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.
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?
- Do you have any planning exclusions, e.g. vehicle movements, visual intrusion, noise restrictions or limitations on chimney heights?
- Is there enough space for lorries to regularly deliver the fuel?
- Do you have sufficient space for the larger boiler and a fuel store?
- Do you have the capital to invest in such a system? Biomass energy solutions tend to have higher capital costs than fossil fuel-fired systems, but can attract financial support schemes.
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.
- Return on your investment in three years if the biomass replaces electric, fuel oil or LPG.
- Net carbon emissions per kilowatt hour (kWh) are much lower than energy sources from fossil fuels. E.g. The carbon emissions for woodchip are 10-23kg of CO2 per megawatt hour (MWh), compared to 263-302kgCO2/MWh for natural gas.
- Biomass systems are relatively easy to convert to other fuels and offer greater flexibility for an uncertain energy future.
- In some regions biomass are considered waste products; burning them for energy can reduce disposal costs and free up landfill sites.
- Biomass plant will typically cost two to five times as much as an equivalently sized fossil fuel system.
- The payback won’t be quite as fast if you’re replacing natural gas.
- Larger size boiler and the storage and handling equipment needed.
- Burning biomass usually takes more operator attention then burning conventional fuels.
- In contrast to other fuels, biomass fuel is variable in quality. It may require more vigilance and effort from the owner to ensure the desired fuel quality.