Many sources of biomass can be used to heat a house, including plants, residues from agriculture or forestry, and the organic component of municipal and industrial wastes – even the fumes from landfills can be used as a biomass energy source – but wood-fuelled systems are still the most popular biomass method. These burn wood pellets, chips or logs to provide warmth in a single room or to power central heating and hot water boilers.
When a tree is burned it omits the same amount of carbon dioxide absorbed during its lifetime – the same amount as if allowed to rot naturally. As long as the wood used is sustainably sourced, this is a carbon-neutral process.
A stove burns logs or pellets to heat a single room and may be fitted with a back boiler to provide water heating as well. A boiler burns logs, pellets or chips, and is connected to a central heating and hot water system and, according to the Energy Saving Trust, could save you up to £650 a year compared to electric heating.
An individual pellet stove will cost around £4300 including installation. For boilers, an automatically fed pellet boiler for an average home costs between £14,000 and £19,000 including installation, flue and fuel store, and log boilers between £11,000 and £23,000.
Pellet costs depend mainly on the size and method of delivery and buying a few bags at a time makes them expensive. Having a space to store several tonnes of pellets at a time will keep costs down. Logs can be cheaper than pellets, but costs depend on the wood suppliers in your local area, as they cost a lot to transport. If you opt for a wood-burning stove, consider buying unseasoned logs and letting them season for a year to save money.
A long-term investment
Savings in carbon dioxide emissions are very significant – up to 14.5 tonnes a year when a wood-fuelled boiler replaces a solid-fired system or electric storage heating. This technology is an eligible measure under the UK government’s Green Deal which is a financing mechanism that lets people pay for energy-efficiency improvements through savings on their energy bills.
Thanks to the domestic Renewable Heat Incentive, homeowners installing a biomass boiler could secure a tax-free payment of nearly £60,000 at a potential ROI of 64%. Natural Energy Company, Euroheat, has calculated that homeowners investing £35,000 in a domestic RHI biomass installation could see them potentially clock-up a return on investment of £57,645 over a seven year period plus an expected on-going reduction in fuel savings, and a boiler that will last two decades.