For businesses that produce significant volumes of woodwaste, renewable energy offers advantanges through reduced costs and tax breaks. Many different types of businesses are affected, including sawmills, joinery companies and furniture manufacturers, as they either use, or have the potential to use, wood combustion plants.

Currently any wood combustion plant of more than 0.4MW requires local authority authorisation and is controlled under process guidance note PG1/12. It is believed around 300 furniture manufacturers alone are affected – and the true figure could be double that, not to mention joinery firms as well.

Authorised combustion plant must comply with the requirements of the guidance note, which is being revised. The Department for Environment, Food and Rural Affairs has proposed a significant tightening of the legislation, which would threaten to close 70% of existing boiler plants. This would have a major impact on many small- to medium-sized enterprises.

Costly replacements

Replacement of 1.3-3MW plant would cost £250,000-500,000 per company – which equates to a figure of perhaps £50-100m for the sector as a whole. Consequently, many furniture sites are likely to shut their existing boiler plants and landfill timber waste.

Gaps in our knowledge of the scale and state of authorised wood combustion prohibit an informed decision on the degree to which tightened emission limits may be justified. In addition, there are large variations in operational practices and the subsequent levels of emissions generated by similar plants.

Research by the British Furniture Manufacturers‘ trade association is study the impact of the changes.

The project is being led by Alistair Bromhead, an experienced environmental consultant, and will lead to a best practice document containing benchmarking data on boiler performance to allow manufacturers

to compare their own practices/emissions with those of the best. Best practice advice would be provided on system optimisation, with the provision of guidance on the size/costs/paybacks of different systems.

The latter would show companies the calculations needed to evaluate the viability of a new wood combustion system.

What is PG1/12?

PG1/12 is the process guidance note that applies to any wood-burning boiler rated at 0.4MW or above – equivalent to a feed rate of 70-90kg/hour of timber.

Any companies operating plant at or above this must be authorised by their local authority and must comply with the process guidance note. This sets a number of emission limits and operational requirements, the most significant of which relate to limits on emissions of particulate and carbon monoxide. The limit for the latter is currently set on a site specific basis, but is usually in the range of 400-1000mg/m3 for boiler plant pre-1995. The proposed revision will bring this down to just 150mg/m3. Upgrading is typically not a realistic option so the majority of older boiler plants would have to close.

It is unlikely that many would be able to afford a replacement boiler so many companies might be tempted to send woodwaste to landfill – leading to a much greater environmental impact than that caused by their current boilers. Furthermore, in the case of furniture sites, this will provide another incentive to do away with woodworking altogether and purely assemble imported items.

One of the key aims of the British Furniture Manufacturers’ project is to gather information on exactly how many plants would be forced to close their boilers and their probable strategy in order to convince those responsible for the review of the guidance note that a tightening of emission limits will not lead to a simple switch to modern equipment and a much cleaner environment.