Combined heat and power generation system

Combined heat and power generation system
© Kaspars Grinvalds, image #78741327, 2017, source:
All sectors
Investment cost:
High cost
Payback time:
2.8 Year(s)
Cost savings:
52277€ / Annual: € 52 277.49 (£ 47 961)
Resource type:
Resource saving:
Annual: reduced gas and electricity costs; replacing existing unit; 190 090 kg CO2 equivalent saved
Investment cost:
147150€ / € 147 150 (£135 000) per project; the scale of the project is based on heating demand; operates best with constant gas and electricity base load and relatively long operational hours; regular boiler checks required
Assumptions taken in the presentation of the above performance indicators:

Installation of a gas CHP engine to replace conventional gas boilers; applicable where a constant heat and power base load is apparent on-site; suited best to sites with long operational hours; installation of CHP rated 135 kWe and 217 kWth to replace existing gas boilers and offset an electrical base load in use of 7 500 hours per annum

Combined heat and power (CHP) helps to reduce total fossil fuel consumption from on-site boilers and the power stations they import electricity from. As such, CHP systems help to cut energy bills and the environmental footprint of a company. Recorded primary energy savings from CHP are around 18 %, and 28 % for small packaged CHP schemes.

A CHP system generates usable heat and power within a single process. The power can either be electrical or mechanical (i.e. for driving equipment such as pumps, compressors, and fans). There are three steps in CHP: power generation, heat recovery, and heat use. At the heart of CHP is the prime mover (or heat engine). It is usually a gas turbine, steam turbine or internal combustion engine. Given the diversity of prime movers and fuel used, CHP is flexible and can address various heat demands (e.g. hot water, steam, etc.). This means it can be tailored to the requirements of various sites and used across a wide range of sectors for large and small energy users alike.

CHP only generates economic and environmental savings when it is running, so the system is most viable when the demand for heat is at least 4 500 hours per year. CHP can also be advantageous when demand for heat is low but demand for cooling is high. In this case, heat from a CHP plant can be used for cooling by using an absorption chiller unit.

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