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Published online 9 April 2008 | Nature | doi:10.1038/452670b
Advanced biofuels face an uncertain future
Aggressive US mandate may do more harm than good.
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It's almost as if we were trying to find an alternative and viable biofuel source that would leave us still dependent on fossil fuels and wouldn't hold a significant advantage in either economic or environmental cost for its production. Why isn't all the focus going towards using biowaste as the ultimate source of bioenergy that would help ease our transition away from nonrenewable sources of energy and reduce GHG emissions? If we were able to take all the energy retained in agricultural waste and sewage - we'd not only be finding a solution our increasing poop pollution and the biohazards contained therein, we'd remove the methane produced by its decomposition - and we'd have a lot of free energy that neither needs acres of land to grow nor take food out of the mouths of hungry people.
I live in corn country and I can assure you that the agricultural waste, particularly the poop (after the corn and silage has gone through cows), goes back onto the corn fields as fertilizer. Nothing gets wasted. I wonder if they factored into the equation the significant amount of CO2 that the corn plants take up as they are growing, in addition to the reduction corn ethanol use represents as a substitution for traditional fossil fuels--and the energy required to recover fossil fuels from underground (not to mention transport them from overseas)? Lets keep our fuel expenditures domestic, and provide our own farmers with a new lucrative cash crop. And who says production of methane is a bad thing? we just need to find a way to recover it cheaply for use as a further fuel source.
(in response to Eysinga) Methane is a more potent GHG contributer (relative to CO2) - and among the worst contributers to climate change. I had writen a proposal highlighting the use of anerobic digestors for rural communities in India that could benefit from removing biohazardous human waste (from liquid human sewage) that would provide clean water, energy, and remove problematic waste at the same time. In Vancouver, we have a wonderful land-fill to gas plant in operation where we capture the released methane from decomposing organic waste from our landfill - which provides energy for thousands of homes and supplements our hydro-energy. The excess energy produced from the plant is used by neighboring greenhouses owned by ConAgra - making it fairly efficient and lucrative.
Corn-ethanol is expensive and sugarcane-ethanol is cheeper. If US remove the taxes imposed to the brazillian ethanol the price of the liquid fluel in US would go down and US would have enogh ethanol till cellulose works.
It may be considered debatable or even questionable to use food crops to produce an energy fuel (e.g. maize, sugar). However producing biogas from "Poop" sounds very sensible indeed. And there are other sources of renewable energy, e.g geothermal energy, river current energy, etc. These may be generated close to where the farms are located.
Quote from Eysinga "I wonder if they factored into the equation the significant amount of CO2 that the corn plants take up as they are growing ..." Well, yeah, the CO2 would end up in the ethanol and the agricultural waste, which would then be returned to the atmosphere upon utilization. That's the WHOLE idea behind these biofuels. They're more or less carbon neutral, but never carbon-negative (unless we decide never to use the ethanol and just store them away).
H Tse, your quote "That's the WHOLE idea behind these biofuels. They're more or less carbon neutral, but never carbon-negative" would be true if it did not require natural gas for fertilizers, diesel for shipping, and field operations, and coal for dehydrating the ethanol, (natural gas is too expensive). When these are factored in ethanol dose little, or even increases GHGs.
Sorry Tse, I forgot to give a cite for my above comment. http://www.sciencemag.org/cgi/content/full/311/5760/506 They give GHGs of .85 to 1.06 of petroleum depending on distillation source.
Production of alternative fuels is very important, but we also have to understand the conditions of so many poor people around the globe who go to bed without a meal. Diverting corns to produce ethanol at early stages is OK. However we have to encourage the technology of producing biofuels using cellulose like materials which is not a feed of human beings. The initiatives of many American scientists can save this planet from green houses gases, fuel crisis etc.
I think we are off to a relatively good start on the idea of developing alternative fuel sources. The use of ethanol (from whatever source you wish to start with)is just the first step. This will give us time to work on other fuel sources including hydrogen fuel cells derived from spinach and cyanobacteria. The change from fossil fuels to alternative fuels will be gradual at best, but no one argues it is necessary. Only time and money will give us sustainable options.