New technology and an ancient practice of the Amazon Indians could be a potent weapon in the fight against global warming.
Surprise: less oxygen could be just the trick
June 12, 2007
It was used by the people of the Amazon for thousands of years. Now Australian researchers say biochar could reduce atmospheric carbon dioxide - while providing a new source of energy, and boosting farm productivity.
For almost 7000 years Amazonian farmers kept their soils fertile by setting organic waste alight and letting it smoulder under mud or earth, reducing it to a black carbon-rich material.
" Biochar is not unlike charcoal," says Lukas Van Zwieten, a senior research scientist with NSW's Department of Primary Industries.
When organic material is burnt with air it is often reduced to white ash. Trapped carbon goes up into the air as carbon dioxide, hence the greenhouse emission problem at coal-fired power stations.
But if heated while starved of oxygen "it just goes black, like a pizza left too long in the oven", says Van Zwieten. Called pyrolysis, the process leaves up to half the carbon trapped in the char.
At Somersby, on the Central Coast, BEST Energies Australia, a company researching clean energy technology, has built a demonstration pyrolysis plant with the capacity to process 300 kilograms of dry green waste, wood waste, rice hulls, cow and poultry manure or paper mill waste every hour.
