Realizing the Potential of Advanced Biofuels
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Advanced biofuels or drop-in fuels is the terminology used to refer to hydrocarbon fuels that are direct replacements or supplements for existing gasoline, diesel and jet fuels currently refined from conventional petroleum feedstocks. Drop-in fuels from biomass will need to meet all of the refinery and ASTM specifications for any blending ratio up and including 100% to truly qualify as drop-in fuels. Achieving this will ensure complete infrastructure compatibility and thus these drop-in biofuels will have a streamlined path to market by not facing the infrastructure compatibility limitations of current biofuels such as ethanol or biodiesel. This accelerated path to market by utilizing the existing infrastructure will minimize the amount of greenfield capital investments that will be required. Hence these market advantages afford drop-in biofuels the ability to contribute as rapidly as possible to the national objectives of increased U.S. energy security, reduced greenhouse gas emissions and a more diverse environmentally sustainable transportation fuel supply.
The objective of the National Advanced Biofuels Consortium (NABC) is to develop cost-effective technologies for advanced drop-in biofuels that are compatible with today's transportation infrastructure and are produced in a sustainable manner. Our overarching goal is to expedite transfer of the resulting biofuel technology to industrial practice, in order to contribute as rapidly as possible to the national objectives.
The most effective means to meet these critical national objectives is to supplement petroleum at the refinery gate. This will avoid the costs of new infrastructure and accelerate broad utilization of biofuels by the existing transportation fleet. However, the chemical and physical complexity of biomass has prevented its use as a refinery feed. As a consequence, the primary source of biofuels to-date has been fermentation of starch (corn) to ethanol, which has two fundamental challenges: 1) competition with food/feed supply, and 2) inability to take full advantage of existing infrastructure. Cellulosic-based ethanol mitigates the food/feed supply competition but does not address the second fundamental challenge full infrastructure compatibility. Hence it faces the same market growth limitations, such as blend wall, low energy density and limited applicability for diesel and jet use. The objective of this project is to develop one or more biofuel technologies that address both these fundamental challenges and thus take full advantage of the cost savings that are possible by use of existing refineries, distribution networks and vehicle fleets using high impact lignocellulosic feedstocks.
To achieve this objective, the NABC team evaluated the petroleum refinery and its potential to accept biomass. Key barriers to introducing biomass into a refinery are that it is solid, heterogeneous, and has high oxygen content. A successful technology must reduce oxygen content, improve miscibility with petroleum, and minimize critical contaminants that can poison catalysts. We identified three plausible refinery insertion points (Figure 1). For insertion point one (In Pt 1), biomass is converted to a bio-crude that can be co-processed with conventional crude oil. For insertion point two (In Pt 2), biomass is upgraded into refinery-ready intermediates that have properties compatible with refinery streams, which will then be further, co-processed. The third insertion point (In Pt 3) is a near-finished fuel or blendstock that could take advantage of the refinery for minimal processing (e.g. hydrotreating, isomerization). We then performed a systematic evaluation of a broad spectrum of biomass processing pathways consistent with the identified insertion points. Based on a number of criteria such as sustainability, economic and process viability, diversity of approach and commercialization potential we chose the most promising next generation process strategies. We also identified specific barriers to commercialization within each strategy associated with the use of high impact lignocellulosic feedstocks. The selection process was carried out in a series of meetings that included biofuels experts from the petroleum industry, national labs, and academia. These six process strategies provide a broad and robust suite of technologies to maximize the production of biofuels from the physically and chemically diverse range of lignocellulosic feedstocks that are projected to be available on a sustainable basis in the future. These process strategies provide technical diversity and flexibility with respect to refinery insertion points. The diversity of process strategies helps mitigate project risks, provides an opportunity to examine the relative merits of alternative process strategies and promotes synergies among technologies.
The NABC team members were chosen based on two criteria: 1) world-class expertise to pro vide full coverage of the entire value chain from feedstock to fuel and 2) technical expertise and background intellectual property in areas relevant to the six process strategies. Developing the team along these lines has allowed us to assemble a consortium fully able to achieve the objectives of the project and the FOA. The industrial partners include 1) refiners BP, Tesoro, 2) technology developers UOP (with USDA-ARS and Ensyn as subcontractors), Amyris, Virent, Albemarle, RTI, 3) a separation expert Pall, and 4) a feedstock technology developer Catchlight Energy. The university partners, Colorado School of Mines, Iowa State University (with Northwestern as a subcontractor), University of California at Davis and Washington State University bring expertise in bioprocessing, catalysis, and mechanistic and kinetic modeling. The National Laboratories NREL, PNNL, ANL, and LANL bring top experts in biofuels, including bioprocessing, catalysis, computational modeling and engineering and sustainability analysis.
Through novel catalytic and fermentative approaches the NABC will transform biomass into a form that is suitable for insertion into the current refinery and distribution infrastructure. The research program will be conducted in two stages. In Stage 1, targeted research will be done to address our abilities to overcome the key barriers within a three-year project for each strategy. At the conclusion of Stage 1 we will down-select from the six process strategies and identify one to three most likely to succeed. The down-select criteria include technical, economic, and environmental metrics. Research in Stage 2 will focus on science and engineering activities to integrate the selected processes into the refining infrastructure. Underpinning all that we do will be a robust sustainability and technoeconomic analysis (TEA) function to ensure that we are selecting and developing only those pathways that will be competitive and sustainable. At the conclusion of the NABC, we will deliver a pilot-ready process, a detailed design report, and a life cycle analysis.
In summary, displacing oil at the refinery gate avoids cost in new infrastructure and increases the rate of broad deployment into the existing fleet. This approach provides a cost-effective way to supplement the existing market with drop-in fuels made from biomass, and achieve the goals of enhancing U.S. energy security, reducing greenhouse gas emissions and creating economic opportunities across the nation. This is the objective of the research of the NABC.