A Spatial Modeling Framework to Evaluate Domestic Biofuel-Induced Potential Land Use Changes and Emissions

Abstract

We present a novel bottom-up approach to estimate biofuel-induced land-use change (LUC) and resulting CO2 emissions in the U.S. from 2010 to 2022, based on a consistent methodology across four essential components: land availability, land suitability, LUC decision-making, and induced CO2 emissions. Using high-resolution geospatial data and modeling, we construct probabilistic assessments of county-, state-, and national-level LUC and emissions for macroeconomic scenarios. We use the Cropland Data Layer and the Protected Areas Database to characterize availability of land for biofuel crop cultivation, and the CERES-Maize and BioCro biophysical crop growth models to estimate the suitability (yield potential) of available lands for biofuel crops. For LUC decision-making, we use a county-level stochastic partial-equilibrium modeling framework and consider five scenarios involving annual ethanol production scaling to 15, 22, and 29 BG, respectively, in 2022, with corn providing feedstock for the first 15 BG and the remainder coming from one of two dedicated energy crops. Finally, we derive high-resolution above-ground carbon factors from the National Biomass and Carbon Data set to estimate emissions from each LUC pathway. Based on these inputs, we obtain estimates for average total LUC emissions of 6.1, 2.2, 1.0, 2.2, and 2.4 gCO2e/MJ for Corn-15 Billion gallons (BG), Miscanthus × giganteus (MxG)-7 BG, Switchgrass (SG)-7 BG, MxG-14 BG, and SG-14 BG scenarios, respectively.

Recent grassland losses are concentrated around U.S. ethanol refineries

“…Comparatively limited attention to domestic ILUC effects has focused on the substitution of distillers' grains in confined animal feeding operations [40,41]. Interestingly, we observed approximately ten-times less forest conversion to cropland ( figure 5(b)) than projected by these models [40,41], but two-times more grassland conversion (tables S4, S5). In sum, our results suggest, at least anecdotally, that further attention should be given to potential ILUC associated with spatially diffuse adaptations to higher feed costs beyond the substitution of ethanol by-products.…”

“…International, indirect land use-change (ILUC) effects of U.S. ethanol production have been controversial and extensively studied [39]. Comparatively limited attention to domestic ILUC effects has focused on the substitution of distillers' grains in confined animal feeding operations [40,41]. Interestingly, we observed approximately ten-times less forest conversion to cropland ( figure 5(b)) than projected by these models [40,41], but two-times more grassland conversion (tables S4, S5).…”

Bioenergy crop productivity and potential climate change mitigation from marginal lands in the United States: An ecosystem modeling perspective

“…If we assume marginal land to be carbon neutral, the GHG emissions due to cropping of switchgrass and Miscanthus would result in a net carbon source in the marginal land. For switchgrass, especially when grown with high N input in the marginal land, the GHG intensity could exceed the earlier estimates for land use changes from cropland, grassland, and forest to cropping switchgrass (Dunn et al ., ; Elliott et al ., ) (Table ).…”

“…For example, many LCA studies (e.g. Dunn et al ., ; Elliott et al ., ) included GHG emissions induced by land use change (e.g. converting cropland, grassland, or forest to bioenergy crops), which could assess possible C pool changes during land conversion.…”

Evaluation of Microalgae Biofuel Production Potential and Cultivation Sites Using Geographic Information Systems: A Review

“…Lignocellulosic, non-food feedstocks, often referred to as second-generation bioenergy crops, are envisioned to meet the majority of the US biofuel targets in an environmentally sustainable way [1]. But land use change and associated emissions from planting non-food feedstocks raise concerns about environmental trade-offs of these crops [2]. Further, due to its low density and large area requirements, lignocellulosic biomass production requires development of highly efficient supply chain logistics and management systems [3].…”