An examination of biofuels production systems from a resilience perspective

Dongyan Mu, Purdue University


The recent boom and collapse of the corn ethanol industry calls into question the long-term sustainability of biofuels, and traditional approaches to optimization of biofuels production systems. Compared with production of petroleum based transportation fuels, biofuels production is so closely connected and heavily influenced by natural systems that it has to deal with high degrees of complexity, variability, and connectivity within and between systems involved in the entire life cycle of biofuels. As such, unpredictability is an inherent feature of biofuels production. This requires the system to be designed not based on a narrowly defined efficiency, but for resilience (indicated by diversity, efficiency, cohesion and adaptability) to absorb unexpected disruptions and changes. Also, biofuels production systems must be endowed with transformability to allow for “creative destruction” when current fuels are eventually supplanted by new transportation technologies. This dissertation addresses important concepts (i.e., resistance, resilience, adaptability and transformability) in the design of engineered systems that are closely coupled with ecological systems at multiple scales. Several biofuels conversion technologies are examined from a resilience perspective. Multiple technologies should be applied to enhance diversity and flexibility of the entire biofuel industry. Two measures are proposed to examine resilience of biofuels refineries quantitatively. Measure R is based on stability analysis on coefficient of variance (CV) of input and output variables, which addresses engineering resilience (i.e., resistance) of the plant. Measure R' uses net present value (NPV) as an indicator for economic resilience of the plant, which represents an ecological approach to quantify resilience. Strategies are proposed to examine how diverse feedstocks, diverse products and flexible products influence R and R' of a biofuels refinery with the thermo-chemical conversion. Model simulations show that those strategies could improve stability measures (R) by 50%–80% and resilience measures (R') in a wide range of 2% to 140%. Of all strategies discussed, the flexible products have the largest influence on both stability and resilience. To improve resilience, the bio-refinery has to apply multiple strategies into its design. Meanwhile, through controlling characteristics of biomass feedstock and products, the plant could improve its stability and resilience as well.




Zhao, Purdue University.

Subject Area

Alternative Energy|Environmental science

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