There are many significant drivers for the United States to shift to alternative fuels. These range from reducing our dependency on foreign imports of oils, to the deleterious effects of climate change that are driven by fossil fuels utilization, to creating a new industrial sector (green energy) that will provide high quality jobs for the future work force. There are many routes being explored and touted as alternatives to fossil fuel, including wind, solar, hydrogen, and nuclear energy. One of the more promising possibilities is the development of biofuels from non-edible crops. It would appear that one of the key advantages of biofuels is that conversion of biomass is possible using known technologies such as pyrolysis, hydrolysis, fermentation etc. However, one of the key challenges in this area is that these processes on whole are nonselective. Thus, while the reactor technology for processing raw biomass into a base product feedstock is available, there will be considerable needs for the development of methods for upgrading the base product feedstock. The ability to selectively remove desirable components (e.g. sugars, furfurals) from streams produced by pyrolysis / hydrolysis would represent a simple route to either blending renewable feedstocks into existing fuel production schemes or lead to whole new routes for fuel production. The former represents a logical intermediate target that would be beneficial to the fuels industry meeting government-mandated targets for integration of renewable compounds into the fuel pool. The latter represents the ultimate goal of moving the country away from fossil fuels.
Based on these points, it is believed that new separation schemes will be needed for biofuel utilization to reach its full potential. This workshop will have three major themes:
1. A discussion of the state of the art in feedstock processing, with an emphasis on the nature of the resulting bio-mixtures, particularly focused on properties of relevance for potential separations. 2. A discussion of the current state of liquid separations applied to biofuels processing. 3. A summary session outlining the key and unique challenges facing this area that will lay out a roadmap for future work and goals in the field.
An NSF workshop was held April 4-5, 2011 to review the current status of biofuel production from thermo-catalytic processes and to identify key separations challenges that hinder increased production of biofuels. Approximately 20 scientists from academia, industry, national laboratories and federal funding agencies were in attendance. The attendees agreed that separations play a critical role in biofuel production and that fundamental research, including the identification of transformative approaches, is needed to generate separation technologies that will enable larger-scale production. The workshop generated a report that contained a concise summary of the specific separations challenges that currently exist in thermo-catalytic biofuels production and an associated set of recommendations for fundamental research themes required to meet them. The workshop attendees organized the separations challenges within these four stages of thermo-catalytic biofuel production. • Feedstock treatment prior to conversion • The conversion unit • Product clean up and conditioning • Product upgrading and fuel synthesis Interestingly, some of the key challenges represent general separations problems that would enable biofuels production while others are truly unique to this field. The challenges identified reflect that many of the industrial participants are actively engaged in pyrolysis or catalytic variants of pyrolysis. Efficient and scalable solutions, in terms of materials and processes, do not currently exist for most of the challenges listed above. Many of them represent highly interdisciplinary problems, in that basic science in the area of thermodynamics and fluid mechanics is necessary in order to design the successful separation. Several basic research needs were identified to address the specific separations challenges outlined above. These include: 1. The basic chemistry of oxygenated compounds and its impact on reactivity/transport/equilibrium fluid structure 2. The interactions between oxygenated compounds and interfaces (e.g. emulsions, oxygenate-solid interactions) 3. Molecular-level modeling to determine physical properties of oxygenated compounds 4. Experimental thermodynamic and transport data of oxygenates 5. Thermally and chemically robust and scalable multi-functional materials or hybrid materials to achieve separations 6. Integrated reaction/separation schemes 7. Separations of components from highly dilute mixtures, containing chemically similar species 8. Non-thermal water separations 9. Design schemes for three-phase separations