(121d) Exergy Analysis for Biofuel Production

Process design has been always an extremely important step in the creation of a new chemical process or plant. The consistent strictness of environmental regulations and continuing need to reduce operating costs has taken a challenge for the design of any chemical process. Exergy is defined as the maximum amount of work that can aid in the design of energy efficient chemical processes and plants. In a chemical process, stream exergy can be composed of three forms; namely material stream exergy, heat exergy and power stream exergy. The main object of exergy analysis is to identify the process steps with a relative exergy loss. Exergy analysis will be useful for design teams to evaluate the process options in detail in order to understand their energy utilization.

Butanol produced from bio-sources (such as corn, rice straw, sugarcane etc) could have attractive properties as a transportation fuel. It can be produced by a fermentation process called acetone-butanol-ethanol (ABE) process. This study investigates biobutanol production processes, including upstream processing, fermentation, gas stripping, and downstream processing (distillation and adsorption for products separation). Biodiesel can be produced from various feedstocks. Exergy analysis is performed based on the exergy efficiency of each main unit in the processes. It will make a positive impact to evaluate the techno-economic feasibility of the whole production system.