Cogeneration

What is Cogeneration?

Cogeneration, sometimes called Combined Heat and Power (CHP), simply means the sequential generation of power and useful heat.  “Power generation” can be electrical or mechanical, although it most usually is electrical power.  “Useful heat” means heat that is presently being produced and used in a facility, such as steam, hot water or other form of heat.  This technology, if properly engineered and implemented, can result in substantial savings to the host organization.

There are three basic thermodynamic cycles of cogeneration, as follows:

1. Topping cycle:  start with power generation; use waste heat. (gas turbine or engine)

2.  Bottoming cycle:  start with waste heat; recover to generate power. (steam turbine)

3. Combined cycle:  combination of topping & bottoming cycles. (gas turbine/steam turbine)

The topping cycle is the most commonly employed configuration in industrial and institutional facilities, with the primary generation being electrical power and the secondary generation being steam.  Gas turbines are useful for expelling high-quality waste heat, suitable for producing steam, while engines are most useful in the 200F waste heat range, suitable for generating hot water.

The heat need of a facility is a controlling factor in the economic viability of Cogeneration.  The cost of generating power on-site can be less than the cost of purchasing power only if the waste heat is utilized effectively. In this regard, the incorporation of heat-driven chilling capacity is often a cost effective addition to a Cogeneration system.  If the facility in question will be in need of additional chilling capacity in the near future, a steam-driven chiller (either absorption or steam turbine) could be a viable way of displacing more electrical power while efficiently utilizing all of the waste heat of the Cogeneration prime mover.       

The usual application of Cogeneration is to operate the system in parallel with the electrical utility, providing an additional layer of redundancy on electrical power supply to a facility.  The interconnect configuration must be approved by the utility.  Proper coordination with the utility is very important for a successful project.    

What Services Can Project Solutions Provide?

Cogeneration Feasibility Questionnaire