Wednesday, February 13, 2008

Trash to Ethanol


A group in California is trying their luck at ethanol production from trash wastes. Bluefire Ethanol plans to open its first plant in Lancaster, California later this year and will construct this plant right on top of a landfill. The researchers plan to use this as a pilot ethanol plant to see if the process works. There is enough interest in the idea that the Department of Energy (DOE) will seek to invest $40 million in the ethanol plant that will use the cellulose in thrown out materials such as paper that would otherwise go into the landfill but this time it will be used to make ethanol.

Although skeptical at first, the idea might actually be pretty ingenious. They must use an acid pre-treatment step (composed of sulfuric acid) in order to liberate the cellulose (sugars) that are in the landfill wastes. This process can be expensive, and thought to be inferior to gasification because none of the lignin that might be present will be used. But it is in a different part of the processing that this plant might have a "leg-up." The project plans to use the lignin that can't be converted into usable sugars to burn in order to generate at least 70% of the heat and electricity to run the plant (instead of using coal or natural gas). For the remaining energy, the plant will harvest the methane gas produced at the landfill to power the remaining parts of the plant. This could not only save the company money and protect it from volatility, but it also significantly reduces the ratio of fossil fuels used to ethanol produced making the entire process that much more environmentally friendly.

Bluefire Ethanol is not alone in taking a hard look at cellulosic ethanol -- Range Fuels in Georgia is in the process of testing a wood to ethanol technology. Coskata, (as well as others), are looking into the same idea but using gasification as a way to liberate more usable sugars. With Bluefire only building a 22 million gallon per year ethanol plant, it'll be interesting to see what their preliminary results are as to whether the process is economical. Once that is done, the process will have to be scaled up to see whether the process can handle a 100 million gallon per year ethanol plant.


Below is Bluefire's engineering diagram:

http://thefraserdomain.typepad.com/photos/uncategorized/bluefuelarkenol_flow_diagram.gif



For the original article:

http://www.sciam.com/article.cfm?id=trash-based-biofuels

1 comment:

mus302 said...

Although the process may be more expensive than the process to convert corn to ethanol, the feedstock will be much less. So it will be interesting to see how the economics turns out.