Delivering the benefits of biomass boilers

Renewable energy, RenEnergy, biomass
Biomass boilers can meet the entire demand for heating and hot water, or they can be designed with backup for added security of supply

With 44% of the UK’s energy demand being due to space heating, renewable heat technologies such as biomass boilers will have a significant role to play in reducing the UK’s carbon emissions. Damian Baker discusses the feasibility considerations for biomass projects and the wide-ranging benefits of biomass systems.

Under the European Commission’s Renewable Energy Directive, the UK has a binding target to source 15% of our overall energy from renewable resources by 2020. At present 44% of the UK’s energy demand comes from space heating, meaning that renewable heat technologies such as biomass boilers will have a significant role to play if we are to meet the objectives set.

Biomass is derived from recent biological origin and comes in a variety of forms, including woodchip, pellets and logs. These fuels can be burned in a biomass boiler or a stove to produce useful energy for space and hot water heating. Biomass is a versatile fuel which can be used for different scales, from commercial projects to everyday households.

A well designed biomass system can meet the entire demand for heating and hot water demand and can be designed with back up for added security of supply. A biomass system will significantly improve carbon emissions due to the sustainability of the fuel used. The low cost of this fuel, relative to oil or gas, will result in significantly lower bills.

Commercial biomass systems are eligible for the Renewable Heat Incentive (RHI) which can provide a highly effective additional revenue stream, reducing the payback time and enhancing the return on investment. The RHI scheme pays those installing renewable heat sources such as biomass, for the heat they generate. The RHI payments are guaranteed for 20 years and are currently only available to commercial-scale heat users. Rates vary depending on the scale and are currently 8.3 p/kWh for installations up to 200 kW and 5.1 p/kWh for installations from 200 to 1000 kW.

Biomass systems can help to meet Building Regulations, Code for Sustainable Homes Levels 3, 4 and above in residential builds and BREEAM requirements for commercial builds.

As is the case with all renewable heat technologies a large amount of time needs to be dedicated to the design and feasibility phase as there are a wide range of factors to consider. The major points to look at in the initial stages of a project are discussed below.

However small the boiler, fuel storage will be required unless you are prepared for daily deliveries. The storage area will need to be dry and have sufficient access for an articulated lorry.

Among appropriate fuels for biomass boilers are wood chips and wood pellets.

Biomass boilers are larger than traditional fossil-fuel boilers. They often require buffer tanks and will need adequate space around the components for maintenance. The existing plant room/plant room design will need to be sized accordingly.

When choosing which fuel to choose there are a number of factors to consider.

• The specification of the boiler. Most boilers will only burn certain types and quality of fuel.

• The nearest fuel supplier and the type of fuel they supply. Finding a supplier close to the site of the boiler is critical, high transportation costs will impact on the financial viability of any project.

• Will the boiler be manually or automatically fed?

• How many deliveries will be required in a month?

In addition there are standards which must be adhered to because they ensure the correct fuel is being used for the boiler and also whether or not the fuel is RHI compliant. The standard of a fuel is shown using a CEN code; there are over 30 codes which, broadly speaking, describe the following aspects of the fuel.

• Origin.

• Moisture content.

• Ash content.

• Calorific value.

• Species of wood.

• Fuel dimensions (different fuel types are measured in different ways).

• Sampling requirements.

Biomass is a highly efficient method of space heating, with numerous benefits. However, the quality of system design and quality of installation is absolutely critical to the performance of the system, so appropriate time needs to be devoted to assessing the feasibility and design.

Damian Baker is managing director of RenEnergy.

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