Biomass: Everything You Need to Know

Find out everything you’ve wondered about Biomass from our all-encompassing guide.


Biomass heating systems use renewable fuel sources – mainly wood – to produce heat for heating single rooms or powering central heating systems, or to provide your domestic hot water.

 Why Choose Biomass?

There are two main benefits to using a biomass heating system, both of which are significant enough to make anyone consider switching to biomass.

Low cost:

Electric, oil, and gas heating can be extremely expensive, and as we witness our bills rising year upon year now could be the time to quit the fuels rat race. Wood, a simple and abundant material, remains affordable and is renewable, meaning that there is no reason for costs to rise against dwindling resources as is happening with the fossil fuels we have been using.

Smaller carbon footprint:

Your CO2 emissions will be cut by a considerable amount just by switching to using a biomass heating system. What’s wonderful about using wood fuel is that the carbon dioxide that is released by the burning wood is equal to the amount which is absorbed during the time the tree takes to grow, making biomass a highly sustainable option as long as trees are planted to replace those which are cut down for burning.

Biomass Fuels

Biomass fuel is used as an alternative to the common fossil fuels such as gas and oil, which we have relied on in the past. Biomass is renewable, and therefore a much more environmentally friendly fuel to useThere are many different biomass fuels to choose from, and some are better suited to certain equipment, lifestyles, and budgets than others.


Wood is the main kind of biomass fuel in use today, no matter what form it takes. The cheapest kind of wood fuel you are likely to find is logs. These can usually be sourced relatively easily, and at a reasonable price. Wood value tends to fluctuate, so if you can catch it at a low ebb you might consider stocking up for the foreseeable future.

Picking the right logs does take some consideration. When choosing which wood to go for, it is important that you find some of a suitable density and moisture content. If these are too high, or too low, they can negatively affect your biomass system and they won’t be able to provide the energy-saving benefits that can be expected of a properly fuelled, well-maintained system.

Wood Pellets

Wood pellets are a kind of biomass fuel made of compacted sawdust and other waste wood materials. Sometimes the pellets are formed using trees grown especially for their production, and the fuel can be used industrially, commercially, and residentially.

There are some great reasons to decide to opt for wood pellets, beginning with the fact that they are considered to be the most environmentally friendly solution to our fuel needs. The pellets burn very efficiently, and have a moisture content of below 10%. When burnt, this fuel will produce a minimal amount of CO2 emissions.

Wood Chips

Wood chips are simply cut-down pieces of larger timber chunks. They are not compressed like pellets, so they do take up a little more room. If you buy wood chips, make sure to attempt to remove any ‘slivers’ from the supply before burning. Slivers are long, thin pieces of wood which can cause blockages in the chip feed system of your biomass heating.

Chips are more efficient than logs as they provide a greater surface area, and are also easier to handle in small amounts. This is perfect for those who need to store their fuel away from the burner.


Miscanthus is a kind of grass usually found growing on the banks of the Nile, where it is used as a cooking fuel. However, in the UK we have seen rising numbers of people using this natural resource as a biomass fuel to heat homes and water.

Otherwise known as Elephant Grass, Miscanthus will usually need to be burnt in a purpose-made boiler which is able to handle the unique properties of the fuel. Some wood burning biomass boilers may be able to handle the fuel anyway, but check that out with your manufacturer before going ahead and burning.

The obvious benefits of using miscanthus are:


Using miscanthus as a biomass fuel is very cost-effective, with savings of up to 87% to be expected when replacing fossil fuels such as gas or oil.

Energy efficiency:

Just 1 tonne of miscanthus will provide 4mWh of heat, which is comparable to the heat produced by 400 litres of the heating oil many of us currently use.

Growth and renew-ability:

Miscanthus is ideal for growing as a fuel source due to its high rate of growth and its very low demands. The plant can grow in what is usually considered infertile land, and it barely requires water. Research into the plant has demonstrated that it is able to absorb CO2, and due to the fact that it is a sterile hybrid it can grow completely non-invasively when introduced here in the UK.

