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Biosystems Engineering has designed and built the Bionic Beaver, a short rotation woody crop harvester in collaboration with the Future Farm Industries Cooperative Research Centre and the WA Department of Environment and Conservation.

The Bionic Beaver is a world-first in engineering and innovation.

The machine is an efficient upright biomass harvester that can cut and chip woody biomass in one continuous operation, analogous to how farmers harvest forage crops.

A history of the Bionic Beaver

The original prototype of the Bionic Beaver was developed in Western Australia between the mid 1990s and early 2000s by Western Australian engineer Harley Pederick and Department of Conservation and Land Management researcher Rick Giles. This harvester was developed to harvest mallees, which are a group of many species of eucalyptus trees adapted to regenerate from an underground lignotuber.

At that time in Europe, sugar cane harvesters were being modified to harvest willow. This inspired a group of WA mallee growers to purchase a second-hand sugar cane harvester, but this did not work well with mallee, so the development of a new type of machine was required. Harley Pederick joined the team and his work was fundamental in identifying and testing the components that make the Bionic Beaver design of today. 

In conjunction with Harley, research by the then Western Australian Department of Conservation and Land Management (now the Department of Environment and Conservation), supported by independent systems analysis, concluded that a one-pass harvester process which converts the structurally complex mallee trees into a bulk chipped commodity had the greatest potential to reduce the per-tonne cost for the woody biomass supply chain for small trees. 

The study also showed that due to the diverse nature of the mallees, a successful short rotation woody crop harvester would have to be applicable to a wide range of small tree shapes and sizes, and this in turn would open the opportunity to develop other native Australian species as woody crop plants. 

Realising the potential of the Western Australian mallee industry, energy company Verve Energy set up a pilot-scale Integrated Wood Processing (IWP) plant near Narrogin in 2005.

Trial runs at the pilot IWP plant showed mallee biomass can generate commercial quantities of electricity while producing activated carbon and eucalyptus oil within an integrated plant. Using information collected from the pilot-scale plant trial, Verve Energy then conducted a Front End Engineering Design (FEED) process for a commercial scale IWP plant during 2008-09. 

In April 2009, Verve Energy stated it could be some time before a commercial mallee processing plant is established in Western Australia due to the economic climate.

The promise revealed by the pilot IWP highlighted the need to rejuvenate harvester development and indeed to consider all the components in the farm to factory supply chain. 

The Future Farm Industries Co-operative Research Centre (FFICRC) took up the challenge of continuing the development of short rotation woody crop harvester in 2007 with the WA Department of Environment and Conservation in WA, the Oil Mallee Company and Verve Energy remaining partners in the project.

In June 2008, the Western Australian government announced it would provide $1.5 million to the FFICRC from its Low Emission Energy Development (LEED) fund to develop a prototype commercial short rotation woody crop harvester.  

The funding was conditional on FFICRC attracting additional private sector funding.  Biosystems Engineering was appointed by FFICRC in March 2009 as a partner to conduct the project’s applied Research and Development (R&D) component including the design and manufacture of a prototype short rotation woody crop harvester. 

The prototype harvester’s unique attribute is that it grabs and chips the trees vertically, leveraging gravity to make the process energy-efficient. The concept was dreamed up by Harley Pederick and FFICRC researcher Rick Giles and made real by Biosystems Engineering.

The prototype harvester began its first round of testing in April 2010 and subsequent testing was carried out in late 2010.

According to Biosystems Engineering’s Richard Sulman, conventional harvesting, bunching and chipping costs a minimum of $45 a tonne for small trees like mallee, whereas the prototype harvester, once fully developed, is expected to cost less than $25/t. Operating costs are comparable to modified forage harvesters, but the prototype can process trees with a larger range of stem diameters (70mm to 200mm).

The harvester works by driving continuously into short rotation woody crops and cutting them 100 millimetres from the ground before conveying them back to a pair of feed rollers and a chipper. After passing through the chipper, the harvester ejects wood chips and other biomass (at 230 kilometres an hour) via a chute into a truck or bin. The one-pass system improves operational efficiency by minimising handling.

A 100mm harvest height on mallee is followed by regeneration (coppicing), allowing them to regrow in time for the next harvest three to six years later. The interval between harvests depends upon annual rainfall.

Regular harvesting is expected to reduce the impact on nearby cereal crops and keep the woody crops to a height of about four to six metres, although the current prototype is designed to handle 8m trees with 150mm stems. Mr Sulman says the harvester can be scaled to suit 3m to 20m high trees with large end diameters up to 200mm.

The harvester processes a single tree every 2.5 seconds. During its first outing at Condobolin, NSW, Mr Sulman says the machine exceeded a performance indicator of 20 green tonnes an hour and recorded a capacity of up to 35t/h. He expects the prototype to achieve 40 to 50t/h with further development.

Since the machine’s first outing, there have been substantial modifications to the prototype and further trials to test the optimum way of delivering the trees to the chipper.

Also under development is an efficient on-farm transport system. This, combined with a modified harvester design, is expected to produce an efficient production rate of more than 50 green tonnes per hour. The optimum rate will be determined after further systems analysis and extensive field validation is completed in NSW, Victoria and WA later this year, in collaboration with CSIRO, Australia’s national science agency.