Sunflower Cultivation on Coal Mine Refuse Piles in Appalachia for Diesel Biofuel Production from a Life-cycle Perspective

AbstractAs demand for alternatives to petroleum fuels increases to meet renewable fuel policy requirements (an attempt to address global climate change concerns) both agricultural production of biofuel feedstock and feedstock-to-fuel conversion pathways must be examined for both energy efficiency and sustainability. The overarching agricultural method evaluated in this research is that of cultivating low-input biofuel feedstock on marginal lands. With a growing body of literature on sunflower crops cultivated on marginal land, as well as previous work by these researchers, describing positive overall outcomes, this study extended the scope of that previous research conducted by this group, specifically, examining low-input sunflower feedstock production on abandoned mine lands in the Appalachia, and subsequent feedstock conversion to diesel fuel alternatives.The previous life cycle assessment (LCA) demonstrated that growing sunflower feedstock on a specific abandoned coal mine refuse pile in Appalachia for production of biodiesel would be environmentally sound and net-energy positive if conducted with low input agricultural practices, and if production continues five years after initial soil amelioration [1]. This LCA normalized the data and generalized the method in order to apply them to over 1000 coal mine refuse piles in three Appalachian states located through global information systems (GIS). Additionally, this study included two conversion pathways for diesel replacement biofuels, namely transesterification of sunflower oilseed for biodiesel production – included in the original LCA – and fast pyrolysis of sunflower silage for green diesel production – new to this study.The results of this study indicate when cultivating sunflower feedstock for biodiesel production on the average coal refuse pile in the Appalachian region produce approximately 11.6 barrels of biodiesel, plus 18.5 barrels of green diesel, with a similar environmental impact landscape to that of the specific site explored in the original LCA. Including the additional biofuel pathway of fast pyrolysis does alter the energy return outlook for the average Appalachian site, depending on the transportation distances and yields, the energy return varies greatly between sites, however overall environmental impacts only increase nominally. Site by site evaluation should be conducted before implementation to ensure the benefits outweigh negative impacts and a positive energy return is achieved.Because of the approximately 32 thousand barrels per year of renewable diesel biofuel which could be produced from 6642ha of coal refuse piles in only three states, it is highly recommended that the US Environmental Protection Agency (EPA) consider expanding the Renewable Fuel Standard (RFS) to include biofuel production on marginal land for Renewable Identification Number (RIN) assignment