Are biomass boilers worth it?

    April 25, 2014

Biomass boilers offer a great heating solution that really does pay for itself and then some. Combined with the great savings to be made with biomass fuels and the government’s domestic Renewable Heat Incentive (RHI), it really does make sense to look at biomass for your home.

Biomass boiler – a Straight Alternative to Oil or LPG

For those off-grid properties, biomass is a much cheaper fuel to run your heating on when compared to heating oil or Calor gas. Even when compared to heat pumps, the closest renewable competition, biomass generally wins.

While you can install a heat pump (air source or ground source), there is a difference when compared to biomass (heat pumps operate at much lower temperatures), which will mean that you will have to slightly change how you distribute your heat – by increasing the size of your radiators and / or consider installing underfloor insulation (the latter is not mandatory).

Biomass Boiler

Therefore the big advantage over heat pumps is that you can install a biomass boiler with your existing radiators and hot water system as they operate at high temperature and do not require as big an output to provide the same volume of useful heat.

Even if you are on grid, you can still benefit from a biomass boiler – as long as you have the space and are not in a clean air zone (it is very restrictive to use in urban areas of London). Even comparing the cost of gas to biomass fuel can be favourable, especially when you factor in the RHI payments.

Insulation not as important

As mentioned, heat pumps are the other way to get RHI-funded heating, but because they produce lower grade heat, they don’t tend to work well with a traditional radiator system. In these cases, you will probably need to install additional insulation to bring the heat demand right down to be worth it.  Insulation is cost effective if you have a cavity wall property, but if it is of solid wall construction then you will need to consider getting expensive insulation, and the costs will start to add up.

Biomass has the added advantage of not needing a super insulated house – although we advise on always trying to get the best possible insulation. Where heat pumps rely on high quality insulation to function effectively, costing thousands of pounds, biomass will work well in any home, with just your basic loft and cavity wall insulation. In fact, you will actually get more money as part of the RHI when your property requires more heat to warm it – but loft and cavity, if recommended on the Energy Performance Certificate (EPC), must be installed!

How much can I earn on the RHI for Biomass?

The RHI will pay you 12.2p/kWh and the amount you get will depend on the heat demand on your EPC. A typical property with a heat demand of about 20,000 kWh will receive more than £2,400 a year; or £17,500 over a 7 year period. That’s a lot of money and will cover the cost of the installation well before the end of the life of the boiler.

To demonstrate how the RHI payments can work with real properties out there, we have selected a range of properties we have assessed and have summarised the typical heat demands and therefore the expected payments.

House type Typical Heat Demand RHI (7 Years)
Terraced House (D Rated) 10,000kWh £8,400
Semi Detached 3 Bed (D Rated) 20,000kWh £16,800
130m2 Detached 4 Bed (E Rated) 25,000kWh £21,000
300m2 Modern Detached House (B Rated) 20,000kWh £16,800
300m2 Detached House(E Rated) 50,000kWh £42,000

In reality, to see how much your property will get, you need to look at the last page of your EPC. Look at the heat demand combined with the water heating requirements then multiply by the tariff (12.2p/kWh). Generally speaking, smaller terraced properties are unlikely to have the space required for one of these boilers, but for larger properties, the returns are very generous.

How do I claim for the RHI payments?

Getting the RHI is really easy. You will need the installation to be done by an MCS accredited installer (you can find an MCS installer here), and a Green Deal Assessment carried out on the property. It is just worth noting that a Green Deal Assessment will produce for you an EPC and the Occupancy Assessment – so you will then be able to see the heat demand on the certificate that is produced.

Please note: if the assessment recommends loft or cavity wall insulation, you will need to get these installed; otherwise, it is just a case of making the application if you have those in place already (i.e. the EPC will not have these as recommendations).

Can we help on the RHI application process for the biomass boiler?

Absolutely! As a Green Deal Advisory Organisation and experienced energy consultants we can deliver both the Green Deal Assessment (EPC & Occupancy Assessment) and help on putting you on the right track with the RHI application.

Installing a Biomass Boiler

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      Biomass Energy


    What is biomass energy?

    Biomass is biological material derived from living – or recently living – organisms. In the context of biomass energy, this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material. The carbon used to construct biomass is absorbed from the atmosphere as carbon dioxide (CO2) by plant life, using energy from the sun. Plants may subsequently be eaten by animals and thus converted into animal biomass, but the primary absorption is performed by plants. This is however the basis of biomass energy, which in essence is the capture of the sun’s energy that is stored in living organisms.h

    Fossil fuels on the other hand offer high energy density, but making use of that energy involves burning the fuel, with the oxidation of the carbon to carbon dioxide and burning the hydrogen to produce water (vapour). Unless these emissions are captured and stored (see CCS), then these combustion products are usually released into the atmosphere, returning carbon sequestered millions of years ago and thus contributing to increased atmospheric concentrations.

