Combined Heat and Power

CHP is not classified as a renewable technology as it needs a fossil fuel source, but it is an extremely efficient way of generating both heating and electricity in a single piece of equipment so it is a genuinely low carbon solution.

It converts up to 85% if the fuel it receives into useful energy i.e. heat and electricity compared with the 22% to 25% delivered by conventional ‘centralised’ power generation so cutting carbon emissions by around 30%.

It has the added benefit of making the user largely self-sufficient because they are able to generate their own electricity where they need it i.e. on site. As well as providing security of supply, this also avoids the transmission losses experienced by mains generated power.

Varieties
A number of varieties are available including internal and external combustion engines (Otto or Stirling) and steam-based turbine systems. In the future, it is expected that CHP plant will also be fired by hydrogen fuel cells providing a truly sustainable solution.

The ‘primary’ fuel – oil or gas – drives a generator that produces electricity. The process creates heat as a by-product and this is captured and used to heat occupied areas and water. Originally, CHP units were normally deployed in large buildings or industrial complexes like waste incineration plants, but the technology is now available in ‘mini’ systems for domestic and small commercial premises.

Eventually, CHP units could provide 100% of the heating and 80% of the electricity needs of many buildings so reducing their carbon emissions by 40%.

Issues to consider:

Sizing the system is critical and a large heat demand required to ensure the system is running almost continuously generating electricity.

Installation of CHP systems is not inherently complicated, but does require an engineer with sound understanding of the technology and how it can be applied to provide a balanced heating and power solution.