Simply put, co-generation is an environmentally and economically sound method of recycling heat that is typically produced during the course of electricity generation. It allows fuel efficiencies of up to 80-90% compared to 30-35% for utility power plants.
In a typical co-generation plant, a gas turbine will burn natural gas to drive an electrical generator. It will produce electricity at an efficiency of 35-43%. The hot turbine exhaust, instead of being vented up a stack and wasted, will flow through a boiler to generate steam that will be used in a process plant, commercial facility or for district heating. The additional heat that is recovered will add 45-50% to the fuel efficiency of the system, yielding an overall fuel efficiency of 80-90% (actual co-generation scheme efficiencies will vary depending on the equipment selected and other factors).
Efficiency and Environment. These are the key advantages of cogeneration. Without cogeneration, a process plant would typically purchase electricity from a local utility, and burn carbon-based fuel in a boiler to generate steam for the plant. The electricity sold by most conventional utilities is produced at central plants located a considerable distance from the user. Electricity produced at conventional utility plants typically incurs considerable heat loss (60-70%) when the steam from its steam turbine generators is cooled and condensed. Such plants thus have only 30-35% fuel efficiency, and emit large quantities of greenhouse gases to atmosphere. When the electricity is transported long distances over electrical transmission and distribution lines to the users, further energy is lost due to the resistance of the wires, and stray currents are emitted. A process plant that requires steam would also use additional fuel in a boiler, and the boiler flame would release further greenhouse gases to atmosphere.
Capture waste heat. With the sequential generation of power and heat in a cogeneration/CHP scheme, up to 90% efficiencies can be realized, with only 10% left over as waste heat. This technology is driving future power generation installations, and can offer substantial economic benefits to industrial and commercial enterprises.
Heating and cooling. The same technology can be used to deliver cooling by using absorption chilling technology. Thus it is possible to do "tri-generation," the production of electricity, heat, and cooling from a single fuel source. Tri-generation technology is particularly attractive for commercial and institutional facilities that have heating and cooling loads, and for industrial applications with process heat and refrigeration requirements.
o-generation, also known as Combined Heat and Power ("CHP"), means the production of two forms of energy (electricity and heat) from a single fuel source.