Combined heat and power (CHP) is more efficient from an energy standpoint than separate systems for heat and electricity production. The concept is based on the recovery of thermal energy that is ordinarily lost during combustion-based mechanical electricity generation.
Cogeneration power plants can be connected to a factory's power network, for example, so the electricity generated is used on-site; Surplus power can be sold to the local electricity network.
How does cogeneration work ?
CHP facilities have different objectives depending on the application:
- Industrial sites that use heat: At large sites, CHP units ranging in capacity from a few to several hundred megawatts are integrated into the process. For these users, the production of thermal energy has priority, and the size of the facility will be determined on the basis of its thermal needs.
- District heating: The production of heat is primary, and the electricity is a by-product. Consequently, the electrical power generated may be much greater than needed locally and can be sold to the electrical network.
- Hospitals and airports: A backup electric power supply may be a critical factor which can be satisfied by CHP.
- At shopping centres and hotels, backup electricity may be the primary need, but with more flexible requirements than those of hospitals.
- Buildings that are far removed from any electrical network, and ships: These applications can use CHP to provide electrical self-sufficiency. In this case, the heat is a by-product.
- Municipal waste incineration plants: Heat is produced year-round through the incineration of waste. The goal is to identify the best possible use of this heat.
