National Geo-Database for Biofuel Simulations and Regional Analysis
The goal of this project undertaken by GLBRC (Great Lakes Bioenergy Research Center) Area 4 (Sustainability) modelers is to develop a national capability to model feedstock supply, ethanol production, and biogeochemical impacts of cellulosic biofuels. The results of this project contribute to sustainability goals of the GLBRC; i.e. to contribute to developing a sustainable bioenergy economy: one that is profitable to farmers and refiners, acceptable to society, and environmentally sound. A sustainable bioenergy economy will also contribute, in a fundamental way, to meeting national objectives on energy security and climate mitigation. The specific objectives of this study are to: (1) develop a spatially explicit national geodatabase for conducting biofuel simulation studies; (2) model biomass productivity and associated environmental impacts of annual cellulosic feedstocks; (3) simulate production of perennial biomass feedstocks grown on marginal lands; and (4) locate possible sites for the establishment of cellulosic ethanol biorefineries. To address the first objective, we developed SENGBEM (Spatially Explicit National Geodatabase for Biofuel and Environmental Modeling), a 60-m resolution geodatabase of the conterminous USA containing data on: (1) climate, (2) soils, (3) topography, (4) hydrography, (5) land cover/ land use (LCLU), and (6) ancillary data (e.g., road networks, federal and state lands, national and state parks, etc.). A unique feature of SENGBEM is its 2008-2010 crop rotation data, a crucially important component for simulating productivity and biogeochemical cycles as well as land-use changes associated with biofuel cropping. We used the EPIC (Environmental Policy Integrated Climate) model to simulate biomass productivity and environmental impacts of annual and perennial cellulosic feedstocks across much of the USA on both croplands and marginal lands. We used data from LTER and eddy-covariance experiments within the study region to test the performance of EPIC and, when necessary, improve its parameterization. We investigated three scenarios. In the first, we simulated a historical (current) baseline scenario composed mainly of corn-, soybean-, and wheat-based rotations as grown existing croplands east of the Rocky Mountains in 30 states. In the second scenario, we simulated a modified baseline in which we harvested corn and wheat residues to supply feedstocks to potential cellulosic ethanol biorefineries distributed within the study area. In the third scenario, we simulated the productivity of perennial cropping systems such as switchgrass or perennial mixtures grown on either marginal or Conservation Reserve Program (CRP) lands. In all cases we evaluated the environmental impacts (e.g., soil carbon changes, soil erosion, nitrate leaching, etc.) associated with the practices. In summary, we have reported on the development of a spatially explicit national geodatabase to conduct biofuel simulation studies and provided initial simulation results on the potential of annual and perennial cropping systems to serve as feedstocks for the production of cellulosic ethanol. To accomplish this, we have employed sophisticated spatial analysis methods in combination with the process-based biogeochemical model EPIC. This work provided the opportunity to test the hypothesis that marginal lands can serve as sources of cellulosic feedstocks and thus contribute to avoid potential conflicts between bioenergy and food production systems. This work, we believe, opens the door for further analysis on the characteristics of cellulosic feedstocks as major contributors to the development of a sustainable bioenergy economy.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1046329
- Report Number(s):
- PNNL-21284; BM0102030; TRN: US201215%%438
- Country of Publication:
- United States
- Language:
- English
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