A biomass boiler has the same function and mode of operation as a conventional gas boiler. However, instead of burning gas or oil to heat your space and water, it burns biomass, which are sustainable plant materials. These plant materials are mostly wood chips and pellets, which can generate heat or electricity for your home.
They are a low-carbon and renewable energy sources designed to replace coal, gas, and oil burners. When you replace fossil fuels with wood, you help in the fight towards climate change. The wood is carbon neutral as the carbon dioxide it releases when it burns is what the tree absorbed when it was growing.
The Greenage estimates that about 8.5 million tonnes of wood finds its way into landfills in different parts of the UK. Instead of filling up landfills, the wood can go into biomass burners or can be used in standalone stoves.
How Do Biomass Burners Work?
Biomass boilers are relatively big. These boilers burn wood pellets, which need more space than gas, and thus the big size. In homes that need a lot of hot water, the boiler needs to be big to hold a large volume of fuel.
You can convert biomass to energy through any of the following methods:
- Chemically to create liquid fuels
- Directly burning the pellets, logs, or chips to produce heat
- Biologically to create liquid and gaseous fuels
- Thermochemically to create solid, liquid, and gaseous fuels
There are different materials that can be used to produce fuel.
These sources include:
- Wood and waste products from processing of wood. These include wood pellets, chips, logs, sawdust from lumber mills, and black liquor from paper and pulp mills.
- Biogenic materials from plants released as waste products, including paper, cotton, food, wood wastes, and yard waste among others.
- Crop wastes, such as corn, soybeans, sugar cane, woody plants, food processing residue, algae, and many more.
- Manure from animals and human wastes
If you are using pellets for your biomass boiler, you will receive pellets once or twice a year in your silo tanker. If you have a room of about 4.5 square metres, you can keep enough pellets to warm a single-family room for a year.
From the storage room, the pellets move through a pellet feed into the boiler. The boiler burns these pellets to produce heat. What remains after the combustion process is ash, which is only 0.5 percent of the weight of the original wood. In some biomass boilers, the system connects to a buffer storage that reduces the emissions from the system and increases the efficiency of the system.
The ash is released as waste from the boiler. By using biomass boilers instead of coal boilers, you reduce the carbon emissions by up to 10.8 percent every year. When you replace a modern combi boiler, you reduce carbon emissions by up to 2.6 percent every year.
Different Fuels for Biomass Boilers
Wood Chips: Wood chips are ideal when you need a more affordable biomass option. However, the wood chips are larger than pellets, making them more challenging to store. Again, boilers that burn these chips need more frequent maintenance routines.
Wood Logs: Wood logs are huge. You can choose a biomass boiler that uses wood if you have free supply of wood. However, you have to manually feed the wood into the burner, which makes your work more challenging.
Wood Pellets: These are the easiest to use and the smallest of these three fuels. Pellets are compressed shavings and sawdust from wood. The main advantage of these is that biomass boilers can automatically feed them into the boiler from the storage room. When buying wood pellets, you need to understand the size of the pellets, moisture content, and the shape that your boiler requires.
Why Use Biomass Instead of Gas Boilers?
There are a number of advantages to burning wood instead of fossil fuels.
Below are some of these advantages:
- Carbon Neutral – Achieving net-zero carbon emissions takes small efforts from different fronts. Biomass boilers can help reduce these emissions. Plants release carbon when they die even when they are not combusted for fuel. When you burn them for fuel, the only carbon that goes to the atmosphere is the carbon that the plant absorbed when growing – an amount it would have released anyway.
- Highly Efficient – Biomass boilers convert up to 90 percent of the fuel to energy. This is the same level that conventional gas and oil burners give, but biomass boilers come at a more affordable price.
- Inexpensive Fuel – People living near areas with wood will find wood chips, logs, and pellets cheap to acquire – sometimes even for free. This way, you reduce your utility bills by a huge margin.
- Receive Incentives from the Government – The Government, through the Renewable Heat Incentive, gives payments to homeowners who install biomass boilers. You will receive the payments four times a year for up to seven years.
