Optimization based trade-off analysis of biodiesel crop production for managing a German agricultural catchment

Authors: LAUTENBACH, SVEN; VOLK, MARTIN - Helmholtz Centre; STRAUCH, MICHAEL - Dresden University; Whittaker, Gerald; SEPPELT, RALF - Martin Luther University

Submitted to: Environmental Modelling & Software
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2013
Publication Date: 8/31/2013
Citation: Lautenbach, S., Volk, M., Strauch, M., Whittaker, G.W., Seppelt, R. 2013. Optimization based trade-off analysis of biodiesel crop production for managing a German agricultural catchment. Environmental Modelling & Software. 48:98-112.

Interpretive Summary: In agricultural production, the existence of multiple trade-offs among several conflicting objectives, such as food production, water quantity, water quality, biodiversity and ecosystem services, is well known. However, quantification of the trade-offs among objectives in bioenergy crop production is problematic, and few results have been published. The trade-offs that have been quantified usually report a comparison of plausible scenarios, but do not consider whether the trade-offs are optimal or not. Unless optimal trade-offs are calculated, it is quite possible that the results from any given scenario could be achieved at lower cost with better environmental results, and the stakeholders have no way of knowing. In this study, we analyzed trade-offs among aspects of bioenergy crop production, food crop production, water quality and water quantity in the Parthe catchment in Central Germany. By calculating the Pareto optimal set, we are able to provide stakeholders with recommendations for the best way to achieve their personal preference, and to compare the optimal outcomes given different policy preferences. Analyzing bioenergy crop production based on rapeseed, we found that the same level of bioenergy crop production can be achieved at different costs with respect to the other objectives. Overall, we found a tendency to decreased low flow for solutions with higher yields of both rapeseed and food crops, while higher nitrate concentrations were related primarily to increasing yields of rapeseed.

Technical Abstract: In agricultural production, the existence of multiple trade-offs among several conflicting objectives, such as food production, water quantity, water quality, biodiversity and ecosystem services, is well known. However, quantification of the trade-offs among objectives in bioenergy crop production is problematic, and few results have been published. The trade-offs that have been quantified usually report a comparison of plausible scenarios, but do not consider whether the trade-offs are optimal or not. Unless optimal trade-offs are calculated, it is quite possible that the results from any given scenario could be achieved at lower cost with better environmental results, and the stakeholders have no way of knowing. Unless optimal trade-offs are calculated, it is quite possible that the results from any given scenario could be achieved at lower cost with better environmental results, and the stakeholders have no way of knowing. In this study, we analyzed trade-offs among aspects of bioenergy crop production, food crop production, water quality and water quantity in the Parthe catchment in Central Germany. The analysis was based on an integrated catchment model (SWAT) and a multi-objective genetic algorithm (NSGA II). The genetic algorithm was used to identify a representative sample of the Pareto optimal set of crop rotation schemes, where Pareto optimality describes solutions in which an objective cannot be improved without decreasing other objectives. This allowed us to quantify the trade-off among environmental effects in bioenergy crop production. We analyzed trade-offs among aspects of bioenergy crop production, food crop production, water quality and water quantity in the Parthe catchment in Central Germany. By calculating the Pareto optimal set, we are able to provide stakeholders with recommendations for the best way to achieve their personal preference, and to compare the optimal outcomes given different policy preferences. Analyzing bioenergy crop production based on rapeseed, we found that the same level of bioenergy crop production can be achieved at different costs with respect to the other objectives. Overall, we found a tendency to decreased low flow for solutions with higher yields of both rapeseed and food crops, while higher nitrate concentrations were related primarily to increasing yields of rapeseed.