Biomass Boilers

What are

Biomass Boilers

Biomass boilers work on exactly the same principle as conventional gas or fossil fuel boilers whereby they create a flame to heat water which is then pumped around the heating system and to our hot water taps.

The big difference though is in what they burn to create the heat. Instead of relying on our limited resouce of gas, oil or fossil fuels and the resulting impact on the envirnment and climate change, a biomass boiler burns sustainably sourced wood pellets, chips or logs, plants and other organic matter, such as manure or household waste.

Whilst they do still emit carbon dioxide into the environment It releases carbon dioxide when burned (considerably less than fossil fuels though) using biomass in place of fossil fuels helps to prevent long-term climate change, since the carbon dioxide released during the combustion was actually absorbed while the tree was growing, so they are, in effect, carbon neutral.

Biomass boilers can be used in place of a standard gas or oil boiler whilst biomass stovescan be used to heat a single rooms, sometimes in conjunction with a back boiler to provide hot water.

Biomass Boiler Example

How does a biomass boiler work?

Like a traditional gas or oil boiler, a biomass boiler uses the fire from burning biomass pellets, chips or logs to produce all the heat required to produce the hot water needed to heat our homes.

The boiler iteslf is a large enclosed unit in which pellets or logs are burned and converted into heat which the heats the water which is pumped around the house to provide for heating and hot water requirements.

Pellets are fed into a fuel hopper at the rear of the boiler and are automatically fed into the combustion chamber as required. Alternatively, some boilers are built so that theyt can be manually stacked with biomass logs and topped up as required. A fan supports optimum combustion efficiency and regulates temperature.

To get a little bit technical, they use a process called gasification to produce heat. This means the fuel is initially burnt at temperatures of around 600˚C in order to release gases. In turn these gases are then re burned which allows the temperature in the chamber to reach around 1,200˚C. The mega-hot gases then pass through a heat exchanger to heat the water.

As with traditional boilers a pump then sends the water to the radiators as required and a thermostat controls the overall temperature.

What is biomass fuel?

The definition of biomass is: A renewable organic material that comes from plants and animals. Biomass contains stored chemical energy from the sun that is produced by plants through photosynthesis. Biomass can be burned directly for heat or converted to liquid and gaseous fuels through various processes.

The main componant of biomass is simply wood. However, other sources include food crops, grassy and woody plants, residues from agriculture or forestry, oil-rich algae, and the organic component of municipal and industrial wastes.

Is burning biomass bad for the environment?

Burning both fossil fuels (oil, coal, gas etc) or biomass will release carbon dioxide (CO₂) and a greenhouse gasses into the environment.

However, the plants and trees that are the source of biomass fuel capture almost the same amount of CO₂ through photosynthesis while growing as is released when biomass is burned This means that biomass can be promoted as a carbon-neutral energy source.

That said, there is still a degree of controversy in relation to the burning of biomass and it’s impact on the environment – you may want to do your own research on this.

What are the advantages of burning biomass?

The main advantages are:

Savings – Heating with biomass can be a lot cheaper than traditional fossil fuels (especially in these times of fuel crisis)
Grant Funding – Making a switch to biomass may qualify you for Government grants
Environmental – Biomass is considered carbon neutral and the Biomass Energy Centre states it can cut emissions by up to 96%

Does a biomass boiler need a chimney or flue?

Yes. As with any wood burning appliance you will require a flue that meets all the regulations.

This could be an insulated stainless steel flue pipe installed with the boiler or an existing chimney which may first need lining for safety and legal purposes.

How much does a biomass boiler cost?

Here’s the sticking point … biomass boilers don’t come cheap!

For a small manual-fed log-burning biomass boiler you’re looking at between £5,000 and £13,000 and a larger one costing up to £16,000.

For a small pellet fed biomass boiler you’re looking at a range of £15,000 to £21,000 with a larger one costing up to £31,000

Payback is obvioulsy going to take some time and, whilst grants are available, it’s unlikely these will cover the full cost.

How much will a biomass boiler save me?

When it comes to fuel costs and specifically in comparison to gas, oil and electricity at current (2023/24) prices, biomass fuel is much cheaper, with wood pellets costingaround a third of the cost per kilowatt hour (kWh) compared to oil and gas.

Installing a biomass boiler can therefore save you up to 40% on your energy bill (obviously this could vary significantly depending on specifics) and so will be much cheaper to run as an alternative to oil, gas and electricity.

Are grants available for biomass boilers?

As biomass boilers are classed as a low carbon heat technology they can be supported by Government grants in certain parts of the UK and within certain criteria.

At the moment grants of up to £5,000 are available if the criteria is met.

See our section on Energy Efficiency Grants and Boiler Upgrade Scheme for more information.