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Plasma arc gasification is a waste treatment technology that uses high electrical energy and high temperature created by an Electrical Arc Gasifier . This arc breaks down waste primarily into elemental gas and solid waste (slag), in a device called a '''plasma converter'''. The process has been intended to be a net generator of electricity, depending upon compostition input wastes, and to reduce the volumes of waste to being sent to Landfill sites. PRINCIPLE OF OPERATION Relatively high voltage, high amperage electricity is passed between two electrodes, spaced apart, creating an electrical arc. Inert gas (air or inert gases under pressure) is passed through the arc into a sealed containment containing waste material, temperatures as high as 13,000°C (25,000°F) are reached in the arc. The temperature one meter from the arc can be as high as ~4000°C (~8,000°F). At these temperatures most types of waste are broken into basic elemental components in a gaseous form, and Complex Molecules are Atomized - separated into individual atoms. The reactor operates at a slightly Negative Pressure , meaning that the feed system is complemented by a gaseous removal system, and later a solid removal system. Depending on the input waste ( Plastics tend to be high in Hydrogen and Carbon ), gas from the plasma containment can be removed as Syngas , and may be refined into various fuels at a later stage. LOCATIONS The first plasma based waste disposal system in the USA is scheduled to come into operation in ) of solid rubble from around 3000 tons (2.7 million kg) of waste per day at around 5500°C. The city of Tallahassee, Florida has signed the largest plasma arc waste to energy contract (35MW) to date with Green Power Systems to process 1,000 tons daily from the city and several surrounding counties. Completion of the project is scheduled for October 2010. Three similar but smaller plants are in operation in Japan -- a 166 ton/day "pilot" plant in Yoshii, co-developed by Hitachi Metals Ltd. and Westinghouse Plasma , which was certified after a demonstration period in 1999-2000; a 165 ton/day plant in Utashinai City, completed in 2002; and a 28 ton/day plant commissioned by the twin cities of Mihama and Mikata in 2002 {Link without Title} . An unknown source has stated that at least one of the plants in Japan has not managed to produce more energy than it consumes. Two similar facilities run by different companies in Australia and Germany closed after failing to meet emissions standards. EnviroParks Limited [http://www.letsrecycle.com/do/ecco.py/view_item?listid=37&listcatid=217&listitemid=9136 plan (31/9/07) a consortium to build an Organic Park in Tower Colliery at Hirwaun, South Wales. This includes ''' Plasco Energy Group Inc ''', plasma gasification plant with Northern Irish anaerobic digestion specialists '''B9 Organic Energy''', US-owned agricultural waste specialists '''Agritec Systems Ltd''' and York-based oil processing specialists '''Ebortec Ltd''', as well as Austrian firm Biodiesel '''Technologies GmbH'''. This could eliminate the need for future incinerators (EfW facilities) to divert Municipal Solid Waste from Landfill. As much as £60 million is being put into the project by EnviroParks Ltd and its partners, to establish organic waste and mixed waste treatment facilities next to the Tower Colliery at Hirwaun. The Hirwaun site itself is large enough for the processing of over 250,000 tonnes of non-hazardous waste a year. Initially, though, an anaerobic digestion plant will be designed to handle 50,000 tonnes of organic wastes a year, with the potential for a 100% expansion. Advanced Plasma Power [http://www.advancedplasmapower.com/ have built a plasma gasification modular test facility in Farringdon, Oxfordshire, England that uses Refuse Derived Fuel RDF feedstock to produce hydrogen, syngas, energy and vitrified gravel. CONCERNS Dioxin emissions are possible from plasma arcs when Chlorine is present. Process gas cleanup is necessary when gasifying waste streams such as municipal waste streams known to contain heavy metals, chlorine/fluorine, sulfur, etc. In 2004, the city of Honolulu considered a plasma arc/torch proposal for processing municipal solid waste. The city's Department of Environmental Services evaluated the plasma process and found that using plasma arc/torch technology would significantly boost waste disposal costs without offering worthwhile environmental advantages. {Link without Title} City of Honolulu press release, March 30, 2004: City to Brief Council on Plasma Arc Recommendations for Landfill. It is important to note, that at this stage, no municipal-waste disposal sized plasma arc facilities have as yet been constructed, and therefore they pose a considerable technological and budgetary challenge to even the largest municipalities. While some believe Federal funding is required to make better progress on this means of waste disposal (which is scientifically not the same principle as waste incineration), others note that basic thermodynamics show electricity costs to be unavoidably high when processing wet wastes such as municipal wastes. The technology of using plasma arc to treat waste has not changed significantly in principle from initial concept inception. Practical (limited use of land space for land-fills), technological (large-scale use of technology versus small-scale, e.g. plasma arc is currently favoured as a means to destroy medical and hazardous waste), logistical (transportation infrastructure requirements) and budgetary considerations all affect the viability of individual projects. Plasco Energy Group Inc. is nearing completion in approx. March 2007 of a plasma-arc waste demonstration plant in Ottawa, Canada at the Trail Road Landfill, for the specified use of 100 metric tonnes per day volume of waste. An issue regarding plasma systems is in the life of their liners. The liner is an important aspect of separating the high interior temperatures of the plasma system from the shell of the plasma container. Liners are highly susceptible to both chlorine attack and to local variabilities in [high temperatures, both of which would be found with typical municipal waste systems, and are not likely to last more than a year in service. REFERENCES SEE ALSO EXTERNAL LINKS
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