Biomass builds a solid reputation

wood chips
The typical cost of wood chip as a fuel is less than 2 p/kWh.
Dr Robin Cotton explains how biomass is providing heating solutions for large-scale applications such as district-heating systems and outlines its future development prospects in the UK.As fossil fuel prices continue to rise there is a growing understanding of the benefits that biomass can deliver, both by significantly reducing energy costs and cutting carbon-dioxide emissions. Wood fuel is one of the most important sources of sustainable energy in the UK, and Government grants to help with the costs of biomass boilers are simplifying entry to the market for new customers. Policy drivers A number of policy drivers are also encouraging end users to use wood for heating to reduce carbon dioxide emissions. These include the national Climate Change Levy, the European emissions trading scheme, and local legislation — in particular the so-called ‘Merton Rule’ under which a number of local authorities now require 10% or more of renewable energy generated on site for all large new building developments. Currently, buildings are responsible for around half of the UK’s emissions of carbon dioxide in the UK. For building developments with is a significant demand for space heating or domestic hot water, wood-fired boilers offer considerable reductions in carbon-dioxide emissions — generally greater than any other available on-site renewable technology. Recent advances in boiler technology also makes using biomass in towns and cities a viable prospect. Wood is a complex organic material, so emissions must be considered. Although the current Building Regulations (Part L) give a calculated value of for carbon-dioxide emissions from wood of 0.025 kg/kWh, about one-eighth that of natural gas, locally produced wood chippings are likely to have significantly lower carbon intensity. Potentially hazardous emissions from biomass combustion systems such as oxides of nitrogen and sulphur have been reduced to very low levels. Control strategies such as lambda control and exhaust-gas recycling have greatly improved air quality. The same applies to abatement technology such as cyclone particle separators. Clean Air Act The Clean Air Act of 1993 provides that no heating appliance, regardless of fuel, may emit smoke in areas designated as smoke-control areas without undergoing strict testing and certification to a British Standard protocol. Installing a biomass boiler in a smoke-control area without the relevant testing having been undertaken and the necessary exemptions having been granted means the operator runs the risk of prosecution under the act. Unlike many biomass boilers, all Binder boilers, for which Wood Energy is the sole distributor and installer, from 15 to 1200 kW have been tested and certified to this British Standard. Binder boilers have been developed over many years to achieve outstanding performance in terms of efficiencies and emissions. Although the substantial reduction of carbon emissions has been the driver for installing biomass boilers to date, many organisations are also concluding that higher installation cost compared with gas-fired system is an acceptable trade-off for the long-term fuel-price stability that wood fuel offers. Typical costs of wood chip are currently less than 2 p/kWh for compared with about 3 to 4 kWh for gas and oil. The payback period will vary according to the size of the system, the local fuel cost and load factor. However, medium- and large-scale projects typically achieve payback periods of between four and 10 years — before any grant support is taken into consideration. The technology is up and running in schools, prisons, leisure centres, hospitals, plant nurseries, retail parks, offices and district-heating housing projects across the UK and Ireland. Installations Wood Energy Ltd is currently supplying and installing the largest district-heating system in the south-east of England, based around an 840 kW boiler system. The biomass boiler will be complemented by a gas-fired back-up system and will service around 220 homes in a development near Redhill station. Wood Energy Ltd also recently commissioned a 1.2 MW wood boiler at the Charlestown shopping centre in Finglas, Dublin. The boiler provides space and water heating for 284 residential apartments and a variety of retail outlets. So long as delivery of wood fuel can be managed and appropriate storage arranged, there is no barrier to biomass heating in built-up locations. Another influence on the popularity of wood fuel has come direct from customers in the private sector who want to see companies coming up with green solutions. FTSE 100 companies are under pressure to announce their CSR (corporate and social responsibility) or sustainability reports, and being able to display a commitment to renewable energy has proved popular. Being able to deliver a building with strong green credentials has been a major factor in persuading public- and private-sector clients to explore biomass. Reliable operation Boilers have become increasingly sophisticated and include many advanced features to ensure efficient and reliable operation. The latest models can be monitored remotely, allowing installers to fine-tune and watch over customers’ heating systems from their own premises. Potential customers are finding that high specification biomass boilers can satisfy their heating requirements. For a long time continental Europe, without the benefit of North Sea oil and gas, has followed a path of diversification to fulfil its energy needs. Now the UK is discovering the benefits that biomass can deliver, putting the technology firmly on the forward-thinking specifier’s radar. Dr Robin Cotton is managing director of Wood Energy Ltd.
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