Burning fossil fuels has been the staple for heating homes across the world for millennia. However, increased pressure on homeowners to reduce carbon emissions has seen a shift to renewable sources of energy and an investment in improving energy efficiency. One option for many homes is to install a Biomass heating system. There are several industrial-sized biomass heating systems, alongside biomass electricity generators in many UK cities, but companies are improving and refining the systems for use in the average UK home.
What are Biomass heating systems?
Biomass boilers are very similar to conventional gas boilers that you will be familiar with, providing you with space heating and hot water for the entire home, but instead of using gas (or oil) to produce the heat, they combust sustainably sourced wood. There are three Main Types of Wood Fuel:
- Wood pellets are the most common type of domestic biomass fuel and can be packed and delivered in bags or bulks. Buying larger quantities at once is often cheaper than otherwise.
- Wood chips are more expensive when it comes to transportation as they are less dense compared to pellets. In addition, they are only appropriate for homes that have space to store them.
- Logwood is a source of energy relatively stable in price. Logs and other types of wood fuel are the first choices for those who are conscientious of their impact on the environment.
Every four weeks or so, the biomass boiler will need to be emptied of the ash. This can be put straight onto a compost heap to help fertilize the soil. Biomass boilers are designed to work all year round; however, you may choose to turn them off in the summer and use an alternative heating source, such as solar.
Why is Biomass a good option?
- Affordable heating fuel – Although the price of wood fuel varies considerably, it is often cheaper than other heating options. You can also source your own fuel rather than relying on national suppliers. In more remote areas a well-stocked log pile will keep a biomass heating system running for many years without the need to purchase wood elsewhere.
- Financial support – Wood fuel boiler systems could benefit from the Renewable Heat Incentive (RHI). These government subsidies will vary for the type of property and expert advice should be sought.
- A low-carbon option – The carbon dioxide emitted when wood is burned is the same amount that was absorbed over the months and years that the plant was growing. The process is sustainable as long as new plants continue to grow in place of those used for fuel. There are some carbon emissions caused by the cultivation, manufacture, and transportation of the fuel, but if the fuel is sourced locally, these are much lower than the emissions from fossil fuels.
MCS-approved pellet fired, or gasification biomass boilers are comparable with the most efficient conventional gas boilers and, through the Renewable Heat Incentive, they produce a very healthy return (provided the heat demand on your EPC is sufficient). Therefore, provided you have space to house the fuel and the boiler itself and you are happy that you are going to have to ‘feed and clean’ the boiler on a regular basis, then a biomass boiler is certainly worth considering.
Also Read: Going green at home?
Obviously, they are very expensive to buy upfront, so this too is something you must bear in mind. If you have access to cheap finance, then installing a biomass boiler could be a no-brainer!
Costs and potential savings
Biomass boilers start at about £7,000 for a 12kW domestic version, which is sufficient to provide heat and hot water for a 4-bed house. A comparably sized gas boiler will only cost around £2500 to install. A bigger biomass boiler with an auto-feed hopper may cost closer to £12,000.
In terms of the cost of fuel, the average price of wood pellets is around 4.2p/kWh which is very much in line with mains gas, while oil costs a little more at 6p/kWh. However, the price of wood pellets is likely to become more attractive going forward since gas prices have continued to rise in recent years, and this trend looks to continue. Biomass boilers are completely independent of the fluctuating import prices of foreign fuels such as gas and oil.
However, if you are lucky enough to have a free supply of wood, then you can heat your home at zero cost. Maybe it’s time to consider planning your own patch of woodland or buying one which has permission for sustainable felling and clearing. The other option for those in urban areas is wooden pallets; these are often available for free from building yards and depots. However, care needs to be taken with these as some have been treated with chemicals and painted which will then release noxious fumes when burned.
Other things to consider
- Wood boilers are larger than gas or oil equivalents and you will need space to store the fuel. This area will need to be somewhere that’s handy for deliveries as well as appropriate for feeding the boiler.
- You will need a flue which meets the regulations for wood-burning appliances. This could be a new insulated stainless-steel flue pipe or an existing chimney, though chimneys normally need lining to make them safe and legal.
- You may not need planning permission, but you should always check. All new wood heating systems must comply with building regulations, and the best way to ensure this is to use an installer who is a member of a competent person scheme.
- Biomass boilers and stoves should be kept clean and swept regularly to remove ash. Ash quantities are generally very low (less than one per cent of fuel volume), but you will still need to empty the ash bin of a wood burning stove or boiler. This is likely to be weekly and never more than once a day. A log fire requires ash removal before every use.
- Biomass boilers are much bigger than conventional boilers, since they will have to have some element of an auto-feed option. In the case of the Baxi Bioflo, it is 1.2m high, while a conventional gas boiler is half the size.