Web exclusive posted April 23, 2008 at 1:27 p.m. CST

The United Kingdom has called for more waste wood to be used as fuel. Joan Ruddock, minister for climate change and waste, called failure fully to exploit discarded wood is "a huge potential resource that is being wasted."

The minister's comments were made at the April 9 launch of a new government-commissioned report detailing the sources and quantities of wood waste in the U.K. that could be diverted from landfill and used to produce energy.

Waste Wood as a Biomass Fuel: Market Information Report says about 10 million metric tons (11 million U.S. tons) of wood waste is produced each year in the U.K. from industries such as construction and packaging; most of it ends up in the landfill. "It has been estimated that recovering energy from 2 million tonnes of waste wood could generate 2,600 gigawatt-hours of electricity, saving 1.5 million tons of carbon dioxide equivalent emissions, with greater benefits available by recovering heat as well as power," the report states.

The key to using more waste wood as fuel is building incinerators that comply with tighter restrictions on burning waste so more contaminated wood could be used as fuel, the report says. Older incinerators that don't comply with the so-called Waste Incineration Directive are precluded from burning certain types of material.

Professor Andreas Hornung, a chemical engineer at Aston University in the U.K. and an expert in recovering value from waste materials, welcomes moves to squeeze energy from waste wood. "In my opinion it is a huge opportunity if the market is prepared in the right way," Hornung told Biomass Magazine.

Hornung said there are two principal mechanisms needed to enable the resource to be exploited fully: efficient separation of "clean" wood at collection sites that could be streamed off for burning, and new technologies to extract energy from highly contaminated wood, such as "railway sleepers" – railroad ties – that are steeped in preservatives. Direct incineration of such material would create too much pollution and would require processing to extract contaminants for separate treatment.

Hornung is working on a new pyrolysis system that heats heavily contaminated wood to approximately 450 degrees centigrade (842 degrees Fahrenheit) and the resulting combustible vapors are then "conditioned" by a special process – currently under development and subject to a patent application – to remove any contaminants before the gases are used as feedstock. The remaining solid coke can then be removed and treated for decontamination of any residual pollutants.

If the U.K. does burn more waste wood, Hornung pointed out the importance of ensuring that the public receive clear information about the type of material being processed for energy production. "It is important that no one feels there are toxic compounds coming out of this combustion," he said.