Skip to comments.Researchers Develop Method for Enzymatic Production of Hydrogen from Biomass at High Yields
Posted on 05/23/2007 11:46:25 AM PDT by Red Badger
Researchers at Virginia Tech, Oak Ridge National Laboratory (ORNL), and the University of Georgia have developed a novel method using multiple enzymes as a catalyst for the direct, low-cost production of hydrogen from biomass.
Applying the principles of synthetic biology, the researchers use a combination of 13 enzymes to form an unnatural enzymatic pathway to completely convert polysaccharidese.g., starch and celluloseand water into hydrogen at a yield higher than the theoretical yield of biological hydrogen fermentations. Their work is described in the 23 May issue of PLoS ONE, the online, open-access journal from the Public Library of Science.
he synthetic metabolic pathway for conversion of polysaccharides and water to hydrogen and carbon dioxide.
Hydrogen production from either 2 mM G-6-P or 2 mM starch (glucose equivalent) using the new method.
Starch is a high energy-density carrier, with 14.8 H2-based mass%. (The DOE long-term target for hydrogen storage is 12 mass%.) The enzymes, when added to the biomass solution, use the energy in the polysaccharides to break the water up into carbon dioxide and hydrogen.
A membrane bleeds off the carbon dioxide and the hydrogen is used by a fuel cell to create electricity. The water byproduct is recycled for the starch-water reactor. Laboratory tests confirm that it all takes place at low temperature30° Cand atmospheric pressure. The researchers estimated the cost of hydrogen production using their method of approximately $2/kg.
The stoichiometric reaction is:
C6H10O5 (l) + 7 H2O (l) → 12 H2 (g)+6 CO2 (g)
The overall process is spontaneous and unidirectional because of a negative Gibbs free energy and separation of the gaseous products with the aqueous reactants.
The vision is for the ingredients to be mixed in the fuel tank of a car. A car with an approximately 12-gallon tank could hold 27 kg of starch, which is the equivalent of 4 kg of hydrogen. One kg of starch will produce the same energy output as 1.12 kg (0.38 gallons) of gasoline.
The research was based on earlier work by Y.H. Percival Zhang, assistant professor of biological systems engineering at Virginia Tech pertaining to cellulosic ethanol production (earlier post) and the ORNL and University of Georgia researchers' work with enzymatic hydrogen production.
One of the team, Michael W.W. Adams of the University of Georgia UGA, is co-author of the first enzymatic hydrogen paper in Nature Biotechnology in 1996. The researchers were certain they could combine the processes.
In nature, most hydrogen is produced from anaerobic fermentation. But hydrogen, along with acetic acid, is a co-product and the hydrogen yield is pretty lowonly four molecules per molecule of glucose. In our process, hydrogen is the main product and hydrogen yields are three-times higher, and the likely production costs are lowabout $1 per pound of hydrogen.
What is more important, the energy conversion efficiency from the sugar-hydrogen-fuel cell system is extremely highgreater than three times higher than a sugar-ethanol-internal combustion engine. It means that if about 30 percent of transportation fuel can be replaced by ethanol from biomass as the DOE proposed, the same amount of biomass will be sufficient to provide 100 percent of vehicle transportation fuel through this technology. Y.H. Percival Zhang
The next step for the team is to increase reaction rates and reduce enzyme costs.
High-Yield Hydrogen Production from Starch and Water by a Synthetic Enzymatic Pathway; Y.H. Percival Zhang, Barbara R. Evans, Jonathan R. Mielenz, Robert C. Hopkins, Michael W.W. Adams; PLoS ONE 2(5): e456. doi:10.1371/journal.pone.0000456
Rest In Peace, old friend, your work is finished.......
If you want on or off the DIESEL "KnOcK" LIST just FReepmail me........
This is a fairly HIGH VOLUME ping list on some days......
MAYBE THEY CAN TWEAK IT TO MAKE BIODIESEL?.......
Hydrogen from Biomass PING!.......
So, we’ll be really skinny people driving hydrogen powered SUV’S!..............
We don’t eat every source of biomass.
Yeah. Screw the people who starve. They deserve it.
But if you look at the redox reaction, it yields 6 parts CO2 - oh no!
The enviro-wankers will be all up in arms!
Maybe they could even create a proton gradient across a membrane that would power fast-rotating proteins that produce energetic molecules to be used in cellular respiration.
Every source of biomass is grown on land and by methods that are used to grow food.
Devote more of that land to fuel production, and less of it is devoted to food production.
Please Freep Mail me if you'd like on/off
Do you know how much land could be growing something like switch grass without any change in tilled land at all?
If my math's right, this is the equivalent of 1.5 gallons of gas?
Yeah, forests and prairies are worthless. Let's plow up everything.
0.38 gge (gallon of gasoline equivalent) per kg of starch. 27 kg would be 10.26 gge.
I’d be better than putting condos on it.
Don’t hold your breath........
The CO2 comes out of the air when the plant is grown, then returns to the air when the plant is burned or digested.
No net increase in CO2.
The problem, if such it is, arises when fossil fuels are burned, as they add net CO2 to the air.
And waste products aren’t necessarily useless or even lower value. See what mash from the ethanol production process does for cattle.
