Micro CHP – Combined Heat & Power
This is a way of generating heat which will simultaneously generate electricity from the same fuel (typically gas) in the home.
You save money because you use the same fuel to generate electricity as you do to heat your home – and it qualifies for the Feed-In Tariff.
CHP stands for Combined Heat and Power. Until recently only large scale systems have been possible, but now there are systems that can replace a conventional home boiler. This is often referred to as Micro CHP. Large scale systems generate electricity and in doing so produce heat as a by-product. Micro CHP systems work in the opposite way – they generate heat and electricity is generated as a by-product. Micro CHP systems are very similar to boilers – the only difference is that they have the added capacity to generate electricity. They need to be fuelled either by gas or LPG (Liquid Petroleum Gas). There is only one type of micro CHP system available currently, which is known as the Stirling engine. The Stirling engine produces heat and electricity at a ratio of 6:1.
Micro CHP systems are particularly suited to older, larger homes where solid wall insulation isn’t financially viable. This is because the more heat they generate, the more electricity they generate and therefore the more they save you on your bill if you are producing the heat anyway. In a house like this, a micro CHP system can save you 5%-10% on your electricity bill, with an average saving of £60 a year.
Micro CHP systems are also eligible to receive payments for generating electricity under the Feed-In Tariff scheme for the first 30,000 installations. Under current tariff rates you can be paid 12.89p per unit of electricity (kWh) generated, adding up to an average payment of £180 a year. You can also be paid for the electricity you generate but don’t use as you can export it to the Grid. The current export tariff rate is 4.64p/kWh, adding to £30 a year on average. You are paid these payments at a fixed rate linked to inflation for 10 years. For more information on the FIT, visit our FIT page.
If you can’t afford to pay the installation costs for a Micro CHP system upfront you can get a loan for the costs through the Green Deal scheme. This government scheme gives loans for green home improvements that are paid back through the homeowner’s energy bills. The saving you make on your monthly bill by using the technology should be more than the payment amount. For more information on the Green Deal visit our Green Deal page.
- 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 big are micro CHP boilers?
- Typical CHP boilers are now comparable in size to most domestic boilers on the market.
- Can my home be disconnected from the National grid if I use a micro CHP unit?
- No, the house will need to remain connected to the main supply - the unit won't be able to meet all of your electricity needs. As the micro CHP boiler is a gas-fired boiler, the gas connection must also remain in place.
- Will the unit use less gas than a high-performance boiler?
- By using the micro CHP boiler, gas consumption will increase a little despite waste heat being used to generate the electricity. However, on balance you will still save energy, as you can generate a significant amount of electrcity suing the system.
- 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.
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