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Encyclopedia > Distributed generation

Distributed generation generates electricity from many small energy sources. It has also been called also called on-site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy. Lightning strikes during a night-time thunderstorm. ...


Currently, industrial countries generate more than 99% of their electricity in large power plants, the majority of which burn coal.[citation needed] Some countries also use efficient generators burning natural gas, nuclear reactors or hydropower. A power station (also power plant) is a facility for the generation of electric power. ... Coal Coal (IPA: ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine, this last step enhances the efficiency of electricity generation. ... Core of a small nuclear reactor used for research. ... Undershot water wheels on the Orontes River in Hama, Syria Saint Anthony Falls Hydropower is the capture of the energy of moving water for some useful purpose. ...


These plants have excellent economies of scale, but usually transmit electricity long distances. Coal plants do so to prevent pollution of the cities. Nuclear reactors are thought too unsafe to be in a city. Dam sites are often both unsafe, and intentionally far from cities. The coal and nuclear plants are too far away for their waste heat to be used for heating buildings.


Low pollution is a crucial advantage of combined cycle plants that burn natural gas or that gasify coal. The low pollution permits the plants to be near enough to a city to be used for district heating and cooling. In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine, this last step enhances the efficiency of electricity generation. ... Natural gas is a gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, butane, propane, carbon dioxide, nitrogen, helium and hydrogen sulfide. ... Coal Coal (IPA: ) is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... District heating pipe in Tübingen, Germany District heating (less commonly called teleheating) is a system for distributing heat generated in a centralized location for residential and commercial heating requirements. ...


So-called inherently safe nuclear reactors such as the pebble bed reactors and molten salt reactors have no proven safety advantage: They are unlikely to be safe enough to be deployed near cities, nor to be used for process waste heat generation either. Core of a small nuclear reactor used for research. ... Graphite Pebble for Reactor The pebble bed reactor (PBR) or pebble bed modular reactor (PBMR) is an advanced nuclear reactor design. ... A molten salt reactor is a type of nuclear reactor where the working fluid is a molten salt. ...


Distributed generation is another approach. It reduces the amount of energy lost in transmitting electricity because the electricity is generated very near where it is used, perhaps even in the same building. This also reduces the size and number of power lines that must be constructed.


Typical distributed power sources have low maintenance, low pollution and high efficiencies. In the past, these traits required dedicated operating engineers, and large, complex plants to pay their salaries and reduce pollution. However, modern embedded systems can provide these traits with automated operation and clean fuels, such as sunlight, wind and natural gas. This reduces the size of power plant that can show a profit. A router, an example of an embedded system. ... Natural gas is a gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, butane, propane, carbon dioxide, nitrogen, helium and hydrogen sulfide. ...


The usual problem with distributed generators are their high costs.


The one exception is probably microhydropower. A well-designed plant has nearly zero maintenance costs, and generates useful power indefinitely. Micro Hydro is a term used for hydroelectric power installations that typically produce up to 100 kW of power. ...


One favored source is solar panels on the roofs of buildings. These have high construction costs ($2.50/w, 2007). This is about fifty-fold higher than coal power plants ($0.047/w, 2007) and 40-fold higher than nuclear plants ($0.06/w, 2007). Most solar cells also have waste disposal issues, since solar cells often contain heavy-metal electronic wastes. The plus side is that unlike coal and hydropower, there are no pollution, mining safety or operating safety issues. A photovoltaic module is composed of individual PV cells. ...


Another favored source is small wind turbines. These have low maintenance, and low pollution. Construction costs and total safety are also manyfold ($0.80/w, 2007) less per watt than large power plants, except in very windy areas. Wind towers and generators have substantial insurable liabilities caused by high winds, but good operating safety. A tall tower holds a wind turbine aloft where winds are consistently stronger. ...


Distributed cogeneration sources use natural gas-fired microturbines or reciprocating engines to turn generators. The hot exhaust is then used for space or water heating, or to drive an absorptive chiller for air-conditioning. The clean fuel has only low pollution. Designs currently have uneven reliability, with some makes having excellent maintenance costs, and others being unacceptable. Cogeneration (also combined heat and power or CHP) is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat. ... Natural gas is a gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, butane, propane, carbon dioxide, nitrogen, helium and hydrogen sulfide. ... This machine has a single-stage radial compressor and turbine, a recuperator, and foil bearings. ... Components of a typical, four stroke cycle, DOHC piston engine. ... This article needs to be wikified. ... In the broadest sense air conditioning can refer to any form of cooling, heating, ventilation or disinfection that modifies the condition of air, typically for thermal comfort. ...


