Human settlements

Renewable energy

Biomass 06: Bioenergy - Integrated mallee processing

Renewable Energy Commercialisation in Australia, Australian Greenhouse Office, 2003
NOTE: The status of these projects will have changed since the time of publication, and project contacts may also have changed.

Western Power's Integrated Wood Processing demonstration plant will process mallee trees to produce renewable electricity, activated carbon and eucalyptus oil.

Western Australia's wheatbelt town of Narrogin is home to an innovative project, the Integrated Wood Processing (IWP) demonstration plant that addresses global warming and farmland salinity, two of Australia's most pressing environmental concerns. Western Power is building the plant with the assistance of a $1 million grant under the Renewable Energy Commercialisation Program.

Using locally planted mallee trees, the IWP plant will generate enough renewable electricity for 1000 homes, as well as activated carbon and eucalyptus oil. Yielding three products at the one plant will ensure commercially competitive operation.

The electricity produced will displace fossil-fuelled generation and is carbon dioxide neutral. Because trees are planted specifically for the project, carbon dioxide is first fixed from the atmosphere as carbon, before being later released in the generation of electricity as carbon dioxide again. The carbon dioxide is essentially borrowed, not generated. Much of the fixed carbon stays with the activated carbon. In addition, there is a carbon store created when the land use is first changed from monoculture to agroforestry, and a continuing store in the roots, which continue to grow indefinitely.

The project needs local farmers to plant two million mallee trees. Mallees had been the bane of farmers since colonisation because of their stubborn habit of resprouting after attempted removal. Mallees store food and energy in their underground lignotuber, the wellknown mallee root, which allows them to regrow when the aboveground branches are removed, a natural adaptation to frequent fires.

This resprouting ability will be exploited to harvest branches every second year indefinitely without any replanting. This is known as 'coppicing'. Meanwhile, the deep mallee roots soak up the ground water to keep the salt at bay. Mallees are now the farmers' ally in combating salinity that threatens 30 per cent of the wheatbelt in Western Australia.

The IWP plant uses modern fluidised bed technology developed by CSIRO to convert the wood into charcoal and then to 'activate' the charcoal to convert it to activated carbon. Activated carbon is used in air and liquid purification. Oil will be distilled from the leaves, and the spent leaves will be gasified to produce fuel for the boiler. Initially the oil will be used in the pharmaceutical market, currently dominated by imports. It will also be pioneered as a safe, environmentally friendly industrial solvent. Heat from both processes will be used to generate electricity.

Enecon Pty Ltd, which holds the rights to commercialise the CSIRO technology, will be working with Western Power on the design, construction and operation of the plant. The Oil Mallee Company of Australia Pty Ltd will supply mallee biomass and new eucalyptus oil distillation technology.

TECHNICAL DETAILS

Biomass feed 20,000 tonnes/annum
Output
Electricity 7.5GWh/annum
Activated carbon 690 tonnes/annum
Eucalyptus oil 210 tonnes/annum
Plant design
Generation plant 1MW steam turbine
Carbonising plant Fluidised bed
Distillation plant Steam distillation
Spent leaf combustor Thermal gasification
Greenhouse gas abatement
Renewable energy generation 7,300 tonnes/annum
Rootmass fixation 4,300 tonnes/annum
Standing biomass fixation 54,000 tonnes

Full-scale, fully economic IWP plants will be five times the size of the demonstration plant, each requiring the planting of 20 million trees. There is potential for at least ten plants throughout the wheatbelt of Western Australia, with many more possible in other states and overseas.

For more information please contact

Adrian Chegwidden
Manager, Sustainable Energy Branch
Western Power Corporation
GPO Box L921
Perth WA 6842
Tel (08) 9326 4902
Fax (08) 9326 4600
Email adrian.chegwidden@wpcorp.com.au
Internet www.westernpower.com.au

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