From fields to fuels: A student workshop on conversion of biomass to ethanol

Many biomass materials can be converted into ethanol, with the conversion process varying based on the biological and structural complexity of the material. This process provides multiple opportunities to highlight important principles in biological engineering, with topical, compelling, and relevant exercises for science, technology, engineering and math (STEM) education. In 2009 we piloted a four-day workshop designed to provide hands-on lab experiences with ethanol production from biomass. The workshop was offered as part of a summer camp for high school girls, sponsored by the Penn State Women in the Sciences and Engineering (WISE) Institute. The participants were divided into three groups, each group performing their own experiments with five different materials - sugarcane, paper, corn stover, poplar, and switchgrass. Workshop participants performed the following procedures: (1) hot water pretreatment to alter biomass structure and increase enzyme accessibility, (2) enzymatic hydrolysis to release sugars from cellulose, (3) fermentation to convert sugars to ethanol, and (4) distillation to recover ethanol from the fermentation broth. Ethanol concentrations in the fermentation broth ranged from 8 to 24 g/L, according to sugarcane > switchgrass > paper = stover > poplar. Although the workshop was performed in a laboratory with specialized instruments dedicated to bioenergy research, the workshop could also be conducted in a typical chemistry laboratory with access to an autoclave and distillation column. A workbook was created to document the experimental procedures and to record data and perform calculations related to feedstock supply and ethanol yields. The workshop built on this technical foundation to include analysis of social, ethical, and ecological issues including environmental impacts, food security, and rural development.