cogeneration

Cogeneration, or combined heat and power (CHP), is the simultaneous production of electricity and useful heat from a single energy source. By recovering waste heat, CHP achieves higher overall efficiency than separate generation of electricity and heat.

A CHP system uses a prime mover—such as a natural gas–fired turbine, engine, steam turbine, or fuel cell—driving a generator. The remaining heat is recovered to produce steam, hot water, or hot air for heating or industrial use.

Configurations include topping cycles, where electricity is produced first and waste heat is used for heating or processing, and bottoming cycles, where heat from a process drives electricity generation. CHP technologies include gas turbines, engines, steam turbines, microturbines, and fuel cells.

Electrical efficiency for CHP typically ranges from 25 to 45 percent, while the overall system efficiency—electricity plus usable heat—can exceed 70 percent and may reach 85 to 90 percent when heat is fully utilized.

Benefits include higher fuel utilization, lower energy costs, reduced emissions per unit of energy, and greater resilience. CHP supports districts, campuses, and industrial facilities by providing on-site power and heat.

CHP has roots in the 19th century and has achieved widespread adoption in Europe, North America, and Asia as a means to improve energy efficiency and manage peak demand.

Challenges include higher capital costs, the need for a consistent heat load, and integration with existing systems. Proper siting, control, and maintenance are essential for maximizing performance.

Related topics include district heating, energy efficiency, and microgrids.