Research demonstrates method that allows inexpensive carbon materials to store hydrogen at room temperature

Sep 19, 2011 by David Chandler

Hydrogen has long been considered a promising alternative to fossil fuels for powering cars, trucks and even homes. But one major obstacle has been finding lightweight, robust and inexpensive ways of storing the gas, whose atoms are so tiny they can easily escape from many kinds of containers.

New research by a team from MIT and several other institutions analyzes the performance of a class of materials considered a promising candidate for such storage: activated carbon that incorporates a , so can bond directly to the surface of and then be released when needed.

Such a could avoid the cost and weight associated with conventional : Current approaches either liquefy the gas, requiring energy-intensive systems and heavy to maintain a temperature of minus 423 degrees Fahrenheit; or store it under high pressure, requiring powerful pumps and robust tanks to withstand 5,000 to 10,000 pounds per square inch (psi) of pressure. Bonding the to a highly porous, sponge-like material such as a or activated carbon makes it possible to use ambient pressure and in storage tanks that could be lighter, cheaper and safer.

The tricky part of designing such systems is finding a storage medium that bonds the hydrogen atoms tightly enough so they don’t leak away, but not so tightly that they can’t be released when needed. “You have to be able to pump the gas in [at room temperature], and release it when you need it to burn,” explains MIT's Sow-Hsin Chen, senior author of a paper describing the new method.

Such a storage system could be key to making hydrogen-powered cars practical and economically viable, and has been a key goal of the U.S. Department of Energy (DoE). The hydrogen fuel could be made by splitting water; fuel cells would then “burn” the fuel with no emissions at all except water vapor.

Activated carbon has been proposed as a possible storage medium that could work by bonding dissociated hydrogen atoms, but previously there was no good way of analyzing the material’s behavior and optimizing its storage capability. Now, such a method has been demonstrated by a team led by Chen, MIT professor emeritus in the Department of Nuclear Science and Engineering; former student Yun Liu SM ’03, PhD ’05, now at the National Institute of Standards and Technology and the University of Delaware; and researchers at Taiwan’s Institute of Nuclear Energy Research (including lead author Cheng-Si Tsao, who was a visiting scientist at MIT for a year working with Chen), National Tsinghua University in Taiwan and Pennsylvania State University. Their findings were reported in a paper published online in the Journal of Physical Chemistry Letters in August, and scheduled to appear in a forthcoming print issue.

The team analyzed the activated carbon’s storage of hydrogen using a technique called inelastic neutron scattering, which they say is uniquely capable of determining whether the hydrogen in the sample exists as individual atoms or H2 molecules. This approach can also assess the gas’s interaction with the storage material.

Using this method, they were able to provide convincing evidence, for the first time, that hydrogen moves into the material as a result of a phenomenon called the spillover effect, in which atoms — thanks to the presence of platinum particles as a catalyst — split off from their molecules and diffuse through the carbon, where they bond to its surface. Other researchers had suspected the spillover effect was involved, but had been unable to demonstrate that this was the case. “Although this concept had been proposed, there was a lot of debate about it in the community,” Liu says.

The new analysis method should make it possible to fine-tune the properties of the activated carbon material to increase its storage capacity, Chen says. The key is to find the optimum sizes and concentrations for the particles of platinum and carbon, he adds. Ultimately, the researchers also hope to identify a catalyst more abundant and less expensive than platinum.

This storage system, once tuned to achieve the desired capacity, should be capable of storing hydrogen under moderate pressure (possibly around 500 psi), then releasing the gas on demand simply by releasing the pressure, Chen says. “When you break the hydrogen molecules down to atoms” using the spillover effect, “it binds with the material with much less binding energy, so you can pump it out easily,” he says.

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User comments : 16

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CHollman82
1 / 5 (7) Sep 19, 2011
I don't understand how you can take water, use the hydrogen as a fuel, and get only water vapor emissions... Seems like you would get primarily oxygen emissions if the system is efficient, and if that's the case then 100 years from now when billions of vehicles use this technology we would be raising the oxygen content of the atmosphere relative to the hydrogen content... which obviously wouldn't be good.
darthbonobo
4.5 / 5 (2) Sep 19, 2011
When you burn hydrogen, it combines with oxygen to form water. Sooo, the O2 wouldn't be building up...
that_guy
3 / 5 (1) Sep 19, 2011
I don't understand how you can take water, use the hydrogen as a fuel, and get only water vapor emissions... Seems like you would get primarily oxygen emissions if the system is efficient, and if that's the case then 100 years from now when billions of vehicles use this technology we would be raising the oxygen content of the atmosphere relative to the hydrogen content... which obviously wouldn't be good.

chollman82....
Are you proposing that we take the water, electrolyze it, and then use the Hydrogen as a fuel? Really? You do realize that it takes more energy to get the hydrogen from the water, than the actual energy you get from hydrogen, right? Are you getting what I'm saying here? Hydrogen is an energy storage medium. If we could so easily get so much energy from water, don't you think we would have power plants that run on hydrogen taken from water?

judging from your screen name, you should know better than to make that statement. I'm basically calling you stupid.
paulo
1.8 / 5 (6) Sep 19, 2011
what's cheap about platinum?
that_guy
5 / 5 (3) Sep 19, 2011
what's cheap about platinum?

