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The team used xylose -- a simple plant sugar

Virginia Tech researchers have found a way to produce large amounts of hydrogen inexpensively using a simple plant sugar.

Y.H. Percival Zhang, study leader and an associate professor of biological systems engineering at Virginia Tech, and his team have produced large quantities of hydrogen in an effort to lessen the dependence of fossil fuels.

Zhang and his team used xylose in the study, which is a sugar first isolated from wood. Not only is this form of hydrogen production inexpensive and environmentally friendly, but it can also occur using any source of biomass. 

Up until now, producing hydrogen gas from biomass was a costly process that didn't yield very much in the end.


For this study, Zhang and his team liberated the hydrogen under normal atmospheric pressure and mild reaction conditions at 122 degrees. A group of enzymes -- which were isolated from various microorganisms at extreme temperatures -- were used as biocatalysts to release the hydrogen.

The team used xylose to release the hydrogen, which hasn't been used much in the past because most scientists use natural or engineered microorganisms. These cannot create large quantities of hydrogen because the microorganisms grow and reproduce instead of splitting water molecules for the creation of pure hydrogen.

The energy stored in Xylose splits water molecules, thus creating very pure hydrogen that can be used by proton-exchange membrane fuel cells.

The team separated some of the enzymes from their native microorganisms to create a special enzyme mixture.  When the enzymes were combined with xylose and a polyphosphate, a large amount of hydrogen was liberated from the xylose.

In fact, the team produced about three times as much hydrogen as other hydrogen-producing microorganisms.

“Our new process could help end our dependence on fossil fuels,” said Zhang. "Hydrogen is one of the most important biofuels of the future.”

Source: Virginia Tech News



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RE: One problem...
By Solandri on 4/7/2013 3:53:06 PM , Rating: 2
quote:
Internal combustion engines are at best 30% efficient while a fuel cell is generally 40-60% efficient.

When we're talking about pumping fuel out of the ground, then engine/cell efficiency is all that matters (assuming they use the same fuel).

When we're talking about manufacturing fuel from another source (e.g. plant matter), then you need to take into account the efficiency of that process as well.

Currently, manufacturing hydrogen is about 25% efficient. 40% efficiency to generate the electricity needed for electrolysis, 60-65% efficiency for the electrolysis process itself. Multiply that by the ~50% efficiency of a fuel cell and the overall efficiency for hydrogen is a pathetic 12.5%. That's why hydrogen cars haven't made any progress - overall efficiency is still much lower than ICE cars.

In the context of this article, the efficiency you need to compare is not just engine efficiency, but also production efficiency. What's the efficiency of converting plant matter to ethanol? Multiply that by the efficiency of an ethanol-powered engine. What's the efficiency of this new process to convert plant matter to hydrogen? Multiply that by the efficiency of a hydrogen fuel cell. Then compare the two. Just because fuel cells are more efficient doesn't automatically make them better. If the production efficiency of manufacturing hydrogen is less efficient than manufacturing ethanol, then ethanol can still be the more efficient solution overall despite the engine being less efficient.

(Arguments about storage, safety, cost, etc. while relevant are independent of efficiency so can be considered separately. That said, nearly all of these other factors favor ethanol-powered engines over both EVs and hydrogen fuel cells. So it's even possible for ethanol-powered ICEs to have a lower overall efficiency, yet a better solution overall.)

quote:
Also, why do people only think of cars when talking about fuel cells? They are a way to produce energy, it isn't only useful in vehicles. I know that some data centers are using them as a backup power source and even to offset their external energy use.

About 40% of U.S. energy consumption is for transportation (mobile applications where you're disconnected from the electrical or natural gas grid). So that's where changes in power source are going to make the biggest impact.

While the use of fuel cells in data centers is interesting, it's a negligible part of overall energy consumption. In fact, in general, energy consumption for static applications is not a problem worthy of consideration. Electrical transmission is over 95% efficient, so any advances in production can be adopted at the power plant instead of at the point of consumption (like a data center). About the only static application where electricity would be non-optimal is heating. But that's because heaters are by definition 100% efficient, so there's literally no room for improvement over a wood/gas/oil furnace.

