Researchers at the NSW Department of Primary Industries’ Wollongbar Agricultural Institute are reducing the cost of making biofuels from crop residues – aiming eventually to have up to 20 per cent of the petrol used in NSW replaced with this renewable fuel source, Minister for Primary Industries Ian Macdonald said.
“DPI scientists are at the forefront of developing second-generation biofuels from low-cost, non-food materials or ‘waste’ materials such as crop stubble or forestry thinnings,” Mr Macdonald said.
“Rather than using grain or any other food source to make biofuels, they are breaking down lignocellulose – an abundant structural plant material like crop stubble or urban green waste – to make ethanol fuel.
“It is a fantastic initiative to find an alternative renewable fuel source from a waste product with real long-term benefits for NSW.”
Mr Macdonald said the research team at Wollongbar Agricultural Institute was currently investigating the fuel-making potential of wheat straw, sugarcane bagasse, sorghum stubble and a number of waste residues from Australian natives such as plantation eucalypt and oil mallee.
“Each of these crop residues has issues about how easily it can be gathered and harvested and how easily it can be made into ethanol,” he said.
“The aim is to reduce the costs of the process by as much as half to make it a genuinely viable source of fuel to replace around one-fifth of non-renewable fossil fuel use.”
NSW DPI scientist Dr Tony Vancov said producing ethanol from lignocellulose involved four to five operations, depending on the raw material feedstock.
“The first and most expensive step involves turning the raw material into a uniform feed stream and pre-treating it,” he said.
“At the moment our researchers are concentrating on pre-treatment platforms using heat and chemicals.
“We are changing the physical structure of the woody feedstock material by soaking it in a dilute acid or alkaline solution, then cooking it at different temperatures before using enzymes to break down the pulp to sugars and residual lignin.
“The sugar solution is subsequently fermented by yeast or bacteria, and the resulting ethanol stream is concentrated.
“Leftover lignin can also be used for electricity generation or bio products including biochar, which has soil carbon sequestration and agronomic benefits.”