Burning trash and keeping the car clean: what do you think of those "waste-to-energy" plants used by cities to generate power?
Waste-to-energy (WtE) facilities, which generate power by burning trash, have been in widespread operation in the U.S. and Europe since the 1970s and are considered by environmental advocates to be a mixed blessing. They get rid of garbage without adding to already stressed landfills and with the added benefit of contributing electricity to the power grid. But they also generate pollution, usually as a result of burning vinyl and plastics. WtE facilities evolved out of basic incinerator technology that simply burns trash and reduces it to ash and smoke. Waste-to-energy plants instead use the garbage to fire a huge boiler. When the garbage "fuel" is burned, it releases heat that turns water into steam. The high-pressure steam turns the blades of a turbine generator to produce electricity.
In the U.S. and Europe, environmental laws regulate WtE plants, typically requiring them to use various antipollution devices to keep both harmful gases and particulate pollution (fine bits of dust, soot and other solid materials) out of the air. However, the particles captured are then mixed with the ash that is removed from the plant's furnace when it is cleaned. Environmentalists contend that this toxic ash may actually present more of an environmental problem than the airborne emissions themselves, as it usually ends up in landfills where it can leak into and contaminate soil and groundwater.
According to Greenpeace International, WtE facilities are also among the largest sources of dioxin emissions in industrialized countries. Dioxin is a byproduct of burning polyvinyl chloride (PVC) and other plastics, and has been linked to cancer and other health problems.
Greenpeace advocates phasing out WtE facilities in favor of improving recycling rates that reduce the waste stream in the first place. Currently about 600 WtE facilities are in operation around the world; the U.S. is home to 98, which manage about 13 percent of America's total trash output. CONTACT: National Solid Wastes Management Association, www.nswma, org; Greenpeace Incineration Campaign, www.greenpeace.org/international/campaigns/toxics/incin eration.
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|Title Annotation:||EARTH TALK: Questions & Answers About Our Environment|
|Date:||Jan 1, 2007|
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