Site Variation in Life Cycle Energy and Carbon Footprints of Mallee Biomass Production in Western Australia

Abstract

This study reports the site variations in life cycle energy and carbon footprints of mallee biomass from nine sites in Western Australia based on the latest field data and additional fertilizer application to compensate for nutrients exported from the sites. Across the sites, the energy and carbon footprints of mallee biomass range from 299 to 451 MJ/dry tonne and from -2.0 to 31.5 kg of CO2 equivalent (CO2-e)/dry tonne, equivalent to 5.8–8.7% of energy and -0.3–5.5% of carbon embedded in the biomass product at farm gate, respectively. Compensating for nutrient export clearly increases biomass energy and carbon footprints because of the increased fertilizer applications. Overall, the results show that mallee biomass production is close to being renewable and carbon-neutral. Selecting sites with a low initial soil carbon and achieving a high biomass yield can increase the soil carbon during biomass production, greatly reducing the carbon footprint of the produced biomass.