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Alternative Energies Title: How Stinky Gas Can Save the Earth (Cow Farts It elicits giggles and grimaces when it emanates from cows' rear ends, but methane represents a serious threat -- it's a greenhouse gas 20 times more potent than carbon dioxide. Taking the "dross into gold" dictum to a whole new level, Velocys of Plain City, Ohio, is capturing the environmental pollutant and turning it into liquid fuel for heating or transportation. Though some blame methane's prevalence on barnyard inhabitants, most of it is a byproduct of human activities such as mining and trash burial. It's prevalent in underground caves where coal is found, and anaerobic conditions inside landfills foster decomposition that generates the gas. Much of it is contaminated with nitrogen. "Nitrogen and methane molecules are both physically inert, so neither one wants to react with other compounds," says Steven Perry, a chemical engineer at Velocys. "They're also similar in size, so it's hard to filter one from the other." Velocys has devised a way to separate nitrogen from methane by forcing it through tiny channels less than a millimeter wide. Engineers add a compound such as porous carbon to these microchannels, then cool them. The carbon binds to methane molecules, holding them in place inside the channels. While methane molecules get stuck, nitrogen passes straight through. Engineers then warm the channels, allowing the methane to detach from the carbon. The approach was presented at the American Institute of Chemical Engineers conference in San Francisco last month. The microchannel treatment can transform methane from 70 percent purity to over 90 percent purity, making it suitable as an energy source for homes and, potentially, as automobile fuel. "This technology takes emissions from natural gas streams and turns them into a form that's usable," says Dawn Deel of the National Energy Technology Laboratory, which is collaborating with Velocys on the project. Though Velocys continues to refine its methane-purification techniques, company executives predict the system will be ready for large-scale use in three years. The project seems to have brought legislators, tycoons and environmentalists into agreement. Ohio Rep. Deborah Pryce supports the company. Others are on board because the company's strategy can turn a liability into an asset. "In total, the methane emitted worldwide every year amounts to 17 million metric tons," says Jeff McDaniel, Velocys' business development manager. "That's the potential amount of greenhouse gas reduction we could achieve with this technology."
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