) of hydrogen per kilogram (H2/kg) material for rigid storage materials and 28 g per liter for liquid storage.

“Our work makes the case that it is possible to significantly increase hydrogen storage capacities in carbon materials by engineering the nanopores,” said University of Missouri physicist Carlos Wexler, the study's corresponding researcher, to PhysOrg.com.

Wexler and his group learned that the tendency for hydrogen and carbon to bind can be made much more likely by tailoring the material to certain specifications such that the binding energy between the two materials is raised, meaning they bond more strongly. They published their findings in the journal Nanotechnology.

Their approach has two key parts. First, it is necessary to engineer the material such that the ratio of its surface area to its volume is very high. This creates lots of surfaces, with lots of nanopores, maximizing adsorption while still using a small amount of material. Here, the researchers created tiny carbon granules (using a method, interestingly, that involves heating ground corncob, an agricultural waste product), which boast approximately 3100 square meters of surface area in a single gram. Further, the tiny width of the pores creates deep potential-energy wells that almost double the binding energy.

Second, they conclude that “doping” the carbon with a small amount of an element can boost the hydrogen-carbon interaction; examples of suitable elements include boron, iron, and nitrogen.

Because nanoporous carbon is a solid storage material, the DOE goal of 45 g H2/kg applies. The group's experimental results yielded storage capacities of up to 100 g H2/kg at 83 degrees Kelvin (about -310 degrees Fahrenheit) and 20 g H2/kg at a much more reasonable 303 K (about 86 °F).

“We think this shows that, with some work, it may be possible to meet those DOE goals by 2010,” said Wexler.

More information: Nanotechnology 20 (2009) 204026, all-craft.missouri.edu/

Copyright 2009 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

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User comments : 14

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Birger
4 / 5 (1) May 22, 2009
Impressive, but hold your cigars until a material actually is proven to meet the DOE requirements, and production in bulk has been demonstrated. My point is, don't commit the new transport infrastructure to any single solution until several promising technologies have been tested in parallel. There is a plethora of new technical solutions for transportation "in the pipeline".
El_Nose
2 / 5 (1) May 22, 2009
it only makes sense to let the market decide the future of energy. The government can do what ever it likes but like VHS vs Beta and Blu-ray vs HD DVD the market will decide the best and cheapest technology that will have the greatest profit and penetration potential. Personally i like fuel cells but i like super capacitance batteries even more - fuel cells are fimiliar you can refill your car -- but batteries with very low charge times (MINUTES) would be ideal. And to support this new enegry need i say more wind -- not economical but people are willing to build -- more nuclear more hazzerdous waste but we are getting better at that --- more money into fusion like the ITER project --- and energy transimmission technology such as the proposal to beam energy back to earth from giant satellite solar farms. We have the technology but the money and vision to push anything forward is lacking because the market has yet to figure out who the winner will be -- Hydrogen or batteries --- Who are you voting for??
3432682
3 / 5 (2) May 22, 2009
20 grams storage per 1000 grams of tank weight at 86 F. That's 2%, insufficient. How about if it's pressurized? Any other tricks to boost efficiency?

It's clear that alternative energy is a nice slogan, far from practicality. Liberals are going to destroy the economy with mandates for implementation far before the technology is economical, like the insane goal of 80% replacement by 2050, and 20% by 2020. Alas, they're spending far more on global warming research than on developing alternative energy products. Paving the road to hell with good intentions, as always.
NeilFarbstein
1 / 5 (1) May 22, 2009
Battery power full steam ahead!
E_L_Earnhardt
1 / 5 (1) May 23, 2009
The same technology that makes for hydrogen storage
would make a great BATTERY! "Conductivity" is the fly in the ointment! Now if you could marry some "nanometal" into that carbon -
ormondotvos
not rated yet May 23, 2009
Since there is a strong early adopter market, why not start now with some standardized storage space in the vehicle, and give consumers the choice of range? As better, and doubtless more expensive solutions come along, the previous storage space can be reused, maybe with a resale market for low range storage modules. Taxibus comes to mind.



http://www.taxibus.org.uk
Soylent
5 / 5 (1) May 24, 2009
It's clear that alternative energy is a nice slogan, far from practicality.


Hydrogen is energy storage not energy generation.