Storing Wood Fuel

The main consideration when it comes to storing wood fuel is the need to keep it completely dry. It doesn’t matter so much where the store is located as how well it protects the fuel. However, it is important to bear in mind that the further away the fuel is stored, the further you will need to travel and the further you will have to carry it.

If you are growing your own wood fuel it is important to have somewhere to allow it to season before it can be burnt. The seasoning process is necessary as it allows the wood to lose some of its moisture content. Wood with a high moisture content will not burn well, and could impact upon the performance of your biomass boiler.

Build your own wood store:

One simple way to create a space to keep your wood fuel until it is needed is to collect some old wooden pallets, and build your own pallet wood store. These are ideal for keeping logs up and off the ground, and giving them time to dry out before they are needed for burning.

Biomass Burners

There is no one piece of equipment to fit all kinds of biomass fuel, and the different types available have different uses for the people who use them.


A wood burning stove is the traditional fireplace wood burners which most people will recognise. They are usually available in heavy, black varieties, and can be found very easily. Having been in use for many years, stoves are well-trusted and their appeal lies largely in their traditional design. Offering an efficiency rate of 80% compared to a rate of 50% for an open fire, stoves are not wasteful of money either.

Some stoves are capable of running 12 radiators and most – though rarely all – of a home’s domestic hot water. Often, a backup source of oil, gas, or solar power, can be used to supplement the stove in producing hot water.

When picking a stove, make sure it is suited to the kind of fuel you will use. You will find that there are different kinds of wood-burning stoves and pellet-burning stoves. Wood pellet stoves can be quite bulky, so be sure to consider the size of the pellet stove and where it might fit in your home.


Biomass boilers are able to run at efficiencies of up to 90%, and are able to supply all of your domestic hot water and heating water. Although they are not as ‘attractive’ as the stoves we are used to, they are much more efficient, and can be left to operate unaided for extended periods of time.

One of the main differences between stoves and boilers is that a boiler can be fed automatically. This is usually only possible with a large model, but these can be fitted into a home provided there is space to store the fuel relatively nearby. Potential storage solutions can be found in adjacent garages, or other spacious outbuildings near to the house. Manual systems will have to be fed by hand, so keeping the fuel nearby is still a good idea. Fuel can be difficult to manoeuvre over longer distances.


As with any major heating system, biomass boilers or stoves must be fitted by a professional. An experienced installer will also be able to answer any additional questions you may have, so be sure to take advantage of their expert knowledge. Cover these key questions to make sure you know the important things.


Biomass is fairly easy to deal with, but it is important that your system is kept well maintained and serviced.The most important maintenance you must carry out when using a biomass burner is to remove the ash that it creates.

Ash is a highly insulating material, and it gets stuck inside the steel components of biomass burning systems. The coating this creates can have quite an impact on the system’s heat output, meaning that more fuel will be needed to reach the desired temperature. As ash build-up occurs, the flue temperature will increase, so keeping an eye on this temperature will help you to detect when the system needs to be cleared.

Removing ash is not the only maintenance required. To keep your burner working as best it can, it is recommended that you have it serviced by a certified engineer. They will be able to spot any issues before they become serious or expensive to fix. Get the professionals in once or twice each year to service the boiler: they will de-ash, lubricate the combustion fan actuators, and sweep out the flue and chimney too.

This is all worth doing in order to keep the boiler running as well and as cost-effectively as it can. In the long run, it can be much more costly to deal with the issues associated with not carrying out these simple maintenance checks.

However, modern boilers are developing to be less dependent upon servicing, and are beginning to be able to run at efficiencies of 90-93% without so often being serviced.

Domestic Renewable Heat Incentive (RHI)

A major benefit of using renewable energy is the financial rewards you can receive for doing so. The government is pushing renewables, and in 2014 is opening up its Domestic RHI (renewable heat incentive). The incentive will be available to anyone who has fitted an eligible heating system since 15 July 2009.

Image by James.

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