Cogenerators are also more expensive per watt than central generators. They find favor because most buildings already burn fuels, and the cogeneration can extract more value from the fuel.


Some larger installations utilize combined cycle generation. Usually this consists of a gas turbine whose exhaust boils water for a steam turbine in a Rankine cycle. The condenser of the steam cycle provides the heat for space heating or an absorptive chiller. Combined cycle plants with cogeneration have the highest known thermal efficiencies, often exceeding 85%. In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator generates electricity and the waste heat from the gas turbine is used to make steam to generate additional electricity via a steam turbine, this last step enhances the efficiency of electricity generation. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... The Rankine cycle is a thermodynamic cycle. ...


See also

Energy Portal

Image File history File links Portal. ... It has been suggested that this article or section be merged with Off-the-grid. ... Cogeneration (also combined heat and power or CHP) is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat. ... Power line redirects here. ... For delivered electrical power, see Electrical power industry. ... “Dynamo” redirects here. ... 11kV/400V-230V transformer in an older suburb of Wellington, New Zealand Electricity distribution is the penultimate stage in the delivery (before retail) of electricity to end users. ... Electricity generation is the first process in the delivery of electricity to consumers. ... An electricity market is a system for effecting the purchase and sale of electricity using supply and demand to set the price. ... Electricity retailing is the final process in the delivery of electricity from generation to the consumer. ... Energy demand management is also known as demand side management (DSM). ... It has been suggested that this article or section be merged into energy development. ... Micro Combined Heat and Power or MicroCHP is an extension of the now well established idea of Cogeneration to the single/multi family home or small office building. ... It has been suggested that Wind turbines (UK domestic) be merged into this article or section. ... This machine has a single-stage radial compressor and turbine, a recuperator, and foil bearings. ... Net metering is a state level electricity policy for consumers who own qualifying facilities, which are generally smaller, renewable energy sources such as a wind or solar power. ... World renewable energy in 2005 (except 2004 data for items marked* or **). Enlarge image to read exclusions. ... Solar Guerrilla (or the guerrilla solar movement) is a term given to a person who uses an alternative energy source such to illegally supply electricity back to the public utility grid[1] Off grid renewable energy systems typically equire expensive battery systems, however with a simple inverter, energy from solar... A sustainable community energy system is an integrated approach to supplying a local community with its energy requirements from renewable energy or high-efficiency co-generation energy sources. ... Trigeneration implies the simultaneous production of mechanical power (often converted to electricity), heat and cooling from a single heat source such as solar energy or fuel. ... A virtual power plant is a cluster of distributed generation installations (such as microCHP, wind-turbines, hydrogen stations, back-up gensets etc. ...

External links


  Results from FactBites:
 
UCI scientists first to predict air quality impact of small-scale power sources (1037 words)
Distributed generation should be installed equally throughout the air basin, not concentrated in any one area, and the cleanest generation technologies such as fuel cell and photovoltaic devices should be used.
If fuel cells alone were used in place of a mixture of distributed generation technology investigated by the research team, they could lead to a reduction of up to three parts per billion in peak ozone and up to two micrograms per cubic meter of peak particulate matter, researchers said.
Their findings suggest that fuel cell distributed generation could reduce future peak ozone concentrations by as much as six parts per billion and peak particulate matter by up to three micrograms per cubic meter compared to current power plant technology.
Modeling Distributed Electricity Generation in the NEMS Buildings Models (5851 words)
Although the emerging distributed generation technologies (PV, fuel cells and microturbines) exhibit cost declines throughout the projection period, the cost declines are not large enough to spur significant projected gains in penetration over the next 20 years under the reference case conditions.
Total distributed generation in the buildings sector is projected to increase by 56 trillion Btu from the reference case in 2020, with most of the increase occurring after 2010.
Distributed generation technologies, particularly fuel cells and PV, have received a great deal of attention from the energy community regarding their potential to save energy, increase the reliability of electricity supply, and decrease the cost of extending the current electrical grid.
  More results at FactBites »


 

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