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Driving on Starch
Roland Piquepaille writes "Using sugar contained in corn or potatoes to build hydrogen-powered fuel cells has already been done. But now, a team of U.S. researchers has developed a new sugar-to-hydrogen technology. Why not put the starch inside the tank of your car? With the help of 13 specific enzymes, 'a car with an approximately 12-gallon tank could hold 27 kilograms (kg) of starch, which is the equivalent of 4 kg of hydrogen. The range would be more than 300 miles, estimates one of the researchers. One kg of starch will produce the same energy output as 1.12 kg (0.38 gallons) of gasoline.' The beauty behind this idea is that no special infrastructure would be needed. Starch could be distributed by your local grocery store."
Wouldn't that be a lot of starch? I mean, wouldn't we then have a shortage of it? I know it's more renewable than gas, but could they even produce enough? They're having a hard enough time with 10% corn for gas. 12 gallons of starch is like, 110 or so bags of starch at the store...
Now, I know this probably will never get seen by anyone, but none of the posts so far were appropriate to reply to.
I am actually a bioengineer, and I'm actually working in this field, trying to convert ethanol into hydrogen.
And I can say, this process looks excellent. Finding natural enzymes that do the conversion makes everything enormously easier.
Here's the deal. Ethanol has slightly more energy than straight sugar, because the fermentation adds energy to the system. That added energy is negligible in comparison to the total energy. However, you lose a butt-load of energy because you have to heat the sugar up in order to ferment it, deal with transportation costs for the crops, and if you're using it as an additive (instead of reforming 20-25% ethanol in water directly), distill it to 100%, which uses a ridiculous amount of energy (10 times more to get it from 95-100 than from 20-95). However, the plus side is that ethanol is a pretty high energy density liquid, about 85% that of gasoline, and much higher energy density than compressed hydrogen gas. So, with an ethanol+water mixture, you end up getting 6 H2 out of every one etOH molecule. Pretty durn good. (if you think I'm an idiot because I have more hydrogen coming out than are on an ethanol molecule, look up steam reforming instead of making yourself look like a fool)
However, at the end of the day, it's extremely questionable whether or not ethanol itself is net energy positive, because of all the energy that goes into producing it (even though the liquid itself increases in energy density). Sugar, however, is less refined, and so less energy goes into making it. The idea is this -- if the net energy is negative, then you're still using more fossil fuels than you save. But if sugar is energy positive, then you can use 1kg of sugar to produce 2kg of sugar, and use that to make 4kg of sugar, and so on.
Sure, you have to pay attention to the problems of rising food costs. But starch? Don't worry about it, it'll be more efficient than gasoline, and it'll be more efficient than ethanol. You're talking a 3x fold improvement on efficiency right off the bat because it's a fuel cell instead of an I.C.E. Now, your sugar production has to be net energy positive, so multiply that factor (guess would be around 2-3) times the 3x fold efficiency improvement in the fuel cell and you're using 6-9 times less energy to produce the same amount of work. The economy will figure out the rest -- hell, you can get starch out of all sorts of crop waste way more easily than you can get ethanol out of them.