Liberals are going to destroy the economy with mandates for implementation far before the technology is economical, like the insane goal of 80% replacement by 2050, and 20% by 2020.


Hydrogen is not electricity. It is steam reformed from fossil fuels.

That goal is trivial. You were well on your way to replacing coal and baseload natural gas with nuclear(it would not exist today if you had continued at the same rate) until 20% interest rates and NRC killed it(when it takes 5 years to get through the regulatory process and fossil fuel interests posing as and funding anti-nuclear "environmentalists" are given ample opportunities to delay progress for many years through legal challenges you're screwed; costs go through the roof).

Alas, they're spending far more on global warming research than on developing alternative energy products.


That's demonstrably false. A huge amount of cash has been sunk into the rat hole of wind and solar energy(or rather the pocket of some rat...) and a tiny amount of near useless intermittent electricity is all there is to show for it.
NeilFarbstein
1 / 5 (1) May 24, 2009
The utilities in southern California and the southwest are adding CSP solar thermal at an incredible rate; between 2009 and 2012 the industry will grow 14 times. Solar thermal is the cheapest type of solar electricity- it supplies the same amount of energy as a barrel of sold at a price of $50 per barrel. People in the industry expect it to get down to about $20 per barrel.
Soylent
5 / 5 (2) May 25, 2009
The utilities in southern California and the southwest are adding CSP solar thermal at an incredible rate; between 2009 and 2012 the industry will grow 14 times.


14 times nothing is still nothing.

Solar thermal is the cheapest type of solar electricity...


That's not saying much.

it supplies the same amount of energy as a barrel of sold at a price of $50 per barrel.


You either don't understand that statistic or you are being intentionally misleading.

These plants generate a barrel of oil equivalent of _heat_ at $50 per barrel(with our without the outrageous subsidies they are recieving?).

You might notice that at $50 per barrel almost no one is burning oil in power plants for generating electricity because it's outrageously expensive.

The solar thermal plant also needs to convert that heat to electricity and transmit that electricity from the middle of a desert where no one lives to the nearest city(transmission usually payed for by tax payers) and that's where much of the cost of the plant lies. It's also not a terribly clever idea to use a lot of fresh-water for cooling in the midle of a desert; if you use air cooling you take a hit to your efficiency and add yet more capital cost. If you add molten salt storage and try to do baseload you'll pay even more.

Looking at an actual system like Ausra's, and not just their marketing material, it cost $3000 per kW of installed capacity in overnight costs(i.e. ignoring interest if funds were borrowed). With an outrageously poor capacity factor of 18-22% the overnight cost is on the order of $15 000/kW baseload equivalent. If you build a GW scale plant you're going to pay on the order of $20 000-30 000 per kW baseload equivalent when you include interest.

Now, of course, you're not going to use it for baseload since this is insanely expensive. You're going to try to use it for peak-load, try to bilk the tax payer(feed in tarriffs, renewable portfolio standard, transmission provided by taxpayer etc.), sell carbon credits and so on, because that's the only way the economics work out.

If you weren't trying to bilk the tax payer, you'd have to shift the peak output by several hours(since peak output occurs at noon and the peak usage occurs later in the day) and you'd do that with molten salt storage. You'd also have to install the plants in sub-optimal locations where fresh water is cheaper and access to the grid is nearer(since you now are paying for it).

Solar thermal is very mature technology. A lot of very clever people have been trying to make it work economically for over a century and very little improvement has actually happened.



It's sobering to look at old photographs from Frank Schuman's large, parabolic through array and realize that these people were doing and thinking the exact same damn things solar proponents are today:

"Sun power is now a fact and no longer in the 'beautiful possibility' stage... It will have a history like aerial navigation. Up to twelve years ago it was a mere possibility and no one took it seriously." - Frank Schuman
brentrobot
not rated yet May 27, 2009
I concur soylent, nuclear is the way to go. Everything else is a "crack" pipe dream. Few policy makers have even a basic grasp of market forces let alone simple mathematics.
goldengod
1 / 5 (1) May 27, 2009
Nuclear is not the only way and has so much associated risk that other more expensive options are definitely worth pursuing.

