Characterizing variability and reducing uncertainty in estimates of solar land use energy intensity

Estimates of the amount of land used for a defined amount of utility-scale electricity generation in the solar power industry, referred to here as solar land use energy intensity (LUEI), are important to decision makers for evaluating the environmental impact of energy technology choices. However, these estimates for solar LUEI are calculated using three difficult-to-compare metrics and vary by as much as 4 orders of magnitude (0.042–64m2/MWh) across the available literature. This study reduces, characterizes, and explicates the uncertainty in these values for photovoltaic (PV) and concentrated solar power (CSP) technologies through a harmonization process. In this harmonization process, a common metric is identified and data existing in other forms are converted to the metric, where possible; standard algorithms for calculating solar LUEI are developed; gaps and deficiencies in the literature calculations are identified and remedied; and differences among the resulting estimates are characterized and analyzed. The resulting range of harmonized solar LUEI estimates is reduced to 2 orders of magnitude [5–55 (m2y)/MWh]. Due to variables such as technology and location, there is a significant amount of irreducible variability in general solar LUEI estimates. However, this variability does not necessarily represent uncertainty, as most of it can be explained by choices in calculation input parameters. This study finds that key solar technology- and location-dependent parameters such as insolation, packing factor, system efficiency, and capacity factor all vary widely across studies, and thus all share in the overall variability of solar LUEI. Only land use at the site of solar electricity generation facilities is considered because lifecycle land use beyond the site (for manufacturing, disposal, etc.) is not widely accounted for in the existing literature. This study provides a basis for moving forward with standardized and comparable solar land use studies and for filling gaps in lifecycle solar LUEI.