Transportation Bio-Fuels beyond Corn-Ethanol and Fame Biodiesel
Luca Zullo, Cargill, Minneapolis, MN 55440
Corn ethanol has been used in the US as a fuel additive for more than 20 years, but in the last couple of years the industry has entered an unprecedented growth caused by high oil prices, desire for energy sources diversification and changes in the market and regulations for octane enhancers and fuel oxygenates. The FAME (fatty acid methyl esters) industry is following a similar path and the US biodiesel production from soybean oil – from being virtually inexistent – has grown to a sizable industry in just two years. Despite large geographical variations, these trends are largely seen worldwide. In this presentation, it is argued that although valuable, corn to ethanol and FAME biodiesel are transition products and technologies. These fuels are demonstrating the feasibility of renewable fuels for transportation. Yet, because of limits on the supply of feedstock they cannot fulfill but a small part of the demand and are not a long-term approach for the ultimate goal of substantial displacement of fossil fuel consumption. It is impossible to talk coherently about bio-fuels, without considering the whole system from origination of feedstock to ultimate use by the consumer. In turn this realization is driving considerable effort in the technical and economic development of processes to produce ethanol by biochemical conversion of cellulose substrates – in particular agricultural waste of no food or feed value. The biochemical approach to cellulose ethanol is a promising one. It has nonetheless several challenges that require to be evaluated in the context of other possible technological and economic pathways. Some of these pathways may be of particular interest as are based and/or derived from thermochemical processes that are well understood and commonly practiced in today's oil industry. I will review some of these pathways with particular emphasis on the technical aspects and I will discuss why I consider lipids – provided that new non-traditional, non-food sources can be developed – possibly the most desirable platform for the development of bio-fuels. Ultimately, it is very likely that as bio-fuels become a larger component of the world transportation fuel mix, we will rely on a set of solutions based on a variety of technologies and feedstock. Technology and feedstock are not independent variables. Of the possible solutions, the ones that minimize the discontinuities with our current energy infrastructure and reduce the tension on the world food and agricultural land supply are poised to provide the basis for an economically and environmentally sustainable transportation bio-fuel industry.