Speaking at the Bioenergy and Biofuels in WA conference on Friday, Curtin University’s Dr Hongwei Wu said the oil mallee tree “blitzed” the competitors during an energy ratio test of biofuel production.
The mallee tree can provide 3159 litres of ethanol per hectare, compared with corn at 3110 litres per hectare, Wu said.
Mustard seed produced 606 litres of biodiesel per hectare, with canola at 438 litres.
Mallee can produce 41.7 times more energy than is used in its cultivation, providing a substantially higher return on energy investment than corn, canola and mustard, which have energy ratios ranging between 5.6 and 10.
“Based on this analysis, the mallee-to-ethanol scenario looks like being the most promising out of all the crops,” Wu said.
He said another advantage of the mallee-ethanol model is the adoption of an “alley farming” concept, in which trees only cover 10% of the total farming land, leaving most of the land available for other crops.
In comparison, productivity from the other crops required 100% ground coverage.
Researchers from Monash University in Melbourne are already investigating how to convert the mallee tree into biodiesel.
Project leader Dr Damon Honnery said mallee wood could be super-heated to produce a vapour that could then be condensed into liquid to run diesel engines.
Honnery said the oil was not yet suitable for car engines as the filtering systems were too fine, and it had only been used in a test engine, but he believed appropriate refining process could be developed within the next 10 years.
Planting these trees could also help Australia's soil salinity problem as their complex root system reduced water table problems, according to Honnery.
"The fuel is almost greenhouse neutral, so we get three benefits – we can help solve salinity, we can help to solve and reduce greenhouse gas emissions from transport, and we get to produce a fuel as well," he said.