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We provide a quantitative assessment of the prospects for current and future biomass feedstocks for bioenergy in Australia, and associated estimates of the greenhouse gas (GHG) mitigation resulting from their use for production of biofuels or bioelectricity. National statistics were used to estimate current annual production from agricultural and forest production systems. Crop residues were estimated from grain production and harvest index. Wood production statistics and spatial modelling of forest growth were used to estimate quantities of pulpwood, in-forest residues, and wood processing residues. Possible new production systems for oil from algae and the oilseed tree Pongamia pinnata, and of lignocellulosic biomass production from short-rotation coppiced eucalypt crops were also examined. The following constraints were applied to biomass production and use: avoiding clearing of native vegetation; minimizing impacts on domestic food security; retaining a portion of agricultural and forest residues to protect soil; and minimizing the impact on local processing industries by diverting only the export fraction of grains or pulpwood to bioenergy. We estimated that it would be physically possible to produce 9.6 GL yr À1 of first generation ethanol from current production systems, replacing 6.5 GL yr À1 of gasoline or 34% of current gasoline usage. Current production systems for waste oil, tallow and canola seed could produce 0.9 GL yr À1 of biodiesel, or 4% of current diesel usage. Cellulosic biomass from current agricultural and forestry production systems (including biomass from hardwood plantations maturing by 2030) could produce 9.5 GL yr , or ca. 15% of current electricity production. New production systems using algae and P. pinnata could produce ca. 3.96 and 0.9 GL biodiesel yr À1 , respectively. In combination, they could replace 4.2 GL yr À1 of fossil diesel, or 23% of current usage. Short-rotation coppiced eucalypt crops could provide 4.3 GL yr À1 of ethanol (2.9 GL yr À1 replacement, or 15% of current gasoline use) or 20.2 TWh yr À1 of electricity (9% of current generation). In total, first and second generation fuels from current and new production systems could mitigate 26 Mt CO 2 -e, which is 38% of road transport emissions and 5% of the national emissions. Second generation fuels from current and new production systems could mitigate 13 Mt CO 2 -e, which is 19% of road transport emissions and 2.4% of the national emissions lignocellulose from current and new production systems could mitigate 48 Mt CO 2 -e, which is 28% of electricity emissions and 9% of the national emissions. There are challenging sustainability issues to consider in the production of large amounts of feedstock for bioenergy in Australia. Bioenergy production can have either positive or negative impacts. Although only the export fraction of grains and sugar was used to estimate first generation biofuels so that domestic food security was not affected, it would have an impact on food supply elsewhere. Environmental impacts o...

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