Biofuels getting bad press in the US

Ethanol: According to this US Department of Agriculture report from 2002 the average amount of water used in the production of one gallon of ethanol was 4.7 gallons. The report was based on a survey of dry mill ethanol plants and also states that the average use of electricity is 1.19 kilowatt hours (kWh) of electricity per gallon of ethanol produced. While the above statistics are starting to raise eyebrows in the US it is this Stamford University report that is the current spoiler for ethanol enthusiasts. It says that if every vehicle in the US ran on E85 the result would likely be slightly higher ozone-related mortality, hospitalisation, and asthma (9% higher in Los Angeles and 4% higher in the US as a whole).

Finally there is the food price issue that is now being reported in Australia. Ethanol production in the US uses corn seed as its primary feed stock. The ever increasing demand for ethanol has started to raise the price of corn which in term raises the price of corn based foods.

Biodiesel: According to Science Daily, when analysts at SRI Consulting have compared the emissions of greenhouse gases from biodiesel and fossil diesel across their overall life cycles from production to combustion in cars. The results show that biodiesel derived from rapeseed grown on dedicated farmland emits nearly the same amount of greenhouse gas emissions (defined as CO2 equivalents) per km driven as does conventional diesel.

Fossil diesel emits 85% of its greenhouse gases when burnt in an engine. By contrast, two-thirds of the emissions produced by rapeseed derived biodiesel occur during farming of the crop, when cropland emits nitrous oxide which is 200 to 300 times more potent than CO2 as a greenhouse gas.

New biofuels: Biobutanol and cellulosic ethanol are both starting to attract attention for more positive reasons. Unlike ethanol, the energy density of biobutanol is much closer to that of petrol, it blends with petrol more easily and is less corrosive and therefore easier to transport. In blends with diesel or petrol, biobutanol is less likely to separate than ethanol if the fuel is contaminated with water.

BP and DuPont have announced a partnership to develop biobutanol. The first DuPont-BP biobutanol manufacturing facility in the UK will use sugar beet as the feedstock and should be functioning by the end of 2007. Future biobutanol manufacturing facilities however, could use biomass or cellulosic feedstocks from fast growing energy crops such as grasses or even agricultural by products such as straw and corn stalks.

This leads us to cellulosic ethanol, the major benefit of which is that it doesn’t rely on food crops for feed stock. Cellulosic ethanol is chemically identical to ethanol made from corn or sugar feedstock. However, cellulosic ethanol can be made from a great diversity of biomass including waste from urban, agricultural, and forestry sources thereby enabling it be produced without raising the price of food.


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