Biomass boilers can deliver large cost and CO₂ savings over fossil fuels, says Gordon Traill, and district heating schemes can mean that fuel cost and CO₂ savings can be magnified.
Biomass district heating is where more than one building is heated by a single biomass boiler, as opposed to a single boiler serving a single property.

The boiler in a district heating scheme is usually connected to a thermal heat store, with which the boiler communicates to maintain a target temperature.

Heated water is then distributed to each individual building through a network of insulated underground pipes.

Within each underground pipe there are flow and return pipes, which typically connect to a heat exchanger at each property. A thermostat then enables the building's occupant to control the temperature of their domestic hot water and space heating through radiators or underfloor heating.

Each building in the district heating scheme can be fitted with a heat meter, which enables their usage to be measured and their heating bills to be calculated.

The combined meter readings will also give the owners of eligible biomass boilers the opportunity to apply for inclusion in the Renewable Heat Incentive and gain payments per kWh of green heat generated from the end of 2011.

Smaller footprint

Biomass district heating has various advantages compared to individual heating systems as the capital cost per building is far lower. A single boiler has a far smaller footprint than several, so far less space is required than with separate boilers.

Situating them in their own dedicated boiler house also frees up space in the main properties. A single boiler saves time in refuelling as just a single delivery is required and there is also a cost and time saving from far less servicing and maintenance per housing unit.

Larger and more advanced combustion units and the simultaneous production of heat for multiple housing units can deliver higher energy efficiencies and better pollution control than several localised boilers.

Biomass boiler district heating schemes have the potential to protect whole communities from rising fossil fuel costs and possible fuel shortages. For example, the UK has only enough gas stored to last around eleven days and forecasts of an even colder winter this year suggest that more than a million oil-reliant families may face price spikes and shortages once again.

As well as significant fuel cost savings, from late 2011, the owners of eligible biomass boilers will have the opportunity to apply for inclusion in the Renewable Heat Incentive (RHI) and gain payments per kWh of green heat generated. These payments and the fuel cost savings can mean a district heating scheme can be not only environmentally, but financially rewarding.

The fuel savings and RHI income can be re-invested by social housing associations to overcome the impact of cuts across the sector following the Comprehensive Spending Review. This can, in turn, help to ease fuel poverty among the most vulnerable by offering cost-effective heating to tenants. The savings and RHI income can enable social housing associations to sustain the provision of other front-line housing services in the face of cuts across the sector.

Biomass can boost fuel savings

Treco has directly installed more than 250 biomass boilers nationally since 2006. One scheme it installed in a new build housing development saw three 100kW biomass boilers provide the heating and hot water for 66 properties, a mix of social housing and private ownership.

Each boiler was installed in a custom-built boiler house. These were dotted around the site. Each property then had its own customer interface unit including a heat meter with a radio link and a heat exchanger for space heating, or two heat exchangers where domestic hot water was also required. The scheme helped the developer deliver against the Code for Sustainable Homes and meet stringent planning requirements.

Biomass district heating schemes can boost fuel cost savings up to 50 per cent compared with fossil fuels across multiple social housing units. These fuel savings and RHI income can be re-invested by housing associations to overcome the impact of widespread cuts across the sector.

• Gordon Traill is managing director of Treco