Our County Board of Supervisors declared our local National Forests a public nuisance due to fire and forest health dangers from heavy overgrowth and lack of forest management. We have miles of forests with small diameter trees as far as the eye can see that need serious thining. The costs of fuel reduction/thining without an offset are tremendous. The alternative is the costs of fighting rampant wildland fires, which is also tremendous.
Idea- lets use that biomass to produce much needed energy and offset the cost of thining. Wow - and it wouldn’t even affect our food supply. We could even use some of it to fuel heating and electrical costs of public facilities like schools and courthouses. There are even systems that are enclosed and have zero emissions.
And some places even pay you to take their waste products. :)
I’d appreciate some help from someone better at chemistry than I am. (Which ain’t hard.)
Are they trying to say that the starch is completely converted to CO2 and hydrogen? That there is no solid or liquid residue left at all?
You replied to the wrong person.
And cornstalks are biomass...
Couldn’t you also use a crop chosen for nitrogen fixation for biomass production, rotating it with other crops to help improve soil conditions?
We used to plant a winter crop of legumes to ‘fix’ the nitrogen in the soil and then would plow it under for the humus. We could have done a summer crop of cotton and then a winter crop of beans but the beans weren’t worth the price to harvest. Fertilizer was expensive when we were doing this so the free nitrogen and humus, not to mention the soil cover, offset the cost of planting beans.
Water byproduct, but otherwise, it looks like all gas!.........
Chick Peas make a great hummus............
Ha! I knew I should not have skipped lunch! That extra ‘m’ makes all the difference. :)
Thanks. I was envisioning the buildup of some kind of sludge in the gas tank, and trying to figure out how you’d go about cleaning it out. :)
I make my own hummus. Storebought just don’t taste right........
Sewage would also be biomass.
And not particularly tasty.
I make my own humus....and the plants seem to find it tasty. :)
I was thinking the same thing. This would basically be a sh!t eating, fart producing hydro machine suitable for putting at the city dump and sewage treatment facilities.
Controlling the reaction seems to be an issue. If you fill ‘er up with starch, you immediately start producing hydrogen. There needs to be a way to draw it off and store it (compressed?) even when the vehicle isn’t powered up.
What happens if you don’t get pure enough starch or enzymes, or you get the ratios mixed up? You slow down the reaction and could run out of fuel, even though you’ve got some in the tank. Lots of issues here, I think. But a nice start!
Non-comestible biomass can be grown on terrain unsuitable for food crops. A great deal of lumber is harvested from such terrain.
Forgive my naivete, but it looks like the enzyme reaction, freeing the Hydrogen molecules, takes place in the Phase #3 portion of the process. This may provide a natural petcock point for shutting down the reaction by denying fuel.
Remembering that this is conceived as a fuel cell application, not combustion, the fuel cell could still receive excess Hydrogen ions from the ongoing reaction.
What's left, if there is still excess could either be contained at low pressure, or drawn off onto the grid or a storage battery.
Perhaps I only prove that ignoraqnce is bliss, eh?
The Sunflower’s petals hold glass coils of photosynthetic algae and the resulting “sugars” are siphoned off. It also uses very little added water, which might become the next limiting quantity.
To me, the biggest problem would be that the enzymes, being a living organism would die, if deprived of food. The Hydrogen producer enzymes would need to be introduced/reintroduced/activated in Phase #3 of the Process Chart.
I can envision a starch being sold to the consumer that would have gone through phases #1 & #2 already, represented by (6 G6P) on the Chart, to which the Government would add highway taxes at the pump. The Phosphorilase and Phosphoglucomitase Enzymes might be dead of starvation, but who would care? They have already done their thing.
If what I am thinking is BS, I will need a Mulligan.
I tip my hat in respect and appreciation for your past deeds.
1. I have forgotten all the organic and inorganic chemistry I studied in H.S., but am willing to accept the above.
2. If the enzymes are expensive - it’s probably because they have significant energy costs in their production (or maybe there is an enzyme cartel out there...)
You’ve eaten algae lately?
Just because there’s a million posts saying biomass this or biomass that...there’s quite a bit of chose. Not all of them have to be corn, sugar, etc.
” Every source of biomass is grown on land and by methods that are used to grow food.
Devote more of that land to fuel production, and less of it is devoted to food production.
Right for the very few posts described on FR...which is mostly a political bias.
Wrong for the full context, and for those whom investigate the issue without care of political leaning.
Algae can be grown in the desert, and consumes an incredibly small amount of land [for high production]. Since cost are too high, it’s not yet viable....although it’s getting there. But once the method is done at a cost-efficiency, it could feed on carbon emissions (straight from coal plants), and water types don’t necessarily need to be salt-free.
They have a nice diagram, but it's a gross oversimplification. Still, I always thought enzymatic catalyzation was the way to go.
Enzymes aren’t organisms, they’re chemicals that help a reaction go forward. Catalysts. (Here’s your mulligan.)
The issue here is reaction rates. If all of this stuff is poured together in a “gas tank” and allowed to react, then the concentrations become so small that the production of H2 is greatly slowed because the each step’s reactants won’t “hook up” (to use a simple term) often enough to rapidly make the product necessary for the next step. If each reaction takes place in a successive vessel, then the issue becomes separation of the product from the enzymes to transfer it to the next vessel, which requires putting additional work into the system.
I hope I’m helping and not just thumping you on the head with chemistry...
Merci for the mercy!
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