Aggressive renewable energy policies have helped the biofuels industry grow at a rate few could have predicted. However, while discourse on the energy balance and environmental impacts of agricultural biofuel feedstocks are common, the potential they hold for additional production has received considerably less attention. Here we present a new biofuel yield analysis based on the best available global agricultural census data. These new data give us the first opportunity to consider geographically-specific patterns of biofuel feedstock production in different regions, across global, continental, national and sub-national scales. Compared to earlier biofuel yield tables, our global results show overestimates of biofuel yields by ~100% or more for many crops. To encourage the use of regionally-specific data for future biofuel studies, we calculated complete results for 20 feedstock crops for 238 countries, states, territories and protectorates.

http://iopscience.iop.org/article/10.1088/1748-9326/4/1/014004/pdf

Resetting global expectations from agricultural biofuels

Proportion of above-ground biomass in commercial logs and residues following the harvest of five commercial forest species in Australia

Autohydrolysis explosion pretreatment of hardwood (Eucalyptus regnans) sawdust at 200°C and 6.9 MPa gas pressure (steam + nitrogen) for 5 min solubilized 85% of the total hemicellulose components and produced a pulp that was highly accessible to attack by cellulases from Trichoderma reesei C-30 and by a commercial preparation, Meicelase. The autohydrolysis liquor, representing 15% of the original weight of the sawdust on a solids basis, consisted mainly of xylose, xylose oligomers and minor amounts of galactose, mannose, arabinose, glucose and uronic acids. Enzymic hydrolysis of pretreated E. regnans pulps using Trichodermal cellulases resulted in saccharification yields of <50% within 24 h from 10% (w/v) substrate slurries and 20 cellulase (FPU) units per g of pretreated pulp. The cellulose-to-glucose conversions were lower and this was attributable to the production of a compound(s) during enzymic hydrolysis that was inhibitory to the β-glucosidase component, but not the cellulases, in the Trichodermal ...

Pretreatment of hardwood (eucalyptus regnans) sawdust by autohydrolysis explosion and its saccharification by trichodermal cellulases

Information on Australian biomass resources including bagasse, black liquor from paper pulp production, wood waste and forestry residues, energy crops, crop wastes, food and agricultural wet waste, and municipal solid wastes is provided in the review. The characteristics of the Australian biomass are typical of those of other countries, i.e. high moisture and volatile matter, low heating value and density, and low sulfur and nitrogen content, but high Ca and Mg for woody biomass. The characteristics influence biomass utilization. Biomass is used extensively at present within Australia, primarily for domestic heating, as bagasse in the sugar industry, and for electricity generation. Biomass usage for electricity generation is increasing and is expected to reach 5.2 Mt/year by 2019-20. Exports, as wood chips, are approximately 10 Mt/year in 2000-01. Forestry residues have been estimated to be 23 Mt/year. Current technologies that utilize biomass in Australia include those for electricity and heat by direct combustion, cofiring with coal and fluidized bed combustion), for biogas generation (from landfills, and aerobic digestion, and as bio-liquids. Related to bio-liquid fuels, ethanol production from molasses and wheat is being progressed. The resultant ethanol is used as a petrol extender, and a bio-diesel process is under development.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_01_1_093_115_Mohthtaderi_SW_Australian_Biomass_Resources_Utilization/125

An overview of the australian biomass resources and utilization technologies

A linear programming analysis of liquid-fuel production and use options for Australia

This report is a preliminary assessment of the potential for production of liquid fuels for transport from agricultural and forestry resources in Australia in the next 20 to 40 years, using existing or near- term technologies. These resources include both residues from existing production and crops grown especially as fuel crops on lands that are not used for crops at present. If properly managed they would be renewable fuel resources that could supply liquid fuels indefinitely. The liquid fuels considered are ethanol and methanol. The estimated total net liquid fuel from the sources considered is approximately 420 pj, which is more than half of the 1977-78 use of liquid fuel in transport in Australia of about 700 pj. Thus these sources could make a significant contribution to our liquid fuel needs. The main potential contribution would be from a virtual doubling of the cereal grain and the sugarcane industries. Pure alcohol fuels at the conversion plant using present commercial technology could cost more than three times the 1975-76 price of equivalent motor spirit ex refinery. Adding taxes, distribution costs, and retail costs, their estimated retail cost would be more than twice the retail price of motor spirit. The estimated cost of production of methanol from coal is much lower than the cost of alcohol fuels from biomass. There are no economic reasons for turning to the renewable resource- based alcohol fuels at present. (TRRL)

W. H. M. Rawlins

Papers

The Potential for liquid fuels from agriculture and forestry in Australia