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Digesting the problem
Terry Slavin, The Guardian
Looking at the cows on his dairy farm in Devon, Winston Reed does not see what many environmentalists do: animals burping up vast quantities of methane, a greenhouse gas 21 times more potent than CO2. He is more concerned with what comes out of the animals’ other end – and it offers hope for the planet. As Reed says: “The poo from four cows can produce enough energy to heat and light a house for a year.”
Unlike the methane that cows and other ruminants exhale as their stomachs convert grass into milk, and which is believed to be responsible for up to a quarter of “manmade” methane emissions worldwide, the gas in their manure can be harnessed as a force for good. And the same goes for all other forms of organic waste that would otherwise rot in landfill sites.
Reed, 35, is seeking planning permission to build an energy centre on his farm, in a rural community on the outskirts of Tiverton, near Exeter, taking in manure from local farms and waste from local abattoirs and food processors. It would not be the first of its kind in the UK, but it would be by far the most ambitious – creating electricity to light 6,000 local houses and £700,000 worth of heat for local industries, including a sawmill plant making wood pellets for biomass boilers. Since Tiverton’s population is only 20,000, it will go a long way to making the town self-sufficient in energy, he says…
(30 July 2008)
Using crop residue for biofuels hurts soil quality (podcast)
Karen Hopkin, Scientific American
Biofuels sound like such a good idea. A clean-burning fuel that reduces our need for foreign oil. What’s not to like? Well, for one thing, turning corn into biodiesel could be taking food off hungry people’s plates. “Okay,” biofuel advocates say, “suppose we just use the stems and leaves that are left over after crops are harvested? That should solve the problem.” Well, maybe not entirely. Because removing that so-called crop residue takes food away from soil microbes. They convert that material into the nutrients that crops need. So says USDA scientist Ann Kennedy of Washington State University.
Microbes break down crop residue to form organic matter—the stuff that gives soil its rich, dark color. Organic matter, in turn, provides nutrients, helps the soil retain water, and prevents erosion. So, if you harvest the crop residue to produce biofuels, you remove the materials that are fodder for the bugs that make organic matter. Soil quality would drop, and farmers would have to find some other way to fertilize their fields. So biofuels are not a magic bullet. Maybe you should just eat the corn and ride your bike…
(30 July 2008)
Obama’s biofuels policy tension
US presidential hopeful Barack Obama is coming under increasing pressure to change his policies on biofuels.
Senator Obama has been a big supporter of corn subsidies for American farmers to produce the plant-fuel ethanol.
But a new report from his own green adviser warns of the many problems associated with the biofuel.
Daniel Kammen’s paper says that a car will emit more greenhouse gases driving on corn ethanol processed with coal than it will using normal petrol…
(28 July 2008)