When Biomass Boilers May Not Be a Good Option
High Initial Cost of Installation – You will need between £4,000 and £21,000 to install biomass boilers, depending on the type or size of boiler you choose. Although the running cost will be lower than that of gas boilers, most homeowners may not have enough money to install the boilers.
Space Intensive – Unlike gas boilers that only need a gas cylinder, biomass boilers need a small room where you can store the pellets, chips, or logs. This space need to be near your main house, especially when you use a pellet feeder to automatically run the biomass boiler.
You May Have to Cut Down a Tree – Although you can use tree prunes, trees that die, sawdust, and other waste products from trees and plants, sometimes you may have to cut down a tree. If everyone is to adopt the system, so many trees will be cut. To make the boiler as carbon neutral as possible, homeowners need to plant a tree for each tree they fell. Trees take a long time to grow, and it is advisable that only trees that are near the end of their life cycle are cut down.
When you burn wood, it releases smoke, which is not good for the environment as well as for our health. Modern boilers have a buffer storage that ensures the emissions from the boiler are minimal.
What Will It Cost to Install a Biomass Boiler?
Biomass boilers can be manual or automatic. The manually-fed boilers cost between £4,000 and £10,000, depending on the size and the design. While these are affordable for many households, you have to manually feed the pellets into the boiler every day. If this is an inconvenience you are willing to take, then you can install a manual boiler.
Automatically-fed boilers are more costly and can go up to £21,000. These boilers will save you the hustle of feeding the pellets manually. The cost of biomass boilers is high, considering that you only need about £2,000 to install a gas boiler.
The upfront costs might scare you, but running the biomass system will save you money in the long run. If you need to save money over a long period, you can go for a biomass boiler. Wood chips costs about 2.90 pence per kWh while pellets cost about 5.99 pence per kWh. This is in comparison to gas, which costs 4.17 pence, oil at 4.81 pence, LPG at 7.19 pence, and electricity at 16.36 pence per kWh.
With biomass fuels, the cost does not fluctuate that much from one year to the next. This is unlike the price of gas that rises by up to 10 percent every year. With biomass fuels, you will need to buy the fuel in bulk every year or twice a year.
You may want to check the price of pellets and chips per tonne to see which is more cost-effective. Wood chips are more affordable than pellets. While wood chips cost about £59 a tonne, wood pellets cost about £245 a tonne and wood logs cost about £99 a tonne. Wood logs can be the most cost-effective if you live near a forest where there is free access to logs.
Renewable Heat Incentive
The Renewable Heat Incentive (RHI) rewards people who heat their homes through renewable energy, such as biomass. Once you install biomass (or any other form of renewable energy for heating your home), you receive quarterly payments that run up to seven years. Other sources of renewable energy that benefit from RHI payments include:
You will receive payment for every kilowatt-hour your system produces. Households that produce more usable energy from biomass boilers will receive more payment. The payments received for each renewable heat source are different and are reviewed four times a year.
Currently, biomass received the lowest tariff per kilowatt-hour produced. You will get 6.97 pence for every kilowatt-hour produced in your home with biomass. Other sources offer more money at 10.85 pence per kWh for air source heat pump, 21.16 for ground source heat pump, and 21.36 for solar thermal.
If you install your biomass between now and 2022, you will benefit from RHI. After that, the Clean Heat Grant will take over. The Clean Heat Grant will offer households with renewable sources of energy up to £4,000.
Installing the Biomass Boiler System
Unlike gas boilers, a biomass boiler takes so much space. You need a separate room to install the biomass boiler and store the wood pellets or chips. Here are some of the components of the boiler system:
- Buffer Tank – Also known as the accumulation tank, the buffer tank stores hot water and acts as a heat storage. This storage can then release the heat to the home later. Other heating systems at home can switch on and off with ease and within seconds. However, the biomass system has to burn the pellets or chips, and this is why a buffer tank is necessary.
