Can biomass satisfy our thirst for liquid fuels? An Australian Perspective

摘要

The consumption of petroleum-derived liquid fuels has risen to the equivalent of 6.5 litres per person per day in Australia according the Australian Institute of Petroleum. As oil recovery worldwide is likely to become more difficult and more expensive sometime in the future, alternative sources are being evaluated. Conversion of biomass into liquid hydrocarbons is one route being proposed to meet the prospective demand. This paper examines the extent of arable land in Australia and the types of biomass being considered for the purpose. Cane, switchgrass (or miscanthus) and species of Mallee are identified as suitable candidates, with Mallee offering the best solution in a dry continent. Gasification to syngas followed by condensation in a Fischer-Tropsch process uses the whole plant and can produce about 240 litres of hydrocarbons per tonne of dry biomass. This figure could be increased by using an external heat source for the gasifier. Taking this yield figure gives a total demand of 220 Mt of biomass per annum, which would entail plantations of Mallee covering over 500,000 km2. The conclusion is that for Australia, the total replacement of liquids by biomass processing is an unrealistic expectation.