Emissions Reductions
Use of a well designed and operated CHP package instead of conventional heat and electricity generating plant will always improve energy efficiency and significantly reduce carbon dioxide emissions: by using a sulphur-free gaseous fuel, there are also reductions in sulphur dioxide and oxides of nitrogen emissions.
The following table shows how the emissions savings can be estimated for two different packaged CHP units, one using a gas engine and the other using a gas turbine. In each case, the CHP unit provides 1.5kWh of heat for each 1kWh of electricity generated. The calculation estimates the emissions that are avoided had 1.5kWh of heat been provided by a gas-fired boiler and 1kWh of electricity been supplied from power stations burning fossil fuels. The actual emissions reductions will depend on the performance of the CHP unit selected and can be calculated using the data from plant monitoring once the system is operating
Estimated emissions reduction from packaged CHP | ||||
| Emissions in g/kWh for each kWh of electricity generated | ||||
| Gas-engine CHP | Small-scale gas turbine CHP | |||
| Carbon dioxide | Oxides of nitrogen | Carbon dioxide | Oxides of nitrogen | |
| Emissions from gas-fired boilers [a] | 240 | 0.0 - 1.0 | 240 | 0.0 - 1.0 |
| Emissions from power stations [b] | 685 | 1.8 | 685 | 1.8 |
| Total emissions for conventional heat and power generation [c =(1.5*a)+(1.0*b)] | 1045 | 1.8 - 2.8 | 1045 | 1.8 - 2.8 |
| Emissions from CHP packages | 650 | 2.0 - 10.0 | 750 | 0.2 - 0.5 |
| Emissions reductions achieved | 395 | (0.2) - (7.2)¹ | 295 | 1.6 - 2.3 |
¹Value in brackets represents a maximum increase in emissions
Note 1: The calculations are based on average boiler plant and electricity distribution capacity (including transmission and distribution lossess) in use in 1999.
Note 2: Carbon dioxide is often represented in terms of mass of carbon. To convert from carbon dioxide to carbon multiply by 12/44.
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