Soot From Wood Stoves Impacts Global Warming More Than Expected
Pastor Dale Morgan
Soot From Wood Stoves Impacts Global Warming More Than Expected*
Washington DC (SPX) Oct 25, 2006
New measurements of soot produced by traditional cook stoves used in
developing countries suggest that these stoves emit more harmful smoke
particles and could have a much greater impact on global climate change
than previously thought, according to a study scheduled to appear in the
Nov. 1 issue of the American Chemical Society journal Environmental
Science and Technology.
Perhaps as many as 400 million of these stoves, fueled by wood or crop
residue, are used daily for cooking and heating by more than 2 billion
people worldwide, according to the study's lead authors, Tami Bond,
Ph.D., and doctoral candidate Chris Roden of the University of Illinois,
Urbana-Champaign.
In a field test in Honduras, the researchers found that cook stoves
there, which are similar to those used in other developing nations,
produce two times more smoke particles than expected, based on previous
laboratory studies. These dark, sooty particles, which are darker than
those produced by grassland or forest fires, have a climate warming
effect because they absorb solar energy and heat the atmosphere,
according to Roden.
In earlier work, Bond estimated that burning firewood -- the principal
fuel for cook stoves in the developing world -- produces 800,000 metric
tons of soot worldwide each year. In comparison, diesel cars and trucks
generate about 890,000 metric tons of soot annually. These two sources
each account for about 10 percent of the soot emitted into the world's
atmosphere each year, she said.
In addition to its environmental effects, smoke from cook stove fires is
a major cause of respiratory problems, eye infections and tuberculosis,
according to the researchers.
"Emissions from wood cook stoves affect the health of users --
especially of women and children -- neighborhood air quality, and global
climate. Reducing these emissions, through the use of cleaner burning
stoves and fuels, should have far-reaching benefits," Bond said.
In the past, scientists have relied on laboratory measures of pollutants
from cooking fires because field tests have been difficult to conduct,
in part, because of limited access to remote locations and a lack of
power to operate the scientific equipment, according to Roden. To get a
more accurate measure of the environmental impact of these stoves, Roden
and Bond developed a portable battery-operated sampling cart, which
includes sensors for measuring carbon dioxide and carbon monoxide,
particle soot absorption, particle color and concentration, which they
took to Honduras for field tests.
Honduras is typical of Central American countries, where more than 80
percent of families cook their meals over open wood fires, according to
Trees, Water and People, an American nonprofit agency which, along with
the Honduran Association for Development, helped facilitate this study.
In most cases, these families can't afford or don't have access to
electricity, gas or alternative fuel sources.
"We expected field measurements to be different from lab measurements,
and we suspected the amount of black carbon from these stoves would be
higher than open burning, but we were surprised by how much," Roden said.
Trees, Water and People and other nonprofit agencies are distributing
new low-cost, wood-burning cook stoves in Honduras and other Latin
American countries that appear to be less polluting and more fuel
efficient, according to the researchers. However, further analysis is
needed.
"Designing and distributing improved cook stoves may be an effective
method of mitigating global climate change, and can improve the health
of the users," Roden said. "However, the cook stoves must be well
designed and properly tested. They must be built with local traditions
and practices in mind and must be easy to use, or they may become
expensive doorstops."