Dear EarthTalk: 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 1970sand are considered by environmental advocates to be a mixed blessing. On the one hand, they get rid of garbage without adding to already-stressed landfills and with the added benefit of contributing electricity to the power grid. On the other hand, they do generate toxic 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 anti-pollution 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 bottom of the waste-to-energy plant’s furnace when it is cleaned. Environmentalists contend that this toxic ash, which can include dangerous heavy metals, 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 by-product of burning polyvinyl chloride (PVC) and other plastics, and has been linked to cancer and other health problems. Greenpeace advocates for 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. According to the National Solid Wastes Management Association, an industry trade group, the United States is home to 98 such plants operating in 29 states. These facilities manage about 13 percent of America’s total trash output. In Canada, where landfill space is more abundant, WtE has failed to catch on, with only a few such facilities across the country. WtE has caught on more so in smaller technologically advanced countries such as Japan, Sweden, Denmark, France and Switzerland, where landfill space is at a premium.

Recent improvements in the energy efficiency and environmental impact of WtE facilities means that the technology promises to play a larger role globally in years to come, especially as crowded developing countries start to jump on the bandwagon.



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