Tuesday, November 20, 2007

Some mitigation strategies for agriculture -- with implications for adaptation

Cleantech Collective, by Jonathan Smith, or "jcwinnie": As soon as release of the preliminary report was announced, Biopact heralded IPCC advocacy for BECS (Bio Energy with Carbon Storage), a “low-tech” initiative that AG readers know as agri-char. The Synthesis Report includes a list of key mitigation technologies and practices. Currently commercially available technologies and practices that the IPCC see as key to the mitigation of GHG emissions from the agriculture sector include:
  1. Improved crop and grazing land management to increase soil carbon storage;
  2. Restoration of cultivated peaty soils and degraded lands;
  3. Improved rice cultivation techniques;
  4. Improved livestock and manure management to reduce CH4 emissions;
  5. Improved nitrogen fertilizer application techniques to reduce N2O emissions;
  6. Dedicated energy crops to replace fossil fuel use;
  7. Improved energy efficiency in agricultural operations.

Substituting coal with biomass as a fuel in the generation of electric power need not require dedicated energy crops to reduce GHG emissions. In the United States, in terms of grazing land management that could increase the capture of carbon dioxide, some scientists have suggested the growing and harvesting of “diverse mixtures of long-lived, deep-rooted native plants on damaged, unproductive farmland.”

“We have a vision of restoring a lot of prairie throughout the Midwest, and having something that will be mowed every year for hay and then either pelletized and burned, or converted into ethanol,” says University of Minnesota Professor David Tilman, who has conducted prairie grass research at the Cedar Creek Natural History Area for 12 years. A world-renowned ecologist, Tilman is lead author of a new study about prairie grasses as a biofuel source.

At least one study commissioned by the National Renewable Energy Laboratory indicates that using biomass to generate electricity could result in a 47% decrease in green house gases compared with the use of petroleum. In terms of soil ecology, some research suggest that is more beneficial when “they harvest the grass after a killing frost, so that virtually all the nutrients have left the plant body which is harvested, and are left in the root bit which is left on site.”

While switchgrass, Miscanthus giganteus and scores of other plants are now being studied for energy production, such ligno-cellulosic crops require farmers to adapt their current operations. Planting, cultivating and harvesting such dedicated energy crops may require adjustments to existing equipment or different equipment than farmers already may have. While argument exists over whether such energy crops require more processing by the companies that purchase bio-energy crops; generally collection and storage are different.

E3 Biofuels Cycle

Some would argue that agricultural waste is a better way to increase efficiency. On the other hand, the cost of preparation and increasing transportation costs have negative impacts upon efficient conversion of agricultural waste, e.g., stover1. Furthermore, farmers are likely to find it difficult to compete with two other sources of supply, forestry waste and municipal solid waste, for fee-based supply of thermoelectric plants, since the handling of waste is a more established expense for such industries, whereas farmland can benefit from recycling of the waste in situ.

On the other hand, waste that is a byproduct from the processing of harvested crops, e.g., bagasse, rice husks, chaff, etc., and can be done with little additional ongoing effort, then such conversion of waste to energy would seem advisable.

The most controversial recommendation for U.S. agriculture is Improved livestock and manure management. The meat industry, i.e., huge-scale confined-animal feedlot operation (CAFO) players like Tyson and Smithfield, is resisting such melioration, which would translate not only to improved air quality, but also improved water quality. A less evident, yet significantly great resistance comes from fossil fuel dominance over agriculture. Fertilizers, herbicides and pesticides require petroleum and the processing of agricultural products depends upon coal and natural gas.
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  1. 1Corn Stover Collection Project

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