Cut your grass and eat it too– Is aviation biofuel production and grazing in the Australian tropics possible?

The aviation industry is vulnerable to fuel price rises and carbon emission penalties. The use of bio-jet fuel will reduce emissions. However, there is only limited capacity for aviation fuel production in Australia. In a developing bio-jet fuel industry, it is not known whether there is sufficient biomass available at a reasonable price to support an industry. The literature identifies grasses as having good potential as a cost effective feedstock based on high productivity in tropical and subtropical cattle grazing areas, where there is limited competition with high value crops. Here we present an approach for assessing the biomass potential of grazing lands and apply it to a case study region in Australia. Biomass modelling showed grass biomass production in excess of grazing needs in favourable years of 1Mt within an area of 2500km2. This exceeds the demand of medium to large scale biofuel production facilities. The location of high production areas is variable over years but there are several consistent ‘hotspots’ of biomass production. However, in low rainfall years there is insufficient biomass produced to supply a bioenergy facility. The seasonal rainfall pattern in the area also requires storage of material for several months as harvesting in the wet season is undesirable. Cost for production of baled grass biomass (not including nutrient replacement and profits) to farm gate ranges from AU$50–$110/t. The opportunity cost for diverting grass from beef production to biomass for bioenergy is around AU$50/t. However, grass production for bioenergy would provide enterprise diversification options and environmental management benefits through reducing grazing impacts during the wet season in favour of dry season biomass harvest. The work highlights a potential for co-existence between biomass harvested for bioenergy and grazing systems, but more detailed research is required on environmental impacts and socio-economic considerations before considering implementation.

[1]  R. Furbank,et al.  C4 plants as biofuel feedstocks: optimising biomass production and feedstock quality from a lignocellulosic perspective. , 2011, Journal of integrative plant biology.

[2]  T. Richard.  Challenges in Scaling Up Biofuels Infrastructure , 2010, Science.

[3]  Alexander Herr,et al.  The economics of producing sustainable aviation fuel: a regional case study in Queensland, Australia , 2015 .

[4]  Damien R. Farine,et al.  Watching grass grow in Australia: is there sufficient production potential for a biofuel industry? , 2012 .

[5]  S. Roxburgh,et al.  A critical overview of model estimates of net primary productivity for the Australian continent. , 2004, Functional plant biology : FPB.

[6]  D. Post,et al.  Sustainable grazing for a Healthy Burdekin Catchment , 2003 .

[7]  C. Stokes,et al.  Natural Resource Management in the Burdekin Dry Tropics: Social and Economic Issues:. Report for the Burdekin Dry Tropics NRM Board , 2003 .

[8]  J. McIvor,et al.  The northern Australian beef industry, a snapshot. 3. Annual liveweight gains from pasture based systems , 2005 .

[9]  Alexander Herr,et al.  An assessment of biomass for bioelectricity and biofuel, and for greenhouse gas emission reduction in Australia , 2012 .

[10]  T. J. Danaher,et al.  A field method for statewide ground-truthing of a spatial pasture growth model , 2000 .

[11]  R. Cowley,et al.  Looking back in time: can safe pasture utilisation rates be determined using commercial paddock data in the Northern Territory? , 2011 .

[12]  L. Hunt.  Safe pasture utilisation rates as a grazing management tool in extensively grazed tropical savannas of northern Australia , 2008 .

[13]  M. Bhende,et al.  Impact of diversification on household income and risk: A whole-farm modelling approach , 1994 .

[14]  The northern Australian beef industry, a snapshot. 4. Condition and management of natural resources , 2005 .

[15]  Reinu E. Abraham,et al.  Biofuel production: Prospects, challenges and feedstock in Australia , 2012 .

[16]  D. M. Orr,et al.  Northern Australian savannas: management for pastoral production , 1990 .

[17]  J. Kirkpatrick,et al.  Frequent mowing is better than grazing for the conservation value of lowland tussock grasssland at Pontville, Tasmania , 2005 .

[18]  A. Herr,et al.  Understanding Adoption of On-farm Conservation Practices in the Burdekin Dry Tropics, Queensland , 2004 .

[19]  Alexander Herr,et al.  Second harvest–Is there sufficient stubble for biofuel production in Australia? , 2012 .

[20]  T. Brinsmead,et al.  Quantifying spatial dependencies, trade‐offs and uncertainty in bioenergy costs: an Australian case study (2) – National supply curves , 2015 .

[21]  J. McIvor,et al.  The northern Australian beef industry, a snapshot. 2. Breeding herd performance and management , 2005 .

[22]  A. Parker,et al.  Australia: Biomass energy holds big promise , 2012, Nature.

[23]  B. Bryan,et al.  Mitigating economic risk from climate variability in rain-fed agriculture through enterprise mix diversification , 2012 .

[24]  Alexander Herr,et al.  Bioenergy in Australia: An improved approach for estimating spatial availability of biomass resources in the agricultural production zones , 2011 .

[25]  Katalin Bódis,et al.  Optimal energy use of agricultural crop residues preserving soil organic carbon stocks in Europe , 2015 .

[26]  G. Bortolussi,et al.  The northern Australian beef industry, a snapshot. 1. Regional enterprise activity and structure , 2005 .

[27]  Characteristics of a bunch spear grass (Heteropogon contortus (L). BEAUV.) pasture grazed by cattle in subtropical Queensland. , 1955 .