Micro CHP

By Katie Anderson on September 5th, 2011

Micro combined heat and power – more commonly known as Micro CHP – is heating technology which generates electricity and heat at the same time and from the same energy source.

A micro CHP appliance may look and work in much the same way as a traditional gas central heating boiler, heating a home’s heating and hot water system. But unlike a boiler, at the same time as providing heat, a micro CHP system also generates electricity which can be used in the home or exported to the national grid.

The amount of electricity that can be generated is dependent on how long the system is running. Once warmed up, a typical domestic system can generate up to 1kW of electricity per hour which, in a typical home, would be sufficient to power appliances and lighting.

Despite domestic micro CHP systems using fossil fuels (mains gas or LPG as a heating fuel)  the technology is referred to as ‘low carbon technology’ because it is still essentially more efficient than just burning fossil fuels for heat and getting electricity from the national grid.

There are three main types of micro CHP technologies:

  • Stirling engine – the newest form on the market, and ideal for domestic applications, they are very efficient and benefit from a short warm up period before they start producing electricity.
  • Internal combustion engine – mostly used in larger commercial-scale applications, this technology is the most proven of the three. Literally truck diesel engines have been modified to run on heating oil or natural gas, which are directly connected to an electrical generator.
  • Fuel cell – still at a developmental stage, energy is taken from fuel at a chemical level, instead of burning it.

Is micro CHP suitable for my home?

There are a few things you will need to consider if you are thinking of implementing this form of renewable energy technology in your home:

  • Most Micro CHP units are wall-hung, so you will need the appropriate wall space. Units can be fitted in kitchens, utility rooms, airing cupboards and even garages.
  • If you already have a conventional boiler then there shouldn’t be a problem having the technology installed; a micro CHP unit is roughly the same size.
  • You’ll need to review your annual heat consumption. These systems are most cost effective in properties with large heat demands that cannot implement insulation measures, such as draught proofing.
  • For older properties which have a higher than normal heat load, a micro CHP system could well be a viable option.

How much will it cost?

It will vary, but installation costs for a typical micro CHP system will cost from £5,500.

Top Facts

1. The first micro CHP units became available in the UK in 2004.
2. Typically, around 70-80% of the energy value of the gas is converted into heat, with 10-25% converted into electricity and 5-15% lost in the flue gases.
3. They emit less carbon compared to a conventional power station.
4. If the micro CHP appliance has MCS certification, you’ll be eligible for the feed-in tariff (Fit) scheme, which pays you money for generating your own electricity.
5. It is anticipated that micro CHP has the potential to provide around 20% of the UK’s electricity generating capacity – which is more than is currently obtained from nuclear power.
6. Micro CHP units can work effectively and efficiently in small offices, apartment blocks, small high street retail units and small hotels.
7. A 2008 survey by Claverton Energy Group found that Stirling engined micro CHP technology was deemed the most cost effective of the various microgeneration technologies in reducing carbon emissions in the UK.
8. Domestic micro CHP systems use mains gas or LPG as a heating fuel. They can also be powered by oil or bio fuels.

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