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CHARACTERISTICS In the process of electricity generation, only a portion of the available energy can be converted into useful energy. A significant portion of the heat energy available in the combustion of fuel is wasted, as demonstrated by operating efficiencies in the range of 34%; today's most efficient combined-cycle systems have average efficiencies in the low 50% range. The largest source of waste heat is the warm water produced by steam condensation. This waste heat can be used for process steam, hot water heating, space heating, and other thermal needs. If the energy content is sufficiently high, the steam could also be used to generate additional electricity in a cogeneration (or combined heat and power) system. Current water heating system design methods focus on meeting hot water needs and generally ignore energy consumption, operating costs, and other effects. As a result, utility customers often fail to make informed decisions and consequently sacrifice potential savings and benefits. It is possible to funnel this steam through a steam turbine to cogenerate electricity. Doing so can improve the efficiency of the system to as much as 80 or 85%. Using the heat from this source to generate electricity could displace fossil fuel consumption, thereby avoiding the emission of greenhouse gases. Hot flue gases from boilers can provide a source of waste heat for a variety of uses. The most common use is for pre-heating boiler feed water. Heat exchangers used in flues must be constructed to withstand the highly corrosive nature of cooled flue gases. SIZE: FEATURES: COST: CURRENT USAGE: POTENTIAL USAGE: ISSUES ASSOCIATED WITH IMPLEMENTING ACTION
CLIMATE CHANGE IMPACT EMISSION EFFECT:
EMISSION ESTIMATE: COST-EFFECTIVENESS: SECONDARY EFFECTS: RESOURCES
CONTACTS Energy Efficiency and Renewable Energy Clearinghouse (EREC) Electric Power Research Institute 3The City of Renville, Minnesota has implemented a waste heat recovery system in which an effluent hot waste stream (6,000 gallons of water/minute @ 90-120º F) is pumped to one of two hot water heat exchangers. The heat from the hot waste stream is captured by a heat exchanger; the cooled waste stream is returned to a plant for further cooling and treatment. The captured heat is transferred to water in a closed loop that travels 4,000 feet to the industrial user, in this case, a fishery (other users may include greenhouse or hydroponic farming, e.g.). After the heat is extracted for use, the water in the closed loop is reheated and recirculated. The present system of four pumps and two heat exchangers can be doubled. As presently configured, the project provides 35 million Btu's from 2,000 gallons per minute of hot water circulating through a 24-inch diameter pipe system. Total cost of reconfiguration was approximately $657,000, part of The City of Renville, Minnesota has implemented a waste heat recovery system in which an effluent hot waste stream (6,000 gallons of water/minute @ 90-120º F) is pumped to one of two hot water heat exchangers. The heat from the hot waste stream is captured by a heat exchanger; the cooled waste stream is returned to a plant for further cooling and treatment. The captured heat is transferred to water in a closed loop that travels 4,000 feet to the industrial user, in this case, a fishery (other users may include greenhouse or hydroponic farming, e.g.). After the heat is extracted for use, the water in the closed loop is reheated and recirculated. The present system of four pumps and two heat exchangers can be doubled. As presently configured, the project provides 35 million Btu's from 2,000 gallons per minute of hot water circulating through a 24-inch diameter pipe system. Total cost of reconfiguration was approximately $657,000, part of which will be repaid by industrial park user fees. http://www.bolton-menk.com | ||||||||
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