It no surprise that the economics are warped in any sector of the energy industry. Where ever you look it's the same few players making the big investments and they all have the same methods for maintaining their grip on the control levers.
Velanarris
not rated yet May 29, 2009
Nuclear is not the only way and has so much associated risk that other more expensive options are definitely worth pursuing.
What to let us know what those risks are? It's not fissionable weapons material as breeders don't create fissionable material. It's not waste as breeder reactors are self fueling and do not break down their materials into "nuclear sludge". Wanna talk about Chernoble or 3 mile island? Both accidents were due to faulty design, designs which are STILL RUNNING OUR ENTIRE NUCLEAR GRID. Wouldn't you like to upgrade them? What other concerns are there?

It no surprise that the economics are warped in any sector of the energy industry. Where ever you look it's the same few players making the big investments and they all have the same methods for maintaining their grip on the control levers.


Yes, exploit false data about environmental alarm so that I can take control of the energy grid with X technology, that won't work, so instead I can sell my coal/oil/gas reserves as a replacement under contract.

Enron started the green energy kick in the late 80's. Funny thing is when they said, "No one knows the extent of horrors we'll uncover in regards to Enron's machinations." they were unequivocally correct.

Looks like we're finding out now.
NeilFarbstein
1 / 5 (1) May 31, 2009
The utilities in southern California and the southwest are adding CSP solar thermal at an incredible rate; between 2009 and 2012 the industry will grow 14 times.




14 times nothing is still nothing.



Solar thermal is the cheapest type of solar electricity...




That's not saying much.



it supplies the same amount of energy as a barrel of sold at a price of $50 per barrel.




You either don't understand that statistic or you are being intentionally misleading.



These plants generate a barrel of oil equivalent of _heat_ at $50 per barrel(with our without the outrageous subsidies they are recieving?).



You might notice that at $50 per barrel almost no one is burning oil in power plants for generating electricity because it's outrageously expensive.



The solar thermal plant also needs to convert that heat to electricity and transmit that electricity from the middle of a desert where no one lives to the nearest city(transmission usually payed for by tax payers) and that's where much of the cost of the plant lies. It's also not a terribly clever idea to use a lot of fresh-water for cooling in the midle of a desert; if you use air cooling you take a hit to your efficiency and add yet more capital cost. If you add molten salt storage and try to do baseload you'll pay even more.



Looking at an actual system like Ausra's, and not just their marketing material, it cost $3000 per kW of installed capacity in overnight costs(i.e. ignoring interest if funds were borrowed). With an outrageously poor capacity factor of 18-22% the overnight cost is on the order of $15 000/kW baseload equivalent. If you build a GW scale plant you're going to pay on the order of $20 000-30 000 per kW baseload equivalent when you include interest.



Now, of course, you're not going to use it for baseload since this is insanely expensive. You're going to try to use it for peak-load, try to bilk the tax payer(feed in tarriffs, renewable portfolio standard, transmission provided by taxpayer etc.), sell carbon credits and so on, because that's the only way the economics work out.



If you weren't trying to bilk the tax payer, you'd have to shift the peak output by several hours(since peak output occurs at noon and the peak usage occurs later in the day) and you'd do that with molten salt storage. You'd also have to install the plants in sub-optimal locations where fresh water is cheaper and access to the grid is nearer(since you now are paying for it).



Solar thermal is very mature technology. A lot of very clever people have been trying to make it work economically for over a century and very little improvement has actually happened.







It's sobering to look at old photographs from Frank Schuman's large, parabolic through array and realize that these people were doing and thinking the exact same damn things solar proponents are today:



"Sun power is now a fact and no longer in the 'beautiful possibility' stage... It will have a history like aerial navigation. Up to twelve years ago it was a mere possibility and no one took it seriously." - Frank Schuman


Where did you get those figures?

Brightsouce will be generating 1300 gigawatts of solar thermal energy in the southwest very soon.
There's another big problem with nuclear, the sky high insurance bills in case they release radioactivity in accidents. The cost of solar thermal is going down. It's fact. Solar energy breakthroughs are going to make solar enrgy as cheap and plentiful as fossil fuels and nuclear. Nuclear is too dangerous, we should develop renewable energy.
Velanarris
not rated yet Jun 01, 2009
Nuclear is too dangerous, we should develop renewable energy.
Old nuclear designs are dangerous and prone to leak. So instead of replacing them with cleaner, safer nuclear designs you'd rather leave the Uranium and Plutonium based reactors in place?

And can you name the last nuclear leak that contaminated anything?

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