So it's really only mobile/transportation applications where there's potentially a lot to be gained from advances in energy storage.


RE: One problem...
By kyuuketsuki on 4/7/2013 7:11:47 PM , Rating: 3
Where are you getting all those numbers for the efficiency of various stages of hydrogen production? Seems to me like you're just pulling those out of thin air. Plus, even if they are accurate, you're obviously not taking into account the efficiency of the new process described in the article, since it's not a current manufacturing process.

Plus, what are the numbers for the various stages of extracting/transporting/burning gasoline and ethanol? You claim that both are more efficient than hydrogen, yet don't provide any proof.

Really, if hydrogen can be produced efficiently, then the only issue left is storage, which is an engineering problem that would be solved fairly quickly, I think, once hydrogen is feasible as a fuel in the first place. We've had tanks full of explosive fuel in our vehicles forever, and we already have vehicles running on a pressurized flammable gas (CNG).


RE: One problem...
By Solandri on 4/7/2013 9:49:33 PM , Rating: 1
quote:
Where are you getting all those numbers for the efficiency of various stages of hydrogen production? Seems to me like you're just pulling those out of thin air.

I'm getting them from years of mulling over and learning about these different technologies. 40% is about the efficiency of a modern coal plant. Coal produces most of our electricity.

60-65% is the efficiency of electrolysis of water. You can get higher - up to 80%-95%, but that usually comes at the cost of (much) slower conversion rates. Unfeasible for wide-scale production of hydrogen.
http://en.wikipedia.org/wiki/Electrolysis_of_water...

quote:
Plus, even if they are accurate, you're obviously not taking into account the efficiency of the new process described in the article, since it's not a current manufacturing process.

Well that was my point. You can't just point to this new hydrogen production method and say "Look! Hydrogen is free now!" You have to compare it against an alternative use of that plant matter - conversion into ethanol. You always have to compare against opportunity costs, not against a vacuum.

quote:
Plus, what are the numbers for the various stages of extracting/transporting/burning gasoline and ethanol? You claim that both are more efficient than hydrogen, yet don't provide any proof.

Isn't it obvious? Gasoline and ethanol can be stored and transported as a liquid at room temperature and normal atmospheric pressure. Hydrogen either needs to be compressed or chilled. And due to H2 being a tiny molecule, hoses and fittings which can carry gasoline and alcohol without leaking cannot carry hydrogen without leaking. So the storage and transportation cost of hydrogen will always be higher than for gasoline and ethanol.

quote:
Really, if hydrogen can be produced efficiently, then the only issue left is storage, which is an engineering problem that would be solved fairly quickly

If you know anyone who works in a lab which uses H2 gas (or He gas, which is an even smaller molecule), please have a chat with them. The stuff leaks out of even well-designed storage tanks and hoses/fittings.

The entire reason petroleum and alcohols are preferred as fuels is because they bind hydrogen into a molecule which is much easier and safer to store and handle, while only giving up a little of the energy. The difficulty with storing and transporting hydrogen gas is driving some hydrogen fuel cell researchers to try out methane and methanol as fuels instead of pure hydrogen gas. Well, if you keep going down that path, you arrive right back at where we started - petroleum and alcohol as the optimal way to store and transport energy in hydrogen atoms.


RE: One problem...
By Alexvrb on 4/7/2013 10:55:02 PM , Rating: 2
Up until now, producing hydrogen gas from biomass was a costly process that didn't yield very much in the end. But now... with this latest breakthrough... producing hydrogen gas from biomass is a costly process that yields a bit more.


RE: One problem...
By Kyuu on 4/8/2013 1:03:46 AM , Rating: 2
Okay... fair enough. Thanks for the info.

It looks like there are at least a couple of promising technologies under development for mobile hydrogen storage, though, like cryo-compression and metal organic frameworks.


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