Substantial energy saving can be realized in large buildings througcogen unitht the use of combined cooling heat and power systems. Natural gas driven generators are used to create electricity, at the same time, the heat generated by that machine is extracted and used to provide building heat in the winter months and through the use of an absorbtion chiller, to provide chilled water to the building in the summer months. When using this type of system, the building is getting more energy extraction from the fuel delivered. This saves money!
Electricity is created on-site, reducing electrical demand. The absorption chiller, using heat to make chilled water displaces the electric required to drive compressors in electric chillers further reducing electrical demand. Buildings generally see their greatest electrical draw in the summer months. By providing the cooling with an absorber the greatest electrical draw is removed. While these projects can exceed $1M in cost they tend to provide substantial savings. Sometimes with payback periods of less than 5 yrs. Buildings that heat their building with a boiler and cool with a chiller tend to be the best candidates for cogeneration. These systems can save building hundreds of thousands of dollars per year.
Cogeneration is not for every building, but used in the right application can provide energy saving at the level seldom seen in other energy reduction measures.