BBC News 13 Apr 09;
Biomass power could become one of the worst emitters of greenhouse gases, the Environment Agency (EA) has warned.
Ploughing up pasture to plant energy crops could produce more CO2 by 2030 than burning fossil fuels, it said.
The EA's study of biomass fuels also found waste wood and MDF produced the lowest emissions, while willow, poplar and oil seed rape made the highest.
The agency has called on the government to force biomass companies to report all greenhouse gas emissions.
Wood-burning stoves, boilers and even power stations are seen by many as critical to Britain's renewable energy targets.
Biomass is considered low carbon as long as what is burnt is replaced by new growth, and harvesting and transport do not use too much fuel.
'Role to play'
But the EA's report Biomass: Carbon Sink or Carbon Sinner found that the greenhouse gas emission savings from such fuels were highly variable.
At its best, biomass could produce as little as 7kg of CO2 per kilowatt hour - 98% less than coal, saving around two million tonnes of CO2 every year.
However, the study also found that in some cases overall emissions could be higher than those of fossil fuels.
This was particularly true where energy crops were planted on permanent grassland, it said.
Tony Grayling, head of climate change and sustainable development at the Environment Agency, said biomass could play a role in helping the UK meet its renewable energy targets.
But he argued the credibility of biomass rested on tough sustainability criteria and called on biomass projects to combine heat and power production.
"Biomass is a limited resource, and we must make sure it is not wasted on inefficient generators that do not take advantage of the emissions savings to be made from combined heat and power," he said.
"By 2030, biomass fuels will need to be produced using good practice simply to keep up with the average carbon intensity of the electricity grid."
