Earlier this year, headlines were made on the announcement of biotech start-up Coskata promising to revolutionize the production of ethanol with a process that could use a variety of feedstocks, ranging from wood chips and switchgrass, to old tires, and even directly from municipal waste. Most importantly, it did not rely on corn or other food stocks in order to produce fuel. At the time, Coskata was predicting an aggressive timeline, with a pilot demonstration plant to begin operation in 2009, and a first full-scale plant to be underway by 2011.
Last week Coskata announced the location for their pilot demonstration plant, a facility that will begin producing 40,000 gallons of ethanol per year, starting in 2009. While that is only a tiny drop in the proverbial bucket, it’s another step along the path to having a full-scale plant in operation and producing 50 to 100 million gallons of ethanol per year.
Unlike other ethanol producers, the Coskata process will not be producing ethanol from fermenting corn, but instead will be incinerating carbon bearing materials in a plasma arc furnace to produce syngas, a mixture of hydrogen and carbon monoxide, which is fed into the bioreactors where anaerobic bacteria consume the gasses and produce ethanol.
This pilot plant will be using a version of the plasma gasification system to break down the feedstock and produce the syngas the microbes feed upon to produce ethanol. Interestingly enough, the site for the pilot plant is on the grounds of the Westinghouse Plasma Center, near Pittsburgh PA. 25 years ago General Motors (a partner with Coskata on developing and promoting their ethanol manufacturing process) and Westinghouse Electric developed a high-volume plasma torch furnace, called a plasma arc cupola in order to produce molten iron for automotive engine blocks, crankshafts, and brake components. And now, this same technology is being used to provide fuel for transportation.
The feedstock for this pilot plant will include a variety of source materials, including some municipal waste. Presumably, as a pilot plant, they will want to test a range of feedstocks to evaluate performance and efficiency with a variety of materials.
While the plasma arc completely incinerates the materials fed into the furnace, it should not be confused with ordinary trash incineration. The plasma arc strips materials down to their component atoms at extremely high temperatures, and the entire output stream is contained, with the syngas being fed into the Coskata system for fuel production, and other materials forming a slag that can be processed to extract useful minerals. Unlike conventional trash incineration, there is no exhaust from this form of incineration being released into the atmosphere. It stays completely self contained.
And though the Coskata pilot plant may or may not be set up in the same fashion as the StarTech system, the plasma torch can actually draw enough energy for its operation from a inline generator using the heat from the superheated syngas to provide the electricity to run the torch. As long as material is being fed into the system, it will remain self-sustaining. The analysis of this system indicates a ratio of 8 units of energy produced for every unit of energy used to produce it. This is far superior to food-stock based ethanol production methods, as well as some more traditional extraction methods.
Cross-posted at EcoGeek.org
via: GM Next Blog