| Waste-to-energy Plant |
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Sweden has been a leader in waste-to-energy production over the past 20 years, with considerable advances in efficiency of waste-to-energy conversion rates, and reduced emissions. Other countries are increasingly looking at waste-to-energy as a potential energy diversification strategy, and to address growing landfill problems. Modern waste-to-energy plants should not be confused with the trash Incinerator s that were commonly used until a few decades ago. Those plants usually did not remove hazardous or recyclable materials before burning. In fact, the process used was not that much different from burning trash in a pit or barrel. The old incinerators endangered the health of the plant workers and the nearby residents. Also, most of these incinerators did not generate electricity. Waste-to-energy plants share much of their design and equipment with other steam-electric power plants, particularly Biomass plants. First, waste is brought to the facility. Then, the waste is sorted to remove recycleable and hazardous materials. The waste is then stored until it is time for burning. The waste can be added to the Boiler continuously or in batches, depending on the design of the plant. Modern waste-to-energy plants are designed to reduce the formation of new pollutants in the furnace, such as Nitrogen Oxides , Sulfur Oxides and Particulates , and to destroy pollutants already present in the trash. Pollution control measures, such as Baghouse s, Scrubber s and Electrostatic Precipitator s capture most of the pollution not destroyed by combustion. Odor pollution can be a problem when the plant location is not isolated. Some plants store the waste in an enclosed area with a negative pressure, which prevents unpleasant odors from escaping, and the air drawn from the storage area is sent through the boiler or a filter. Unfortunately, not all plants are operated in the best possible manner and the concerns and complaints of nearby residents are often legitimate. Another issue that affects community relationships is the increased road traffic of garbage trucks to bring municipal waste to the waste-to-energy facility; due to this reason, most waste-to-energy plants are located in industrial areas. Fuel cost for a typical coal or natural gas plant can account for as much as 45% of the cost to produce electricity in a coal-powered plant, and 75% or more in a natural gas-powered plant. Waste-to-energy plants may have a significant cost advantage over traditional power options in some countries, as the waste-to-energy operator may receive revenue (versus having to pay for the cost of fuel) for receiving waste as an alternative to the cost of disposing of waste in a landfill. This revenue is typically referred to as a "tipping fee". This term refers to the cost to "tip" a garbage filled truck at a landfill, and is typically defined on a "tipping fee" per ton basis. For example, the National Solid Waste Management Association (www.nswma.org) estimates that the average United States tipping fee for 2002 was $33.70 per ton. A modern, properly run waste-to-energy plant sorts material before burning it and can co-exist with Recycling . In fact, recycling rates are typically higher in areas that have waste-to-energy plants. Items that are not recyclable, by design or economically, and are not hazardous can be sent to the plant for burning. In addition, the plants allow the previously unrecycleable Metal s integrated into products to be captured. The metals are collected from the bottom of the Furnace and sold to Foundries . There is always some level of Pollution generated at power plants. Waste-to-energy plants emit more pollution than Natural Gas plants, but less than Coal plants, which produce half of the electricity in the United States. A few plants use Gasification , which is thought to be less polluting, perhaps incorrectly, but most combust the waste directly because it is a mature, efficient technology. Waste-to-energy plants also reduce the volume of waste by 80 to 90%. Sometimes the ash is clean enough to be used for some purposes such as raw materials for use in manufacturing cinder blocks or for road construction, but otherwise it is landfilled. However, depending on the design of the plant, its level of sosphistication in emissions control, the temperature in which waste is burned, and the type of waste being burned, the plant may produce significantly more pollution and the ash and other wastes may be highly toxic. High temperature, efficient combustion, and effective emissions scrubbing and controls can significantly reduce pollution outputs, potentially below coal-fired plant emission levels. Burning waste does produce Dioxin , as do coal and natural gas plants. How much dioxin is greatly debated. Advances in emission control design and new regulations have caused large reductions in the amount of pollution produced by waste-to-energy plants, particularly dioxin. However, it produces more dioxin than other fuels, such as natural gas. Also, Solar , Wind and Hydroelectric power do not produce dioxin at all. Others believe that the amount of pollution produced is offset by the landfill space saved, emissions and greenhouse warming concerns of burning landfill gases, reduced mining and drilling, increased metal captured, pollutants destroyed in the furnace, and the electricity produced, which might have otherwise been produced at a traditional coal fired electrical plant which account for the majority of electrical production in many countries. Landfill gas, which contains about 50% Methane , and 50% Carbon Dioxide , is contaminated with a small amount of pollutants. Unlike at waste-to-energy plants, there are little or no pollution controls on the burning of Landfill Gas , which is usually flared or used to run a Reciprocating Engine or Microturbine . Cleaning up the landfill gas is usually not cost effective because Natural Gas , which it substitutes for, is relatively cheap. However, it might be a better solution to regulate the burning of landfill gas than to use waste-to-energy plants. |
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