How does Micro CHP work?
Combined Heat and Power (CHP) systems are highly efficient, making use of the heat generated by your heating system. This produces electricity for your home that would otherwise require you to burn additional fuel, thus saving energy and money!
Micro CHP systems contain a condensing boiler that heats water for your hot water and heating needs. Most domestic micro CHP systems will have two burners, one small (engine burner) and one large (supplementary burner).
Technical information made simple
There are 3 main micro-CHP technologies, and the main one in use today in a domestic setting is the Stirling engine. The others, Internal Combustion engine and Fuel Cell, are still being developed for use in domestic environments and are not very common today.
Stirling Engine micro-CHP is relatively new to the market and is being installed in homes in the UK. The technology was pioneering in the 19th Centenary by Robert Stirling and relies on the expansion and contraction of heated and cooled gas to drive a piston which in turn drives a generator to produce electricity. The gases are heated by steam produced by the Micro CHP’s condensing boiler as it heats the water. Stirling engines are both efficient and quiet. A standard Stirling engine can meet around half of an average home’s electricity needs. To maximise efficiency, it’s essential you choose the right sized system for your house – too large and you won’t use the system enough to generate much electricity.
Micro CHP systems are designed to be able to replace your existing boiler and are of an equivalent size, but will need to have an electricity connection. It must be fitted by an accredited installer to qualify for the Government’s finance schemes.
Find out more about the Installation of Micro CHP here.
- What savings do micro CHP boilers produce?
- Overall, micro CHP boilers use slightly more gas than standard boilers. However, the micro CHP generates enough electricity that total energy costs are reduced by 20%. Moreover, carbon dioxide (CO2) emissions per unit of electricity generated are over 50% lower than if the same amount of electricity were to be generated by a large power station.
- How long does it take to recoup the additional costs associated with buying a micro CHP boiler (compared with a high-performance boiler)?
- It is expected that the payback will be five years more, although this will depend on many factors, so it is difficult to give a definite answer.
- Is it possible to return any excess electricity produced by a micro CHP unit to the grid?
- Yes, it is possible to return surplus electricity produced by a micro CHP unit to the grid - you will receive Feed-In Tariff Export tariff payments for doing so if you have your system installed by an MCS accredited engineer and sign up to the scheme.
- What happens to the electricity that is generated by a micro CHP boiler that I don't use?
- Surplus electricity is returned to the electricity grid. You can receive payments for this electricity through the Feed-In Tariff scheme if your installation is carried out by an MCS certified installer - find out more about this on our Feed-In Tariff pages.
- What maintenance does a micro CHP boiler require?
- The maintenance for a micro CHP boiler is similar to that of a normal boiler – i.e, you should ideally have it serviced annually.
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