Jul 06 2010

Cooking Up an Assault on Global Warming

Posted by: Jonathan Marshall

While legions of engineers and scientists pursue high-tech breakthroughs in clean energy, a small investment in low-tech stoves might buy the world precious years in the fight against global warming.

That’s one message that can be drawn from a new study by two Princeton researchers published in the prestigious Proceedings of the National Academy of Sciences. They conclude that sooty particles--from sources of incomplete combustion such as diesel engines and inefficient coal burners--absorb radiation, warming the atmosphere and contributing to the rapid melting of snow and glaciers. Controlling such emissions would be a smart way to get a jump on climate change, they stress.

Their work lends powerful support to a study published in Nature Geoscience in 2008, which fingered black carbon as the second most potent source of global warming, behind only carbon dioxide. It blamed carbon soot for half the total increase in Arctic temperatures from 1890 to 2007.

One major source of black carbon is the burning of wood and cow dung for cooking by poor households in India, China and other parts of the developing world.

Inefficient burning has a host of health and environmental consequences in addition to global warming. According to UC Berkeley energy expert Daniel Kammen,

Half the world's population of nearly six billion people prepare their food and heat their homes with coal and the traditional biomass fuels of dung, crop residues, wood and charcoal. . . . In rural areas, women and children may spend several hours a day collecting wood for cooking or making charcoal, tasks that contribute to deforestation and soil erosion. Worse, the choking smoke from indoor wood fires causes respiratory disease--mainly pneumonia--which is the leading health hazard in developing nations and annually kills four to five million children worldwide.

Fortunately, international development organizations and NGOs are working to promote widespread adoption of more efficient stove designs to cut down on the use of fuel and, as a byproduct, reduce soot output.

Kammen notes that traditional open fires, used by millions of rural homes, direct only 10 percent of their heat to cooking. A metal stove may be at most twice as efficient. In contrast, a high-efficiency stove like the Kenya Ceramic Jiko, which adds an insulating liner, is up to 40 percent efficient—dramatically reducing fuel use and household costs. In mass production, the stove costs a mere $2.

Many efficient stove designs now exist, but one size doesn't fit all. Researchers at Lawrence Berkeley National Laboratory, who developed the noted Berkeley-Darfur Stove, discovered when asked to create a stove for Ethiopia that they had to modify their design for local conditions, depending on the type of fuel (wood, cow dung, etc.), the size and shape of cooking pots, and other regional factors.

Just as there’s no single solution for stove designs, so there’s no single solution for global warming. Attacking the problem will take high tech, low tech, marketing, sociology and even anthropology. But helping desperately poor people find healthier, cheaper and more environmentally benign ways to cook sounds like a great place to start.

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