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n March 2011 the UK Government announced the biggest shake up of the heating industry in decades. The Renewable Heat Incentive (RHI) has been designed by the Department of Energy & Climate Change (DECC) to revolutionise the way buildings are heated and will mean biomass heating is financially the preferred choice in all commercial and public buildings. It is the first financial support scheme for renewable heat in the world and comes at a time when most public sector organisations are in vital need of additional funds and cost efficiencies.

THE TRIPLE BENEFIT Together with the income from the RHI, heat users benefit from: • Carbon savings achieved as they offset the Carbon Reduction Commitment levy

• Reduced use of counterfactual fuel (this is usually the incumbent fossil fuel such as gas, oil or LPG). This triple benefit makes biomass the

UK’s most financially attractive fuel. The tariffs have been set to achieve a 12% return on the additional cost of using biomass heating as an alternative to gas, therefore projects displacing oil or LPG can achieve even greater returns. The funding is expected to stimulate £4.5 billion of capital investment up to 2020, which equates to an estimated 13,000 installations of renewable heating systems in the industrial sector as well as 110,000 installations in the commercial and public sector.


Over the last decade building- integrated renewable energy has mainly been installed in new developments to meet planning requirements such as the ‘Merton Rule’ (a percentage renewable energy requirement for new developments). This policy and various grant programmes have enabled the

biomass heating industry to flourish and quality fuel supply networks have developed. However, the Merton Rule did not include any retribution if theoretical carbon savings were not achieved. This meant the construction industry could continue to drive down capital costs and some never delivered the carbon savings promised. The RHI completely changes this with payments made on a quarterly metered heat basis – the whole life cost is now critical to a projects success.


The RHI encourages the long-term delivery of renewable heating in existing buildings, so to fully realise the financial value of your asset you need to analyse the impact it is having on your fuel consumption. To do this calculation it is essential to understand the difference between fuel going into a fossil fuel boiler and the actual heat delivered. You also need to consider the efficiency of the gas boiler and only then can heat tariffs in terms of pence per kilowatt hour (p/kWh) be compared on a like for like basis. Biomass tariffs and the RHI are quoted in terms of delivered heat, already taking into account calorific value and boiler efficiency. This key difference between the tariffs quoted on fuel bills and actual delivered heat is often misinterpreted in favour of fossil fuels.


The next vital step is deciding if you have space for all the equipment. Biomass heating systems are bigger than their fossil fuel equivalents and the footprint depends on the size of the heating demand, the type of biomass fuel and several other site specifics described below.

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Biomass boilers can be fuelled by either wood pellets or wood chip. Wood chips are lower cost per kWh of heat delivered than wood pellets, but require greater volumes due to its lower calorific value. Wood chip also has a tendency to form ‘chip bridges’ over equipment and require cajoling and agitating into the boiler through the use of rotary agitators, walking floor mechanisms


or hydraulic rams. Chip

designs also need an underground fuel store or even a transportable fuel store called a hook bin, otherwise it can become difficult and expensive to re-fuel. Pellets are more expensive per kWh of heat delivered, but have flowing properties and a higher energy density. This means the fuel handling equipment is simpler and has a smaller footprint than the chip equivalent. The fuel store can also be refilled by blowing pellets from a specialised, but widely available, vehicle. In general, we favour wood chip for new developments when we can more easily influence the design of the building to favour wood chip and we encourage pellet for retrofit to existing buildings (where there are usually greater space and design constraints and to minimise significant building modifications). As well as the large boiler and associated fuel store, some sites may also need an accumulator tank. This technology can give many benefits including stopping the boiler inefficiently low load cycling (boiler turning on and off rapidly when there is small heat load). An accumulator tank can also meet a site peak heating demand at a particular time of day and ensure a constant supply of instantaneous hot water. The size and

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