The Fuel Cycles of Electricity Generation: A Comparison of Land Use
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The Fuel Cycles of Electricity Generation: A Comparison of Land Use Hyung Chul Kim1, and Vasilis Fthenakis1,2 1 PV Environmental Research Cener, Brookhaven National Laboratory, Upton, NY, 11973 2 Center for Life Cycle Analysis, Columbia University, New York, NY, 10027 ABSTRACT We investigate the area of land used and/or transformed during conventional (i.e., coal, natural gas and nuclear), and renewable fuel cycles (i.e., photovoltaics, wind, biomass, and geothermal). Both direct and indirect land use/transformation are examined in a life cycle framework. For average US insolation, the photovoltaic fuel cycle disturbs the least amount of land per GWh among renewable options, requiring less area than the coal fuel cycle. Renewable technologies could harvest infinite amount of energy per unit area and eliminates the need for restoring disturbed mine lands. Further investigations would be necessary for secondary and accidental land disturbance by conventional fuel cycles through transport of effluents and emissions to adjacent land. INTRODUCTION Renewable energy sources such as photovoltaics (PV) and biomass are often criticized as requiring a large amount of land compared to other energy options [1, 2]. However, life-cycle based land assessments present a different picture; conventional fossil fuel cycles require large amounts of land when we accounting the land for fuel extraction [3, 4]. In this article we review the life cycle land use for conventional fuel cycles (i.e. coal, nuclear, and natural gas), and renewable fuel cycles, (i.e. PV, wind, geothermal and biomass). Land use metrics are parsed into land transformation (unit: m2) and land occupation (unit: m2 x year). The former, which is employed in this study, indicates the area of land altered from a reference state while the latter indicates the land area and the duration of occupation. Direct land usage was compiled from US Department of Energy (DOE) reports while indirect land usage was compiled from the life cycle assessments and energy data. Land use impacts across electricity generation options were compared. COAL For the coal fuel cycle, the direct land transformation is primarily related to the coal extraction, electricity generation, and waste disposal stages while the indirect land use refers to the upstream land use associated with energy and materials inputs during the fuel cycle. The sources of direct land transformation data include Ecoinvent, a commercial database, an LCA literature and DOE reports [3-7]. The land transformation factors in the Ecoinvent database were used for estimating the indirect land usages. Land use statistics during coal mining vary with factors including heating value, seam thickness, and mining methods. Surface mining in the Western US tends to disturb less area (per unit coal mined) than in other areas due to the thick seams, 2-9 m. Central states where seam thickness is only 0.5-0.7 m, transform the largest area for the same amount of coal mined (Figure 1). On the other hand, underground mining transforms
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