Reducing the cost, environmental impact and energy consumption of biofuel processes through heat integration

This study proposes a process design methodology based on the combined use of process simulation in Super Pro Designer with economic, environmental and energetic balances implemented in Matlab and heat integration using Aspen Energy Analyzer. We model a 2.4 MMgal/year alkali-catalyzed biodiesel process using vegetable oil and a 40 MMgal/year dry-grind corn based bioethanol production plant. Then, we analyse the cost, the environmental impact, and the energy required to produce one gallon of the desired biofuel. Finally, we determine the optimal heat integration strategy of the plant in order to reduce the cost, environmental impact and energy consumption associated to the biofuel production. In the case of biodiesel the cost is reduced from 2.27 $/gal to 2.19 $/gal, the environmental impact from 4.52 kgCO2eq/gallon to 4.26 kgCO2eq/gallon and the energy from 8274 BTU/gal to 8410 BTU/gal. Reductions are also obtained in the bioethanol plant in which the cost is reduced from 1.79 $/gal to 1.75 $/gal, the environmental impact from 4.97 kgCO2eq/gal to 4.77 kgCO2eq/gal and the energy from 24,681 BTU/gal to 23,168 BTU/gal.