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Micro combined heat and power
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Micro combined heat and power
Micro combined heat and power, micro-CHP, μCHP or mCHP is an extension of the idea of cogeneration to the single/multi family home or small office building in the range of up to 50 kW. Usual technologies for the production of heat and power in one common process are e.g. internal combustion engines, micro gas turbines, stirling engines or fuel cells.
Local generation has the potential for a higher efficiency than traditional grid-level generators since it lacks the 8-10% energy losses from transporting electricity over long distances. It also lacks the 10–15% energy losses from heat transport in heating networks due to the difference between the thermal energy carrier (hot water) and the colder external environment.
The most common systems use natural gas as their primary energy source and emit carbon dioxide; nevertheless the effective efficiency of CHP heat production is much higher than of a condensing boiler, and thus reducing emissions and fuel costs.
A micro-CHP system usually contains a small heat engine as a prime mover used to rotate a generator which provides electric power, while simultaneously utilizing the waste heat from the prime mover for an individual building's space heating and the provision of hot domestic water. With fuel cells there is no rotating machinery, but the fuel cell's stack and where applicable also the reformer will provide useful heat. The stack does generate DC power which is converted by DC/AC inverter into mains voltage. Micro-CHP is defined by the EU as less than 50 kW electrical power output, however, others have more restrictive definitions, all the way down to <5 kWe.
A micro-CHP generator may primarily follow heat demand, delivering electricity as the by-product, or may follow electrical demand to generate electricity, with heat as the by-product. When used primarily for heating, micro-CHP systems may generate more electricity than is instantaneously being demanded; the surplus is then fed into the grid.
The purpose of cogeneration is to make use of more of the chemical energy in the fuel. The reason for using CHP systems is that large thermal power plants which generate electric power by burning fuel produce between 40% and 60% low-temperature waste heat, due to Carnot's theorem. The temperature produced by this waste heat (around 80 °C - 150 °C) does allow it to be used for space heating purposes, therefore in some urban areas district heating networks have been installed. Heat networks have a limited extent, as it is not economical to transport heat long distances due to heat loss from the pipes, and it will not reach into areas of low population density, or else revenues per CAPEX will go down. Where no district heating is possible due to low heat demand density or because the local utility has not invested in costly heat networks, this thermal energy is usually wasted via cooling towers or discharged into rivers, lakes or the sea.
Micro CHP systems allow highly efficient cogeneration while using the waste heat even if the served heat load is rather low. This allows cogeneration to be used outside population centers, or even if there is no district heating network. It is efficient to generate the electricity near the place where the heat can also be used. Small power plants (μCHP) are located in individual buildings, where the heat can be used to support the heating system and recharge the hot domestic water tank, thus saving heating oil or heating gas. CHP systems are able to increase the total energy utilization of primary energy sources. Thus CHP has been steadily gaining popularity in all sectors of the energy economy, due to the increased costs of electricity and fuel, particularly fossil fuels, and due to environmental concerns, particularly climate change.
In a traditional power plant delivering electricity to consumers, about 34.4% of the primary energy of the input fuel, such as coal, natural gas, uranium, petroleum, solar thermal, or biomass, reaches the consumer via electricity, although the efficiency can be 20% for very old plants and 45% for newer gas plants. In contrast, a CHP system converts 15%–42% of the primary heat to electricity, and most of the remaining heat is captured for hot water or space heating. In total, over 90% of the heat from the primary energy source (LHV based) can be used when heat production does not exceed the thermal demand.
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Micro combined heat and power AI simulator
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Micro combined heat and power
Micro combined heat and power, micro-CHP, μCHP or mCHP is an extension of the idea of cogeneration to the single/multi family home or small office building in the range of up to 50 kW. Usual technologies for the production of heat and power in one common process are e.g. internal combustion engines, micro gas turbines, stirling engines or fuel cells.
Local generation has the potential for a higher efficiency than traditional grid-level generators since it lacks the 8-10% energy losses from transporting electricity over long distances. It also lacks the 10–15% energy losses from heat transport in heating networks due to the difference between the thermal energy carrier (hot water) and the colder external environment.
The most common systems use natural gas as their primary energy source and emit carbon dioxide; nevertheless the effective efficiency of CHP heat production is much higher than of a condensing boiler, and thus reducing emissions and fuel costs.
A micro-CHP system usually contains a small heat engine as a prime mover used to rotate a generator which provides electric power, while simultaneously utilizing the waste heat from the prime mover for an individual building's space heating and the provision of hot domestic water. With fuel cells there is no rotating machinery, but the fuel cell's stack and where applicable also the reformer will provide useful heat. The stack does generate DC power which is converted by DC/AC inverter into mains voltage. Micro-CHP is defined by the EU as less than 50 kW electrical power output, however, others have more restrictive definitions, all the way down to <5 kWe.
A micro-CHP generator may primarily follow heat demand, delivering electricity as the by-product, or may follow electrical demand to generate electricity, with heat as the by-product. When used primarily for heating, micro-CHP systems may generate more electricity than is instantaneously being demanded; the surplus is then fed into the grid.
The purpose of cogeneration is to make use of more of the chemical energy in the fuel. The reason for using CHP systems is that large thermal power plants which generate electric power by burning fuel produce between 40% and 60% low-temperature waste heat, due to Carnot's theorem. The temperature produced by this waste heat (around 80 °C - 150 °C) does allow it to be used for space heating purposes, therefore in some urban areas district heating networks have been installed. Heat networks have a limited extent, as it is not economical to transport heat long distances due to heat loss from the pipes, and it will not reach into areas of low population density, or else revenues per CAPEX will go down. Where no district heating is possible due to low heat demand density or because the local utility has not invested in costly heat networks, this thermal energy is usually wasted via cooling towers or discharged into rivers, lakes or the sea.
Micro CHP systems allow highly efficient cogeneration while using the waste heat even if the served heat load is rather low. This allows cogeneration to be used outside population centers, or even if there is no district heating network. It is efficient to generate the electricity near the place where the heat can also be used. Small power plants (μCHP) are located in individual buildings, where the heat can be used to support the heating system and recharge the hot domestic water tank, thus saving heating oil or heating gas. CHP systems are able to increase the total energy utilization of primary energy sources. Thus CHP has been steadily gaining popularity in all sectors of the energy economy, due to the increased costs of electricity and fuel, particularly fossil fuels, and due to environmental concerns, particularly climate change.
In a traditional power plant delivering electricity to consumers, about 34.4% of the primary energy of the input fuel, such as coal, natural gas, uranium, petroleum, solar thermal, or biomass, reaches the consumer via electricity, although the efficiency can be 20% for very old plants and 45% for newer gas plants. In contrast, a CHP system converts 15%–42% of the primary heat to electricity, and most of the remaining heat is captured for hot water or space heating. In total, over 90% of the heat from the primary energy source (LHV based) can be used when heat production does not exceed the thermal demand.