Electric power cogeneration

Alternatively, short-rotation hybrid poplar and selected grasses can be multicropped on an energy plantation in the U.S. Northwest and harvested for conversion to Hquid transportation fuels and cogenerated power for on-site use in a centrally located conversion plant. The salable products are Hquid biofuels and surplus steam and electric power. This type of design may be especially useful for larger land-based systems. 

Thus, a cogeneration system is designed from one of two perspectives it may Be sized to meet the process heat and other steam needs of a plant or community of industrial and institutional users, so that the electric power is treated as a by-produc t which must be either used on site or sold or it may be sized to meet electric power demand, and the rejected heat used to supply needs at or near the site. The latter approach is the likely one if a utility owns the system the former if a chemical plant is the owner. 

Industrial use of cogeneration leads to small, dispersed electric-power-generation installations—an alternative to complete reliance on large central power plants. Because of the relatively snort distances over which thermal energy can be transported, process-heat generation is characteristically an on-site process, with or without cogeneration. 

Cogeneration systems will not match the varying power and heat demands at all times for most applications. Thus, an industrial cogeneration systems output frequently must be supplemented by the separate on-site generation of heat or the purchase of utility-supplied elec tric power. If the on-site electric power demand is relatively low, an alternative option is to match the cogeneration system to the heat load and contract for the sale of excess electricity to the local utihty grid. 

An explosion and fire (March 13, 1991) occurred at an ethylene oxide unit at Union Carbide Chemicals Plastics Co. s Seadrift plant in Port Lavaca, TX, 125 miles southwest of Houston. The blast killed one, injured 19, and idled the facility, that also produces ethylene, ethylene glycol, glycol ether ethanolamines, and polyethylene. Twenty-five residents were evacuated for several hours as a safety precaution. The plant lost all electrical power, for a few days, because its cogeneration unit was damaged. The Seadrift plant, with 1,600 workers, is capable of making 820 million lb per year of ethylene oxide which is one-third of Carbide s worldwide production of antifreeze, polyester fibers, and surfactants Seadrift produces two thirds of Carbide s worldwide production of polyethylene. 

The United States obtained about 9 percent of its electricity from combined heat and power (cogeneration) systems as of 1997. Cogeneration is more prevalent in some European nations than in the... 

See also Cogeneration Technologies Edison, Thomas Alva Electricity Electric Motor Systems Electric Power Transmission and Distribution Systems Matter and Energy Regulation and Rates for Electricity Siemens, Ernst Werner von Tesla, Nikola Thomson, Joseph John Townes, Charles Liard Turbines, Gas Turbines, Steam Volta, Alessadro Wlieatstone, Charles. 

Gas turbines can be fueled by either gas or liquid hydrocarbons. The gas turbine is often used as a means of utilizing what would otherwise be waste hydrocarbons gases and liquids to generate local electric power via the gas turbine power unit. This is called cogeneration. 

Utility plants primarily employ reheat condensing turbines, whereas cogeneration plants and larger process industries that produce their own electrical power tend to employ extraction turbines. Both types of turbine rely on a surface condenser to receive exhaust steam from the LP turbine stage and condense it to liquid for reuse. 

Boilers may be used for domestic hot water heating, space heating, waste heat, or chemical recovery. They also may be used for mechanical work, electrical power generation, cogeneration, and innumerable industrial process applications using direct (live) steam or indirect steam (e.g., coil heated) processes. Both FT and WT designs are commonly employed for heat-recovery applications. 

Designs often include boilers with economizers and pendant superheaters because many of the largest manufacturing operations require additional mechanical or electrical power to process steam and use combination heating and power services (cogeneration). 

Wagner was first to propose the use of solid electrolytes to measure in situ the thermodynamic activity of oxygen on metal catalysts.17 This led to the technique of solid electrolyte potentiometry.18 Huggins, Mason and Giir were the first to use solid electrolyte cells to carry out electrocatalytic reactions such as NO decomposition.19,20 The use of solid electrolyte cells for chemical cogeneration , that is, for the simultaneous production of electrical power and industrial chemicals, was first demonstrated in 1980.21 The first non-Faradaic enhancement in heterogeneous catalysis was reported in 1981 for the case of ethylene epoxidation on Ag electrodes,2 3 but it was only... 

In recent years it was shown that solid electrolyte fuel cells with appropriate electrocatalytic anodes can be used for chemical cogeneration i.e. for the simultaneous production of electrical power and useful chemicals. 

The spurred impetus has been given to developing non pollutant vehicles, and consequently, the clean cars driven by the fuel cells loading proton exchange membranes (PEMFC), which based upon Nafion, have been surprisingly developed. A promising less pollutant and economical system is also expected, which will be the on site cogeneration system of electric power and the hot water supply with use of fuel cells combined with city gas pipe-lines. 

In some European cities, waste heat from fossil fuel electric power plants is used for district heating with an overall energy efficiency of 85%. These plants were not originally constructed as cogenerating units. Waste heat from industrial process plants can also be used. Geothermal sources are used to provide heat for district heating systems in Iceland and Boise, Idaho. 

The U.S. Department of Energy (DOE) has started the billion- dollar, FutureGen project to demonstrate a 275-megawatt prototype plant that cogenerates electric power and hydrogen and sequesters 90% of the C02. 

The major applications for fuel cells are as stationary electric power plants, including cogeneration units as motive power for vehicles and as on-board electric power for space vehicles or other closed environments. Derivative applications will be summarized. 

Cogeneration (supply both electrical power and heat)... 

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