A negative-carbon corn ethanol plant?

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"A negative-carbon corn ethanol plant?"

I am not the biggest fan of corn ethanol. But I am the biggest fan of cogeneration, also known as combined heat and power, CHP (well, maybe the second biggest fan). It is probably the single most overlooked strategy for sharply cutting greenhouse gas emissions while reducing overall energy costs.

chp-small.pngNow a new EPA report finds that running an ethanol plant on natural gas CHP can, with the right design, result in negative net CO2 emissions (click on figure to enlarge).

Important caveat: Impact of Combined Heat and Power on Energy Use and Carbon Emissions in the Dry Mill Ethanol Process does NOT examine the energy consumed (or emissions generated) from growing and harvesting the corn or from transporting the corn or ethanol. Still, with CHP, corn ethanol can actually generate significant CO2 reductions compared to gasoline.

If Congress is serious about promoting ethanol in a manner that actually reduces GHGs, they should require all new ethanol plants to cogenerate.

[UPDATE: Link to EPA study is fixed!]

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5 Responses to A negative-carbon corn ethanol plant?

  1. Peter says:

    Do you have a link to the EPA report?

  2. Joe says:

    My apologies. Link is fixed.

  3. D-pop says:

    Using corn for ethanol, especially a carbon-neutral process, would be an excellent strategy. I would also like to see soybeans used for this. Widespread diversion of corn and soybeans away from the food chain would have huge benefits beyond a reduction in CO2 emissions.

    Corn and soy are not fit for human consumption and are not even digestible without a lot of processing. Reducing the amount of corn oil, corn syrup, soybean oil and soy protein in the human diet would result in a reduction of heart disease, cancer, obesity, allergies, and many other health problems.

    It would raise the price of meat, reducing meat production and consumption. Meat production is a big source of greenhouse gases. Over-consumption of meat is a big source of health problems.

    It would raise the price of the very foods that are highest in corn and soy products, shifting consumption to healthier alternatives.

    It would raise the price of some alcoholic beverages, thereby reducing consumption, another benefit to society.

    An overall reduction in caloric intake for the average human would also result in a lower birthrate, which over time would have still more benefits to the planet.

    Have you talked on this blog about industrial hemp? That is another crop that would have huge potential for use in cellulosic ethanol, replacing forest products, as well as for food (hemp seeds are higher in oil and protein than either corn OR soy).

    Keep up the good work.

  4. Too bad that carbon is the least-problematic aspect of corn ethanol or soy biodiesel from a GHG standpoint.
    see:
    http://www.atmos-chem-phys-discuss.net/7/11191/2007/acpd-7-11191-2007.pdf
    http://gristmill.grist.org/story/2007/9/24/112556/658

    There is some pretty damning work coming out by some extremely well qualified experts in atmospheric chemistry that is showing that the nitrogen fertilizers used in corn and soy agriculture, in addition to thier already awful ecosystem effects on the ground, when ejected into the air through the lifecycle of biofuels production actually result in a lifecycle GHG emissions footprint that is as much as 50% worse than conventional petro-gasoline in the case of corn ehtanol, and as much as 70% worse than petro-diesel in the case of rapeseed biodiesel.

    Bring on the Jatropha and the biomass synthetic fuels.