    How is biomass energy different to fossil fuel energy?

    The vital difference between biomass and fossil fuels is one of time scale. Biomass takes carbon out of the atmosphere while it is growing, and returns it back to the atmosphere as it is burned. If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. Forms of replenishment are as follows: (1) woodland or arboriculture management or (2) coppicing or (3) as part of a continuous programme of replanting with any new growth taking up CO2 from the atmosphere. This maintains a closed carbon cycle with no net increase in atmospheric CO2 levels, which means the release into the atmosphere by combustion is absorbed by new growth.

    Biomass energy for your business

    The main difference between biomass boilers and fossil fuel-fired systems is that biomass energy systems are larger. The heating system itself works in a very similar way to a conventional system. A biomass energy system typically consists of the following: a boiler, control system, mechanical system (pipes, valves, flues etc.), infrastructure to receive and store fuel and infrastructure to transfer it to the main boiler unit.

    Heat energy

    Biomass energy is extracted using biomass fuel, which is burnt in a combustion chamber and the heat is then used to heat water. This hot water then heats the building through a normal hot water heating system. Steam can also be used in industrial processes where appropriate, and hot air is sometimes used for space heating. However unlike electricity generation, which is subsidised by the ROCs, the Renewable Heat Incentive (RHI) is not yet in place to help subsidise district renewable heating solutions.


    For generating electricity, the steam produced can be used to power turbines, which then runs an electric generator and creates power. As biomass energy is part of the renewable fuel grouping for electricity generation, users can now also benefit from Renewables Obligation Certificates (ROCs), which are received at a prescribed level for every MWh of power generated.

    Biomass energy plants can vary from being small, manually-fed systems with basic controls, to fully automatic systems with advanced controls and remote monitoring. You should always consider fuel availability and consistency, as well as storage and handling, during the design, implementation and operation stages. Of all possible renewable heating solutions, biomass energy has the potential to deliver some of the most significant and cost-effective carbon savings, particularly for commercial and industrial applications. In addition to carbon savings, biomass energy also offers significant benefits for users, including operational fuel cost savings and reduced fuel price volatility.

    A biomass energy plant in a small town or village for example can stimulate local economic activity by creating fuel supply chains and making good use of resources that would otherwise be treated as waste and sent to landfill.

    ROCs for biomass energy electricity generation

    As mentioned in the previous section if you have a biomass energy system, then depending on the power output, the system can be eligible for ROCs if the plant generates electricity. The precise number of ROCs depends upon the biomass generation type. According to the Department for Energy and Climate Change (DECC), if the electricity generated is partly from fossil fuel and partly from biomass, then it is entitled to 0.5 ROCs per MWh. Dedicated biomass generation is applicable for 1.5 ROCs per MWh. The use of energy crops mixed with fossil fuel or CHP (cogeneration) process entitles the generator from 1 ROC to 2 ROCs depending on the mixture. Pure energy crop electricity entitles the generator to 2 ROCs per MWh.

    How suitable is biomass energy for my business?

    Before commissioning a detailed feasibility study on biomass energy, ask yourself the following questions:

    Sourcing fuel for biomass energy

    The three most common types of commercially available biomass fuels are wood-based (logs, woodchips and pellets). However, other fuels such as straw are also used as part of the biomass energy grouping.

    Biomass energy fuel supply needs to be sustainable in principle, so that the renewable credentials are maximised. You should diversify the scope by purchasing biomass fuel from many suppliers, and you can make long-term agreements to secure a fixed price into the future. If you can source the fuel locally then you will also have more control over the security of your supply.  This will also increase your on-site storage giving you that buffer against short-term supply problems.

    It is common practice to undersize the biomass boiler and to include a thermal store (large hot water tank). This helps to smooth the heat demand profile and ensures that the biomass boiler runs for long hours at high load. An auxiliary fossil fuel fired boiler is then used to cope with peak loads. This multi-fuel strategy gives greater security against fuel problems too, but is not as good for the environment.

    Industry policy trends for Biomass Energy

    The take up of biomass energy in electricity generation in the UK, and its long-term outlook, is mixed. For example, companies like Drax Power and E.ON have moved away from their initial enthusiasm for expansion, which has been due to uncertainties, driven by the outcome of the Renewables Obligation (RO) review. However, the government has signalled on more than one occasion that the banding will expand, so as to further support CHP initiatives. For this reason the industry is waiting for more details to emerge on the Renewable Heat Incentive – due to launch later in 2012 / early 2013.




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