Garbage Into Fuel Venture Gains Momentum
NYTimes.com Green, A Blog About Energy and the Environment
Matthew L. Wald, June 1, 2011
Enerkem, a Montreal company that makes ethanol from old utility poles and household garbage, Valero, a major independent oil refiner, and Waste Management, a trash-hauling company, are investing big bucks to make ethanol from garbage.
Enerkem is starting up a plant near Sherbrooke, Quebec, with a capacity of 1.3 million gallons a year, and it is building another in Edmonton, Alberta, that could produce 10 million gallons. And it recently received a $50 million grant and loan guarantee from the US Department of Energy for a third plant, near Tupelo, Mississippi, that would be a twin of the Edmonton plant. Those two plants would each consume 100,000 tons of garbage a year, company executives say.
In Edmonton, the company has a 25-year contract to accept municipal solid waste. After separating out recyclable materials, it shreds the waste and heats it to around 400 degrees Celsius, or about 750 degrees Fahrenheit. At that temperature, the waste gives off a gas that includes hydrogen and carbon monoxide. Enerkem scrubs out the impurities, including carbon dioxide, and runs the gas over a catalyst, which converts it to methanol. The methanol can be turned into ethanol or a variety of other chemical feedstocks. The product meets the federal definition of an advanced cellulosic biofuel, meaning a fuel that comes from plant material but not from food.
Making ethanol from garbage entails sharply lower carbon dioxide emissions than making it from corn, which needs large amounts of natural gas. The Enerkem process relies on the heat given off by the process itself so that no fossil fuels are burned except during the start-up. Starting up requires burning some natural gas or propane, but once running, the gasification process produces excess heat that can be used to boil water and make electricity.
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