reformer to generate hydrogen - rich gas, a power section where the electrochemical process occurs and a power conditioner to convert the direct current (DC) generated in the fuel celi into alternating current (AC). Fuel reforming ' frees ' the hydrogen in the fuel and removes other contaminants that would otherwise poison the catalytic electrodes. Fuel processing is usually performed at the point of use eliminating storage of the hydrogen -rich mixtures. Depending on the operating temperature of the fuel celi, fuel reforming is external or internal. DOE is currently funding a first of its kind 250 kW solid oxide fuel celi - MTG hybrid, which is an ideal size for a power park application. Pem fuel cells Proton exchange membrane fuel cells operate on hydrogen and hydrogen - rich gases and are being commercialized at module sizes varying from 3 to 7 kW, 50 kW and 250 kW to provide both power and heat for single family, planned residential and industrial developments. PEMFCs are being manufactured by several companies and several smali PEMFC systems wili be commercial within a year or so. Growing peak power demands and the impact of utility deregulation have decreased the reliability of the electric supply system to the point where fuel cells that can provide heat as weli as electricity at the site are becoming an competitive option. As such, there is significant industry interest in the development and the commercialization of these units which are directly applicable to the power park concept. in additon, since it is during peak power periods that the public experiences power outages and roliing brown outs, energy storage is an important element in assuring reliable power. Reversible fuel celis that can take electiricty generated during low - demand periods to electrolyze and store constituents that can be recombined in the fuel celi during peak periods to generate electricity can add to the energy park's cabability as areliable peak energy provider. Finaliy, the co - production of electricity and hyrogen can add the capability of providing fuel for hydrogen fuel celi vehicles and provide additional premium power back - up capacity for peak periods. Non - electric chillers This technology avoids the use fo peak electric power and is therefore idealiy suited for power parks. Absorption chillers, for instance, can use waste heat from CHP systems to produce chilied water. This aplication makes it possible to shift an electricity load to a thermal load, aliowing or continuing use of CHP systems during the cooling season. Recent developments in the double and triple -effect absoption chiliers have dramaticaliy improved their cost. Engine - driven chiliers operate compressors directly for refrigeration with aturbine or reciprocating engine. Heat is also recovered from the 4 81 ECOGENERATION WORLD engine in a boiler. This method is more efficient than using an electric motor because it limits the losses associated with generating electricity and then producing shaft power for the compressor. Recent improvements in sensors and controls have enabled lower - cost, smaller, packaged systems. DOE non - electric ehiller power park related projects include the DOE2s Building CHP ( BCHP ) all - gas building at the University of Maryland. District energy systems trict energy is another key power park strategy especially in combination with CHP. District energy systems distribute steam, hot water, and / or chilled water from a central plant to individual buildings through a network of pipes. District energy systems provide space heating, air conditioning, domestic hot water, and industrial process heat. They can use a variety of heat sources, including waste energy from CHP systems, industrial waste heat, geothermal heat, or deep lake water (for cooling). Steam Turbines Turbines are one of the most versatile and oldest prime mover technologies used to drive a generator or mechanical machinery. This generation technology produces more than 80% of US electricity. A steam turbine does not directly convert a fuel source to electric energy but requires a source of high - peressure steam. The steam is usualiy produced in a boiler or heat recovery steam generator. Boiler fuels such as coal, oil and natural gas or renewable fuels such as wood or municipal waste or geothermal energy. Steam turbines are also widely used for CHP applications in the US and Europe. Because of their relatively low electric to thermal ratios at the smalier power park type sizes, steam turbines would mainly be used with a district energy and / or a heat powered cooling system in a power park. An innovative power park aplication for steam tırbines is as a replacement for presure - reducing values in a district heating loop. This application is generally quite small scale, ie less than 1 MW. Manufacturers have lowered costs dramiticaliy on such modular, load - following, back pressure, steam turbine generators. SUMMARY Power parks, as an integrated ' systems approach ' to delivering power when and where it is needed, are expected to play an integral role in a restructured energy merketpalace in the US. Customers will demand solutions besed on power quality and reliability. DER technologies are cleaner, more efficient, more environmentally sound and, as deployed in power parks, can improve our energy management opportunities in both the near and long - term. As other parts of the world have come to realize, on-site power generation works. Source: Cogeneration and On-Site Power Production
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