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Go Back   World of Renewables - The World's #1 Online Renewable Energy Network! > Energy Conservation-Members only > Waste to Energy-Members only
Waste to Energy-Members only Generating electricity from garbage and pollution.

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Old 27th September 2007
DAGAFEED DAGAFEED is offline
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Lightbulb Garbage Is Potential Cellulosic Ethanol

Two-thirds of what we throw into our landfills today contains cellulose and thus potential fuel.


Can One Molecule Cure Our Addiction to Oil?

http://www.wired.com/science/planete...15-10/ff_plant

The Chemistry


On a blackboard, it looks so simple: Take a plant and extract the cellulose. Add some enzymes and convert the cellulose molecules into sugars. Ferment the sugar into alcohol. Then distill the alcohol into fuel. One, two, three, four and we're powering our cars with lawn cuttings, wood chips, and prairie grasses instead of Middle East oil.

Unfortunately, passing chemistry class doesn't mean acing economics. Scientists have long known how to turn trees into ethanol, but doing it profitably is another matter. We can run our cars on lawn cuttings today; we just can't do it at a price people are willing to pay.

The problem is cellulose. Found in plant cell walls, it's the most abundant naturally occurring organic molecule on the planet, a potentially limitless source of energy. But it's a tough molecule to break down. Bacteria and other microorganisms use specialized enzymes to do the job, scouring lawns, fields, and forest floors, hunting out cellulose and dining on it. Evolution has given other animals elegant ways to do the same: Cows, goats, and deer maintain a special stomach full of bugs to digest the molecule; termites harbor hundreds of unique microorganisms in their guts that help them process it. For scientists, though, figuring out how to convert cellulose into a usable form on a budget driven by gas-pump prices has been neither elegant nor easy. To tap that potential energy, they're harnessing nature's tools, tweaking them in the lab to make them work much faster than nature intended.

While researchers work to bring down the costs of alternative energy sources, in the past two years policymakers have finally reached consensus that it's time to move past oil. The reasoning varies reducing our dependence on unstable oil-producing regions, cutting greenhouse gases, avoiding ever-increasing prices but it's clear that the US needs to replace billions of gallons of gasoline with alternative fuels, and fast. Even oil industry veteran George W. Bush has declared that "America is addicted to oil" and set a target of replacing 20 percent of the nation's annual gasoline consumption 35 billion gallons with renewable fuels by 2017.

But how? Hydrogen is too far-out, and it's no easy task to power our cars with wind- or solar-generated electricity. The answer, then, is ethanol. Unfortunately, the ethanol we can make today from corn kernels is a mediocre fuel source. Corn ethanol is easier to produce than the cellulosic kind (convert the sugar to alcohol and you're basically done), but it generates at best 30 percent more energy than is required to grow and process the corn hardly worth the trouble. Plus, the crop's fertilizer- intensive cultivation pollutes waterways, and increased demand drives up food costs (corn prices doubled last year). And anyway, the corn ethanol industry is projected to produce, at most, the equivalent of only 15 billion gallons of fuel by 2017. "We can't make 35 billion gallons' worth of gasoline out of ethanol from corn," says Dartmouth engineering and biology professor Lee Lynd, "and we probably don't want to."

Cellulosic ethanol, in theory, is a much better bet. Most of the plant species suitable for producing this kind of ethanol like switchgrass, a fast- growing plant found throughout the Great Plains, and farmed poplar trees aren't food crops. And according to a joint study by the US Departments of Agriculture and Energy, we can sustainably grow more than 1 billion tons of such biomass on available farmland, using minimal fertilizer. In fact, about two-thirds of what we throw into our landfills today contains cellulose and thus potential fuel. Better still: Cellulosic ethanol yields roughly 80 percent more energy than is required to grow and convert it.

So a wave of public and private funding, bringing newfound optimism, is pouring into research labs. Venture capitalists have invested hundreds of millions of dollars in cellulosic-technology startups. BP has announced that it's giving $500 million for an Energy Biosciences Institute run by the University of Illinois and UC Berkeley. The Department of Energy pledged $385 million to six companies building cellulosic demonstration plants. In June the DOE added awards for three $125 million bioenergy centers to pursue new research on cellulosic biofuels.

Last edited by DAGAFEED; 27th September 2007 at 08:16 PM.
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Old 2nd October 2007
KateMcCridhe KateMcCridhe is offline
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Until very recently (about a month or so ago), Tulsa had a power plant that was powered by refuse.

The contract was not renewed.

Heck, I'd only heard of the plant a few days before the thing was shut down. I couldn't believe they were so silly as to drop that contract! The benefits were manyfold, not only providing low cost energy, but also easing the strain on land fills, et al.

Anybody know any thing about that one?
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