Greenhouse gas emission balance of biofuel feedstock for potential carbon trading

Abstract

As global demand for energy increases, interest in developing renewable biofuels also increases, although the efficiency and viability of renewable energy production remain uncertain. Crop choice, agricultural management practices, and water usage are major factors in determining optimal management strategies for sustainable biofuel feedstock production. Although some conservation measures may decrease yields, improvements in water use efficiency, soil carbon storage and reductions in greenhouse gas (GHG) flux may counteract the decrease in biomass within an environmental sustainability framework. Here, two biofuel feedstock crops, sugarcane (Saccharum officinarum) and Napier grass (Pennisetum purpureum) were analyzed to compare the net benefits for four simulated outcomes with respect to irrigation level (100% and 50%) and agricultural practices (conventional and ratoon). The ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) crop simulation model, previously calibrated and validated for tropical grass production systems on Maui, was employed to estimate yields, total soil carbon and nitrous oxide, which were coupled with cost of production data obtained from Hawaiian Commercial and Sugar Company and integrated into a benefit-cost analysis framework. The results indicate that the sustainability and economic feasibility of biofuel feedstock production depend upon a change in current management practices.