Ultimately, the researchers also hope to identify a catalyst more abundant and less expensive than platinum.

I'd like to point out that they are trying to use inexpensive CARBON materials. Platinum, being the catalyst, is not the 'cheap' material that they are referring to. It does not store the hydrogen, it helps the carbon material bond with and store the hydrogen.
SR71BlackBird
5 / 5 (3) Sep 20, 2011
This is extremely good news! I suspect that the energy-to-weight ratio for hydrogen will far exceed that of current battery technology in the coming years. This is still just an energy storage medium leaving us with our initial problem of finding more efficient energy conversion methods. I suspect solar, wind and nuclear could sustain our energy demands. One step closer to getting rid of fossil fuels!
Temple
3 / 5 (2) Sep 20, 2011
Are you proposing that we take the water, electrolyze it, and then use the Hydrogen as a fuel? Really? You do realize that it takes more energy to get the hydrogen from the water, than the actual energy you get from hydrogen, right? Are you getting what I'm saying here? Hydrogen is an energy storage medium. If we could so easily get so much energy from water, don't you think we would have power plants that run on hydrogen taken from water?

judging from your screen name, you should know better than to make that statement. I'm basically calling you stupid.


Before you so quickly call people stupid, you should at least try to make sure what you are saying is not entirely foolish.

You do realize that *every* form of energy transformation, transportation, or storage is inherently inefficient don't you?

Going from oil in the ground to a liter of gasoline requires using up a frightening amount of energy as well.

Hydrogen isn't intended as an energy source (aside from fusion).
unknownorgin
1 / 5 (1) Sep 20, 2011
I could be wrong but when single hydrogen atoms recombine to form the H2 molecule some heat is generated {exothermic reaction) so even with a catalyst if the H2 molecule is split it would require some form of energy input to do so.
sex_doctor
not rated yet Sep 20, 2011
finitesolutions
not rated yet Sep 20, 2011
Incet incet o solutie pentru camioane cu hidrogen se creeaza. Masinile electrice s-ar putea sa moara a doua oara de data asta din cauza masinilor cu hidrogen.
Eikka
3.5 / 5 (4) Sep 20, 2011
A cheap method of storing hydrogen with carbon already exists: methane, ethane, propane, butane, pentane, hexane, heptane, octane...

CHollman82
2.3 / 5 (3) Sep 20, 2011
Are you proposing that we take the water, electrolyze it, and then use the Hydrogen as a fuel? Really? You do realize that it takes more energy to get the hydrogen from the water, than the actual energy you get from hydrogen, right? Are you getting what I'm saying here? Hydrogen is an energy storage medium. If we could so easily get so much energy from water, don't you think we would have power plants that run on hydrogen taken from water?

judging from your screen name, you should know better than to make that statement. I'm basically calling you stupid.


Clearly I misunderstood the article, the context (with certain assumptions) in which my comment was framed. Thank you for acting so maturely in explaining my error.
Ricochet
3.7 / 5 (3) Sep 20, 2011
A cheap method of storing hydrogen with carbon already exists: methane, ethane, propane, butane, pentane, hexane, heptane, octane...


Fossil fuel, fossil fuel, fossil fuel, fossil fuel, fossil fuel, fossil fuel, fossil fuel, fossil fuel...
that_guy
3 / 5 (1) Sep 20, 2011
Before you so quickly call people stupid, you should at least try to make sure what you are saying is not entirely foolish.

You do realize that *every* form of energy transformation, transportation, or storage is inherently inefficient don't you?...Hydrogen isn't intended as an energy source (aside from fusion.)

While your comment makes sense by itself, in context of what I said, it makes absolutely no sense. If you will call me out on the facts, at least understand the facts I stated.

What I said regarding CHallman was basically that the way he has proposing entailed bringing the energy to electrolize the water, and then use the Hydrogent as fuel. If you had that energy with you in another form in the first place, you would have no reason to add an extra conversion and lose energy in the process. So, temple...

@Chollman - You're right, I was mean with that comment. I apologize.
Temple
not rated yet Sep 20, 2011
@that_guy

No, I don't think you read his (albeit misguided) post well enough, rather you were too quick to jump down his throat and read a lot into it. He didn't talk about gaining energy through the electrolysis of water, you introduced that concept and then eviscerated him for it.

And the 'hydrogen economy' (for what it's worth, for what it may ever be worth) is very similar to all energy storage/transport solutions. Available energy is used to transform a medium into an energy consumable or to store it. That's inherently lossy.

Would that we could use energy we have on hand instead of converting it lossly into a fuel that can be used more flexibly. We would be quite a bit further along on the road of efficiency.
Ricochet
not rated yet Sep 20, 2011
Found this interesting article. It's from a .gov site, so it HAS to be true...right? yeah... anyway, here it is...
http://www.newton...9469.htm
So that about cuts it for water as fuel... takes more energy to separate it (using conventional electrolysis) and yields less energy than it takes to produce it. Then there's apparently a problem with water vapor being the "best" greenhouse gas so could cause problems on a wide scale. So, looks like we're left with all these exotic plans for obtaining and storing hydrogren.

I think we should dump all our current expirements and plans, and go for pocket singularities.

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