Australia Draws Energy, Carbon and Oil from Eucalypt Trees

PERTH, Australia, December 15, 2000 (ENS) - A unique process of biomass energy production will be used in a demonstration plant planned for Western Australia.

The facility will turn a variety of eucalyptus trees known as mallee trees into energy, high value activated carbon and eucalyptus oil. As they grow, the trees will alleviate water and salinity management problems and absorb the greenhouse gas carbon dioxide.

The Integrated Wood Processor will be built by Western Power, the largest electric utility in Western Australia, at a site in Narrogin, south of Perth.

The plant will generate electricity and produce activated carbon using a process developed by the Commonwealth Scientific & Industrial Research Organisation (CSIRO), the Australian government's research branch.

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Western Australia's Energy Minister Colin Barnett (Photo courtesy government of Western Australia)

The full scale demonstration plant, equipped to handle 20,000 tons a year of whole mallee trees, will be built next year. It will produce 700 tons of activated carbon and 200 tons of eucalyptus oil annually, and have an electrical generation capacity of about one megawatt, said Western Australia's Energy Minister Colin Barnett.

"The CSIRO technology uses special fluidised bed burners which partially burn wood producing charcoal,” explains CSIRO’s Paul Fung. “This releases more than half the energy originally in the wood and provides steam that will power electricity generation. Steam activation technology then converts the charcoal to activated carbon."

The project involves mass planting of mallee eucalypt trees to help solve the wheatbelt's large and rapidly growing salinity problem by lowering the water table.

Extensive work has already been done by the Department of Conservation & Land Management and the Oil Mallee Company of Australia to develop mallee tree planting and harvesting to meet requirements of the IWP plant.

"We are pleased that this technology is to be used in this important renewable energy project,” explains Colin Stucley of Enecon, the company licensed to develop applications for the technology. “This new IWP industry has great potential to contribute simultaneously to the solution of several major environmental and greenhouse issues while creating a valuable new industry and employment in rural Western Australia."

Mallee planting can be used to manage water and salinity, but large scale planting needs commercial outlets for the wood and leaves to be economically viable. Officials say the IWP plants employing the CSIRO/Enecon process will provide this control.

Larger plants will have annual output of 3,500 tons of activated carbon products from 100,000 tons of whole mallee trees, and will supply five megawatts of electricity to the power grid.

The original project will produce eucalyptus oil that will be distilled from the mallee leaves using steam produced during wood processing. A continuous distillation process has been developed by researchers at Curtin University.

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Rows of oil mallee trees grown with crops planted between the rows. (Photo courtesy CSIRO)
"Tests have shown these carbons are very effective in the removal of colour, taste, odour and other contaminants from Australian drinking water supplies,” adds Fung, who says that work on mallee based activated carbon shows considerable potential. “Application in water treatment both in Australia and in the large overseas markets is envisaged.”

Last year, the IWP process received an award from the international journal "Chemical Engineer," which described the process as an elegant chemical engineering solution to a number of environmental problems in Australia and elsewhere. IWP received another energy and environment award in the 2000 Rabobank Agribusiness awards in Melbourne, Australia.

The project has support from hundreds of wheatbelt farmers and the Western Australia Department of Conservation & Land Management, which is developing special equipment to allow a harvest of the fast resprouting trees every few years once hedgerows are established. The Western Power utility is the major financial supporter of the project, assisted by the Australian Greenhouse Office and AusIndustry.

While the above ground portion of the tree is harvested, the large root systems below ground continue to grow, store carbon and contribute to the long term survival of the trees. In addition to their water management and commercial uses, these sustainably managed mallee hedgerows will act as sinks for the greenhouse gas carbon dioxide.