Boilers that generate electricity

Domestic gas boilers that can simultaneously generate electricity and heat will be unveiled in the UK today, providing a lower-carbon option to power homes.

The so-called micro-combined heat and power (micro CHP) units look like ordinary wall-hung gas boilers, but as well as generating heat for radiators and water, they produce electricity as a byproduct.

Traditional boilers are highly efficient at generating heat within the home, with more than 90% of the energy in the fuel converted into useful heat. But conventional electricity generation is highly inefficient, with as little as 35% of the energy in the fuel burned in the power plant becoming electricity in the home. Most of the rest is wasted as heat in the power station, with a smaller amount lost in transmission across the national grid.

But the new micro CHP devices create enough electricity for a one-bar electric fire as a byproduct of heat generation. This reduces wastage, with 92% of the total energy in the gas converted into heat or electricity. The new CHP boiler will be able to produce around 1,800–2,400 Kwh of electricity a year, more than half of the typical gas-heated home's total demand, because the electricity is generated "on site" without the need for transmission which wastes power.

Larger micro CHP devices have been sporadically available in the UK for a number of years, but the Ecogen by Baxi – which will be launched today at London's Ecobuild show and will go on sale at the start of April through British Gas – is the first to be comparable in size to a conventional boiler. The units will cost around twice as much as a large regular boiler – likely around £5,000.

Unlike solar panels and wind turbines, the Ecogen does create carbon dioxide, since it burns natural gas. But by producing electricity alongside the heat, the device can reduce the carbon footprint of a typical three-bedroom home by around one tonne a year (or significantly more if replacing an inefficient 10-year-old boiler), according to the manufacturer.

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