Cellulosic fuel ethanol plant begins production; organisms help
-- Control Engineering, 11/1/2009
Coskata Inc. has started production of fuel ethanol at its new semi-commercial plant in Madison, PA. This facility is designed to demonstrate the company’s new flex-ethanol process—which can manufacture ethanol from virtually any cellulose-based feedstock, ranging from sustainable energy crops to construction waste.
Coskata’s facility will be producing ethanol from numerous feedstocks, including wood biomass, agricultural waste, sustainable energy crops, and construction waste. This flexible approach is enabled by Westinghouse Plasma Corporation (WPC), a wholly owned subsidiary of Alter NRG, and its plasma gasification technology. The process uses a three-step conversion that centers around designer microorganisms:
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Gasification: Heat breaks chemical bonds in the feedstock and completely converts organic matter into synthesis gas (syngas), primarily a mixture of carbon monoxide, hydrogen, and carbon dioxide. The syngas passes through a scrubber to remove particulates, providing recoverable energy in the cooling process.
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Fermentation: The syngas is sent to a proprietary bioreactor where patented microorganisms consume both carbon monoxide and hydrogen, simultaneously. As the syngas passes through the bioreactor, the microorganisms consume it as food and create ethanol. Ethanol and water then exit the bioreactor.
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Separation: Ethanol is separated from the water using traditional distillation or membrane permeation. Water is recycled back into the bioreactor, contributing to the process’ conservation advantages. The final result is fuel-grade ethanol.
Coskata’s technology, as demonstrated through Project Lighthouse, is said to reduce greenhouse gases by as much as 96% over conventional gasoline, while using less than half the water that it takes to get a gallon of gasoline. In addition, the company’s ethanol is as much as seven-times as energy positive as the fossil fuel used in the process, addressing many inefficiency concerns related to traditional grain-based approaches.
The specific biological fermentation technology used in the process is ethanol-specific and enzyme independent, contributing to high energy conversion rates and ethanol yields. Coskata says the process requires no additional chemicals or pre-treatments, which streamlines operational costs and should allow it to compete directly with conventional gasoline without long-term government subsidies.
“The integrated biorefinery—utilizing Westinghouse Plasma Gasification on the front end and Coskata’s syngas-to-biofuels conversion process on the back end —serves as an excellent example of two companies working together to deliver a viable process to the biofuel market,” said Mark Montemurro, president and CEO of Alter NRG. “We’re excited to be delivering the feedstock flexibility to Coskata’s efficient and affordable process.”
The facility is a demonstration of minimum-scale engineering, which means it is the smallest size that will still allow the company to scale directly to 50 and 100 million gallon-per-year facilities. A portion of the fuel produced at the new facility will be provided to General Motors for use at its Milford Proving Grounds to advance flex-fuel engine technology.
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