“Kitchen Stove” Biorefinery Goes from Grass to Gasoline in One Hour

February 26th, 2012 by Tina Casey





The California biofuel company Cool Planet BioFuels has announced the successful test of a pilot biorefinery that can convert an acre of the giant grass miscanthus into gasoline at the rate of 4,000 gallons per acre. You read that right – the process yields straight, drop-in quality gasoline that is chemically identical to its petroleum-based cousin.

A word about gallons per acre

According to Cool Planet, 4,000 gallons/acre means that the process generates about twelve times the yield of a corn ethanol refinery. However, the company cautions that this figure represents optimal growing conditions. In the real world, given routine growing conditions for miscanthus in appropriate regions (primarily the Midwest), Cool Planet estimates a typical yield of 3,000 gallons per acre.

Cool Planet also notes that as an added benefit, some carbon could be diverted from the refining process and used as a kind of “terra preta” to enhance crop soil. That would decrease the production of gasoline but the yield is still pretty impressive. The company claims that the process will work on switchgrass and other woody biomass, and even agricultural waste will yield about 1,000 gallons per acre.

“Kitchen stove” biorefining

Cool Planet’s biorefining process requires a relatively low energy input at every stage. That starts with growing, since Miscanthus is a hardy perennial that does not require annual planting. The biomass prep stage is low-impact because the refining process is designed for crops that can be air dried to the appropriate moisture content while still in the field. No additional treatment is needed other than grinding. As for the refining, Cool Planet describes the process temperature as comparable to a “kitchen stovetop,” and the pressure barely tops that of a portable tire inflater. All in all, the conversion process from dried biomass to gasoline takes about one hour.

Thisclose to biofuel parity with petroleum

Taking into account only the feedstock and energy input, Cool Planet estimates that its biogasoline comes in at less than 60 cents per gallon, based on current commodity prices. That’s not what you would pay at the pump, obviously, but it does indicate that biogasoline is breathing down petroleum’s neck in terms of ahceiving price parity.

That day could be coming sooner rather than later. Cool Planet is readying a modular biorefinery design that can be planted just about anywhere that feedstock is available, and expects initial installations to begin within the next two years.

After that, it’s just a matter of sitting back and watching the grass grow.

Image: License Some rights reserved by Anton Novoselov.

Follow Tina Casey on Twitter: @TinaMCasey.









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