cogenerating

Cogeneration, or combined heat and power (CHP), is the simultaneous production of electricity and useful heat from a single energy source. By capturing heat that would normally be wasted in electricity generation, CHP systems can achieve higher overall energy efficiency than conventional separate heat and power production.

A CHP plant uses a prime mover—such as a natural gas turbine, diesel or gas engine, steam turbine, or fuel cell—to generate electricity. The remaining heat from exhaust, coolant, or other streams is recovered in a heat recovery unit and supplied as steam, hot water, or direct process heat for on-site needs or district heating networks. The heat use is typically integrated with the facility's process or space conditioning.

CHP systems are often described in terms of topping cycles or bottoming cycles. In a topping cycle, electricity is produced first from the fuel, and the resulting heat is recovered for heating or process use. In a bottoming cycle, a primary heat source drives a turbine to generate electricity from the waste heat of an industrial process.

Efficiency and economics: CHP systems commonly achieve overall efficiencies of 60% to 90%, with electrical efficiencies of 25% to 45% and the heat recovery raising total efficiency well above conventional on-site generation. They can reduce fuel consumption and greenhouse gas emissions per unit of useful energy, especially when there is a steady demand for heat.

Applications include industrial facilities, institutions, hospitals, district heating, and remote or microgrid environments. Challenges include capital cost, load matching, and integration with existing energy systems, as well as regulatory and maintenance considerations.