9-03: Lifecycle assessment of advanced biofuels - the role of power and chemicals

Within the last two decades there has been increasing development of, and reliance upon, Life Cycle Assessment (LCA) models to assess GHG and other emissions from vehicle and fuel pathways. These models are designed to quantify emissions from the different stages of vehicle and fuel production and use. Since the production of fuels and vehicles involves many possible feedstocks and processes, these models are quite complex; they rely on large and varied sets of input data and they contain assumptions that influence final results.

Advanced biofuels are generally considered to provide superior energy and GHG emission performance over commercial biofuels and petroleum derived fuels. Many models show very large GHG emission reductions for advanced biofuels but some of these were based on early process designs or did not include all of the process inputs into the systems. With the availability of more detailed process data for some advanced biofuels published by the National Renewable Energy Laboratory, more detailed LCA modelling can be performed.

This modelling was undertaken with the GHGenius model and some advanced biofuel pathways were found to be very sensitive to the type and quantity of the process chemicals utilized and to the degree to which surplus electricity can be sold as a co-product. Process developers should consider optimizing their process not only for performance and costs, but also consider the GHG emission performance including all of the process chemicals.