Combined heat and power (CHP) systems, also known as cogeneration systems, provide both heat and power from a single source of energy; working to the principles of a Stirling engine. CHP is a type of distributed generation, which, unlike central station generation, is located at or near the point of consumption.

By using the heat created, which is normally a by-product that would be lost, CHP systems typically achieve efficiencies greater than 80%. It therefore makes sense to consider CHP units when there is a need for both power and heat at a site. The CHP technology can be deployed quickly, cost-effectively, and with few geographic limitations.

The term CHP covers a suite of technologies that can use a variety of fuels, e.g. biomass or gas, to generate electricity or power at the point of use.

A CHP system can be added to most heating systems, where the primary goal is to generate space and/or water heating. The benefit of a CHP system is that it can generate electricity from the by-product of burning the fuel (e.g. biomass or fossil fuel). In a typical high temperature heating system the burning process produces steam. This steam is then channeled to drive a gas or steam turbine which subsequently generates electricity. The waste heat produced is captured from the exhaust gases or steam. It is then injected into the site’s heating system at between 60°C – 90°C or utilized in an industrial process.

The CHP system will produce more heat than electricity. As a rule of thumb and to be economically viable, there should be stable baseload demand for heat in excess of 5,500 hours per year. A CHP unit will also operate most efficiently with minimum wear when at full constant load. This means that correctly sizing the CHP units is very important. As such, a CHP system that is too small will not deliver the full cost savings and if the CHP is too large it will struggle to meet its minimum load threshold to operate efficiently.