Integrated Wood Processing (IWP)

The Oil Mallee Company and CALM recognised in the early 90's that it was going to be difficult to ensure the profitability of oil mallees if eucalyptus oil was the only source of revenue. Consequently over several years, various other products derived from oil mallees were assessed. This led to the concept of integrated production and use of oil mallee products.

The Oil Mallee Company, Western Power Corporation, Enecon and CALM have recently been investigating an IWP system where oil, charcoal, activated carbon, and electricity are all produced in a combined process.

Preliminary work has demonstrated that this system can produce all products at viable prices and give growers a return competitive with their other crop options. Western Power has just finished securing the last of the $5 million needed to build a demonstration plant in Narrogin.

The Integrated Wood Processing plant (IWP) will produce electricity, charcoal, activated carbon, and eucalyptus oil, from mallee feedstock grown on farms in the Wheatbelt of Western Australia. All four products can be produced economically by sharing the infrastructure and maximising use of the feedstock. The activated carbon technology is Australian, developed by the CSIRO.

Fully commercial plants are expected to produce the following annually, from 100,000 tonne of mallee feedstock material supplied by some 10 million mallees:

• 5 MW of electricity

• 1000 tonne eucalyptus oil, and

• 3500 tonne of activated carbon

Once at the plant, the harvested mallee biomass (woodchip size material) will be separated into leaf and wood components.

The leaf component will be fed into a still, to extract the eucalyptus oil via steam extraction. The steam strips oil from the leaves and is condensed to produce a distillate from which the oil readily separates. Traditionally in the past, this has been done in batches, using simple, small stills out in the bush. This method is energy intensive though, and thus inefficient and expensive.

The OMC has developed a way in which steam distillation can be reduced in cost by being conducted in a continuous flow process and on a large scale using modern technologies. With steam being available at the IWP plant as a by-product of other processing activities (i.e. the activating of charcoal to make activated carbon), further gains in efficiency are possible.

The wood fraction of the mallee biomass is fed into a different part of the plant, a fluidised bed carboniser, which is CSIRO technology licensed to Enecon. The Fluidised Bed Carboniser (FBC) system allows controlled combustion of the mallee wood into charcoal which creates steam for the turbo-generator. The charcoal will then be activated by steam to produce water gas and activated carbon. The water gas will be used to generate more steam. Steam will also be used in the distillation of oil from the mallee leaves (continuous distillation). Overall emissions are very low.

All spent leaf and wood residues are then dewatered and used as a fuel for steam generation. The steam is then fed into a steam turbine to produce renewable energy.

The pilot plant will initially produce 1 MW of 'green' electricity, and when fully scaled up to a commercial size plant, will produce 5 MW a year.

Read more on the Narrogin Bioenergy Plant Demonstration of integrated Wood Processing.

Click on the pic to see the flow diagram on producing 'green electricity'

Operation of a plant like this offers significant employment opportunities for rural communities. The plant will operate 24 hours per day and a fully commercial plant is likely to create employment for up to 20-30 people. Additional jobs will come from the planting, harvesting and transport of trees.

Western Power has identified up to 10 potential sites around the state, for future IWP plants to be built. Basically, wherever there are substantial plantings, and access to the Transmission System on to the grid, there is an opportunity to build an IWP plant.

Check LATEST NEWS page for regular updates on the progress of the IWP pilot plant being built in Narrogin!