Posted: Mon Aug 16, 2004 9:09 pm Post subject: [Alcohol 7] Ethanol as carrier for H2 for use in fuel cells
Ethanol as carrier for hydrogen for use in fuel cells
Hi y'all. There's some holes in this guy's theory, but he has a couple points that are worth noting. One is that a lot of energy can be saved by getting away from energy-intensive mechanical and thermal feedstock refining techniques and getting down to the molecular level to do refining work. I take him at his word about this Iogen microbial process, which I know nada about.
What do you all make of this scheme? I emailed the author asking if he had done any prelim EROEI calcs on the net process.
I don't doubt that the microbe breaks down cellulose, I am more curious as to what it is likely to do in the wild.
I don't think ceramics at 600 degrees are likely to make the best internals for hydrogen cars. Here's some guys who claim they've got the solution: solid hydrogen.
I don't doubt that the microbe breaks down cellulose, I am more curious as to what it is likely to do in the wild.
I don't think ceramics at 600 degrees are likely to make the best internals for hydrogen cars. Here's some guys who claim they've got the solution: solid hydrogen.
see {url removed - OilBurner}
Solid hydrogen? Codswallop! Metal hydrides have been proposed since decades and are notoriously inefficient, if somewhat easier to handle. However, it doesn't get round the basic fact that we have to produce hydrogen without carbon. At the moment, this means electrolysis. Are we willing to have over a thousand more nuclear power stations dotted round the world to satisfy the demand for a clean fuel? _________________ Devil
Joined: May 26, 2004 Posts: 309 Location: Ontario, Canada
Posted: Tue Aug 17, 2004 9:57 pm Post subject:
Forget the hydrogen for a sec - read exactly what they're saying about the process. It sounds fundamentally different from typical biofuels, and amazing...
Quote:
Worse, making ethanol is a hideous waste of energy. Traditional ethanol is made from fruit, primarily corn kernels, while the rest of the plant is either burned or plowed back into the soil. After its arrival at the ethanol refinery, the corn is mashed, producing a gooey soup. Then it is placed in high temperature fermenters that break down the corn sugar into ethanol and water; a series of boiling and condensing processes squeezes out most of the water, leaving fuel-grade ethanol, which is essentially 199-proof vodka. All that work takes up a lot of energy--more energy, in fact, than is contained in the final product. The farming and refining process needed to produce one gallon of ethanol requires the equivalent of 1.3 gallons of gasoline. "Corn ethanol just isn't efficient and people will be left hungry if we use our croplands to grow fuel instead of food," says Pimentel. "It's just a bad idea."
As currently produced, ethanol is also more expensive than gas. Thanks to an intensive Department of Energy research program costing billions of dollars over the last three decades, scientists have determined how to make ethanol from corn as cheaply as possible and make it burn inside an engine as cleanly as possible. But the gasoline-ethanol mix for which most American cars are equipped--known as E85, because it is composed of 85 percent ethanol and 15 percent gas--still costs at least $2.20 per gallon. Even now, with gasoline prices at a relatively high $2 a gallon, that's no bargain.
Waste lines
Two new technologies, however, have the potential to make ethanol fuels much more practical. The first is a method for producing ethanol not from corn kernels, but from the plant's stalk, roots and leaves, known as cellulosic material. So-called cellulosic ethanol has been around for years, but breaking down the cellulose to make it fermentable was inefficient, expensive, and manufactured a fair amount of pollution. A Canadian biotechnology firm called Iogen, however, has developed a genetically-engineered microbe that processes the cellulose much more easily. (A European company, Novozymes, recently reported that it had developed a similar process.) Cellulosic ethanol made from stalks and husks still has to be fermented. But because it uses cast-off waste products of food that's already being grown, Iogen's process saves on both raw materials (depending on wholesale prices, raw corn can represent anywhere from 50 to 70 percent of the wholesale price of traditional ethanol) and energy costs.
According to estimates done by Charles J. Wyman, a Dartmouth environmental engineer who has consulted for ethanol firms and is an expert in refinery technology, the new technologies could bring the price of cellulosic ethanol down to between 60 and 80 cents per gasoline-gallon-equivalent. (Because ethanol produces about a third less energy than gasoline when burned in an internal combustion engine, you need a third more ethanol than gasoline to drive the car the same distance.) And that's within the price range of refined gasoline, which runs between 25 cents per gallon drawn from Saudi oil and 75 cents per gallon for Wyoming oil. "It's getting to the point where the economic argument is just screaming at us," says Wyman. Iogen is already betting on the future: In partnership with Royal Dutch Shell, the company has begun construction on a plant that, by 2006, is expected to produce about 100 million gallons of ethanol per year.
The prospect of cheap cellulosic ethanol makes it possible to envision a very different energy landscape. Since it doesn't require fuel-intensive refining, Iogen's product would provide a net energy gain. If it becomes competitive with gasoline, we could begin substituting cellulosic ethanol for imported gas. According to an estimate by the consulting firm Burrill Co., if the waste products of all American farms were converted into cellulosic ethanol (a long-term, best-case scenario to be sure) it would provide 25 percent of all the energy needed to run our transportation system--about the same percentage which we import today from Venezuela and the Persian Gulf combined. (The rest currently comes from U.S. sources, Canada, and Mexico.)
And while traditional ethanol production requires us to burn our own food, cellulosic production does not. Indeed, a number of energy crops including poplar trees and sugar beets can be grown on land unsuitable for food production. Most intriguing of all is switchgrass, a hardy North American plant that can be raised without irrigation and harvested with a low-labor process similar to mowing the lawn. In other words, it requires very little energy to bring to harvest compared with ethanol's traditional corn. According to Cornell's Pimentel, roughly 15 percent of the North American continent consists of land that is unsuitable for food farming but workable for switchgrass cultivation. Given the typical energy yield of switchgrass, a rough calculation indicates that if all that land were planted with switchgrass, we could replace every single gallon of gas consumed in the United States with a gallon of inexpensive, domestically produced, and more environmentally-friendly cellulosic ethanol.
So they can affordably use microbes to break down the cellulose, producing ethanol with a net energy gain, and they can use non-food farm waste and crops grown on land that's unsuited to farming, so we don't run into the food-or-fuel dilemna. I mean, it sounds like a magic bullet here - maybe not to give everyone in America a car, fine, but to keep a decent level of mechanized transit and construction going? Running cars on 85% or 100% ethanol is tough but it can be done.
And then yes, it dovetails nicely into hydrogen later, but forget that for a sec. The Iogen process on it's own needs more study than I'd realized. I thought it was a typical biofuels operation. Must be some kind of a catch. _________________ "Our forces are now closer to the center of Baghdad than most American commuters are to their downtown office."
--Defense Secretary Donald Rumsfeld, April 2003
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