In addition, the RFI requests stakeholders to contribute their views and opinions regarding the draft Conversion Technologies for Advanced Biofuels (CTAB) Roadmap developed as a result of the DOE CTAB road-mapping workshop held in December 2011.

The objective of the CTAB workshop was to provide the DOE Office of the Biomass Program (OBP) input necessary to update its existing technology roadmaps in terms of pathways for the production of transportation fuels (i.e., gasoline, diesel, and jet fuel) from lignocellulosic materials. The new Roadmap is intended to highlight existing and potential research barriers in the commercial development of technologies that are necessary to generate carbohydrate and bio-oil intermediates from biomass and upgrade those intermediates to drop-in replacements for gasoline, diesel, and jet fuel.

During the CTAB workshop, a multitude of biochemical, catalytic, and thermochemical conversion strategies were discussed. A draft CTAB Roadmap accompanying the RFI compiled the topics and outcomes discussed during the 3-day meeting, which was attended by nearly 150 stakeholders and subject matter experts from industry, academia, and the national laboratories.

In addition to identifying key technical barriers and research and development activities, workshop participants also addressed feedstock supply, logistics considerations, and fuel blending requirements. Other innovative topics were addressed in special sessions, including the utilization of lignin, hybrid biochemical/thermochemical processing routes, solvent and separation systems, and processing of genetically modified biomass feedstocks.

During the CTAB workshop, participants in all sessions consistently identified four overall cross-cutting themes which commonly manifested in the form of technical limitations in most (if not all) biomass conversion processes:

1. Feedstock Pre-Processing. Feedstock pre-processing is important for delivering consistent, predictable lignocellulosic material to the reactor throat. Various downstream processing configurations across thermochemical, biochemical, and catalytic systems are often optimized based on narrow feedstock specifications, and inefficiencies can arise if these specifications cannot be met.

2. Efficiency in Catalysis and Biocatalysis. Catalysts and biocatalysts (enzymes and microorganisms) are often fine-tuned to work on singular or highly uniform substrates, and inasmuch, often need modification to behave robustly in heterogeneous and non-uniform process streams derived from biomass. Poisoning of catalysts and biocatalysts is often exacerbated in biomass processing technologies, and catalyst carbon efficiency is typically a parameter which is sought to be maximized.

3. Separation Science. In general, conversion technologies involve multiple steps and require several separation techniques for isolating desired products in complex mixtures. Separation technologies tend to be specific to the feedstocks, products, biomass derived process streams, and the conversion technologies associated with them. Therefore, separation sciences represent a wide-reaching area which covers a variety of technology forms, from distillation to membrane systems, and can be classified based on the types and concentrations of species, solvents, and reaction conditions. Intermediates and products may have significantly different purity requirements depending on subsequent processing requirements. Separation can quickly become a cost prohibitive unit operation within a process; therefore it is important to carefully define the cost/benefit trade offs.

4. Process Data to Generate Techno-Economic Models. Techno-economic analysis (TEA) couples process design and cost analysis with experimental and pilot scale research results to evaluate the current economic state of technology of a process. Early scoping studies that include economics can help to identify unknowns and uncertainties in processes that need additional experimental investigation and quantification. TEA can also serve to develop an understanding of how process economics relate to experimental research developments and process improvements. In this context, TEA is a powerful tool that can be utilized to develop a cost-driven research and development program.

Resources

• Draft Conversion Technologies for Advanced Biofuels Preliminary Roadmap & Workshop Report