- Fuel Storage – The fuel storage is a container, a large one, that holds the pellets and chips. The container will be different from one biomass boiler to the next, depending on whether the system is automatically-fed or manually-fed.
- Flue Pipe – A flue pipe directs waste gases out of the home and into the chimney, which then releases that into the atmosphere. If the biomass boiler is located away from the chimney, the flue pipe can direct these gases outside the home.
- Expansion Vessel – This is a section of the system with air and water to balance the pressure within the system.
- Hot Water Cylinder – Once the water is heated, it needs to be stored within a storage cylinder awaiting use. This cylinder then connects to the kitchen faucet or the bathroom and other areas that need hot water.
Biomass boilers can be installed in a garage. If there is no space in your garage, you might need a room designed for the biomass system. However, if you have to heat the water in a room away from the main house, the pipework can cost a lot for homeowners.
Who Can Benefit from a Biomass Boiler?
If you are looking to reduce your carbon footprint, a biomass boiler can be a great choice for you. If you have the space, and you can meet the upfront costs, then biomass boilers can be a great choice for you. There are people who believe that burning wood is an archaic practice, but it is more efficient and more sustainable than burning fossil fuels. It is also an inexpensive way to heat a home and heat water at home.
Before you consider the installation of a biomass boiler, note that you will need the following:
- A large cylinder to store the water you will need for domestic use. These systems do not switch on and off as fast as gas systems do and that is why you need to store the water you need.
- Sufficient insulation on the walls, floor, and loft to ensure your home doesn’t lose the heat from the biomass heater.
- A place to dispose off ash that comes from the biomass boiler. If you have a manual boiler, you will need to remove the ash and dispose it off. An automatic boiler will automatically dispose off the ash from the system.
- A huge heat delivery system, seeing that the temperature of the water from a biomass boiler will be lower than that from a gas boiler. Buffer tanks come in handy in storing the heat to release it later to the home.
- Enough space to store the pellets and chips and install all the components of the biomass boiler system.
If you are already connected to the gas network, you might feel as if it is cheaper to continue using a gas boiler. After all, natural gas offers a clean way to heat a home without producing fumes. However, the supply of natural gas gets low from year to year and leads to an increase in natural gas prices by up to 10 percent each year.
If your home meets all the qualities above, you can install a biomass boiler and start cutting down your carbon emissions. In the long run, the biomass boiler helps you receive the huge upfront costs.
Biomass Boiler Maintenance
If you have a manual biomass boiler, you will need to load it manually and clean it every week. Such systems require frequent check-up and maintenance to ensure they are in good working condition. If you have an automatically-fed biomass boiler, you will not need to spend so much time feeding it manually or cleaning it every week. After the system burns wood pellets, it releases ashes automatically.
After installation, most systems do not need extensive work done on them. Instead, the systems have a high temperature output and most radiator systems will be sufficient to heat the rooms. If you already have radiators for other heating systems, they will be enough to heat your rooms.
Picking the Right Biomass Boiler
When shopping for a biomass boiler, consider the biomass material available in your area. If you have access to free wood logs, you might need to pick a boiler that burns logs. These logs are challenging to carry and store, but they are ideal if you can get them free.
If you do not have access to logs, consider which is the most cost-effective between pellets and chips in your area. From there, consider the size and shape of the room you want to heat. The bigger the house and the rooms, the bigger the size of the biomass boiler you need to install.
You should also consider the nature and effectiveness of the insulation you already have and the heating requirements of different rooms in your home. You might need to review the insulation because picking a larger biomass boiler means you have so much energy going to waste.
You can have air or hydro heating from a biomass stove. In air heating, the stove will heat the room you place it in. In hydro heating, the stove carries hot water through the plumbing system and heats the entire house.
Renewable Energy Training
VIVA Training Academy is committed to renewable training for new and experienced gas engineers who want to expand their service to meet the Net Zero target by 2050. Our renewable courses are designed for existing building services installers, providing a relatively easy way to gain the necessary qualifications to future-proof your business.
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