A Case Study Investigating the Environmental Impact of Pelleting in Cellulosic Biofuel Manufacturing

Cellulosic biofuel manufacturing consists of two major processes, biomass feedstock preprocessing and bioconversion. Traditionally, these two processes are conducted in different locations in practice and transportation is required to connect the two processes. Pelleting in preprocessing can help reduce the size and increase the density of biomass so that the transportation and handling can be more efficient. However, pelleting is also considered an energy-intensive process that consumes a large amount of energy, which leads to considerable greenhouse gas emissions. Due to such an environmental and energy related concern, the use of pelleting process in real industry is still in doubt regarding its performance of environmental sustainability although it has been extensively studied in laboratory scale. In this paper, we analyze both positive and negative impacts of pelleting in biofuel manufacturing regarding GHG emissions. A numerical case study focusing on the transportation is conducted to examine such impacts through the comparison between the scenarios with and without pelleting process to estimate the net emission due to the pelleting process.