Renewables / Alternative Energy 04 Sep 2014

A guide to biomass boilers for farms

Biomass

Biomass boilers provide a sustainable heating solution for farmers looking to reduce their heating costs, explains Anna Wakefield, Marketing Manager for Grant UK.

There is no doubt that the cost of heating rural properties remains a major financial issue for farmers. With energy bills so high and in the anticipation of further increases in the price of fossil fuels, looking for alternative ways to reduce energy costs in off-gas areas is an attractive idea.

Biomass boilers, and in particular those that burn wood pellets, provide a practical and efficient heating solution for properties in rural areas. They achieve significant energy cost savings and also enable farmers to access to the Renewable Heat Incentive (RHI), a government initiative that financially rewards domestic and commercial users for generating and using renewable energy to heat their homes or premises.  For instance, on a quarterly basis (for 20 years from the date of installation, but paid over a 7 year period), the Domestic RHI will currently pay a tariff of 12.2p per kWh for biomass boilers, whereas the Commercial RHI tariff will pay up to 7.6p per kWh (paid over a 20 year period). These rates are subject to change.

Grant UK has a range of condensing wood pellet boilers that are suitable for both domestic and commercial applications.  They are MCS approved, so eligible for the RHI and are also currently the most efficient wood pellet boilers in the UK, as stated on the Building Energy Performance Assessment website.

Accessing the RHI, along with the energy saving costs and high efficiency ratings achieved by these boilers, means that an investment in biomass is a perfect alternative to fossil fuels for farmers – but how does biomass boiler technology work?

In the case of wood pellet boilers, they have a similar output to traditional fossil-fuelled appliances and require a large hopper to store fuel and so are usually installed in a garage, store or outhouse. Wood pellet boilers use advanced controls, which regulate the amount of fuel being fed to the burner to match the heat demand of the boiler. The fuel is fed to the burner via an auger connected to the adjacent pellet hopper. This can, in turn, be automatically supplied from a bulk pellet store, which can vary in size.

On start up, the auger feeds the wood pellets from the hopper into the burner where they are lit by an ignition element. The burner output modulates to achieve the set temperature by controlling the feed rate of pellets. The fan in the burner propels hot gas generated from the fuel into the product’s primary heat exchanger. The heat energy is then transferred to the water circulating around the radiators or underfloor pipework of the heating system.

While many modern pellet boilers will lose up to 20% of the energy produced through waste gases exhausted by the flue system, appliances such as the Grant Spira condensing range have a secondary heat exchanger, designed to capture some of this lost heat energy.

When looking for a suitable site to install a wood pellet boiler, it is important to ensure you have enough space for the appliance and storage of the fuel. A bulk storage system can be used for greater pellet capacity and if auger fed, needs to be sited close to the boiler.  Alternatively, for installations where an auger fed hopper arrangement is unsuitable due to space restrictions, a vacuum system can be used, allowing a distance of up to 20m between the boiler and pellet store.

The room, in which the boiler is installed, also requires sufficient ventilation to ensure an adequate air supply.  It allows the appliance and flue to operate safely and efficiently and can be easily provided by a correctly sized permanently open air vent.

Wood pellets are available from a number of manufacturers and specialist suppliers in the UK. They can be bought in bags of varying sizes or delivered in bulk by tanker, which is the most cost effective option.

Wood pellet boilers produce ash and do require cleaning and maintenance, however the very best wood pellet boilers, such as the Spira, have a number of self-cleaning function which, when using EN Plus A1 grade pellets with low ash content, reduces the need for regular maintenance.

For farmers with homes and buildings to heat, wood pellet boilers provide a practical, efficient and cost saving alternative to fossil fuels. For more details call 01380 736920 or visit www.grantuk.com.

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