Biofuels Technology Roadmap

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First generation biofuels technologies comprise mainly of fuel ethanol from crops such as corn and sugarcane and biodiesel from crops such as rapeseed and soy. Second generation processes are those that produce energyefficient biofuels that do not compete with the food chain for feedstocks. Secondgeneration processes convert lignocellulosic materials, including agricultural and forest residues such as corn stover, rice straw, wheat straw, and bagasse and possible nonfood bioenergy crops such as switchgrass, poplar, and Miscanthus grass (elephant grass). Cellulosic ethanol technology is still a few years away from economic viability. There are two alternative types of technology platforms:

(a) a biochemical or sugar platform depending on acid or enzymatic hydrolysis of lignocellulose to sugars with subsequent fermentation to ethanol; and (b) a thermochemical platform using gasification of biomass to syngas with subsequent fermentation or catalytic conversion to alcohols.

Biodiesel is another biofuel seeing rapid growth worldwide. Feedstocks include plant-derived oils such as rapeseed, soy, and palm oil, as well as waste oils. Jatropha, a weed that grows in arid climates, is also gaining support in India and some other locations. Conventional biodiesel processing often converts less than 10% of the mass of dried plants, so a clear need exists for more efficient biodiesel technologies. Choren Industries GmbH (Freiberg, Germany) is developing a new biomass-to-liquids (BTL) technology that involves high-temperature gasification of biomass followed by a catalytic Fischer Tropsch process to make a high-cetane synthetic biodiesel. Algae are a potentially rich source of biofuels and an area of intense interest today. Significant potential exists for cultivating high-oil-content, high-growth microalgae containing more than 50% oil for conversion to biodiesel. Algae can grow on marginal land or in water so as not to compete with food crops.

New biofuels are also under development. Biobutanol is attracting the attention of a number of companies because it has some key advantages over ethanol, including higher energy content and better transport characteristics. BP Biofuels is progressing a near-term effort with DuPont to develop and commercialize biobutanol. The biobutanol-fermentation process initially will use DuPont’s biocatalyst and bioprocess technology using locally grown sugar beets. BP and DuPont are working on the development of a second-generation process using a more-targeted biocatalyst and the ability to process lignocellulosic Feedstocks.

Future breakthroughs in cellulosic-ethanol production and entirely new biofuels may come from the field of synthetic biology. Several start-up companies are using synthetic biology techniques to make renewable hydrocarbon fuels that are very similar to today’s petroleum fuels and are thus completely compatible with existing fuel infrastructures. Researchers are engineering microbes by incorporating genetic pathways from other microbes, plants, and animals.

Synthetic Genomics (Rockville, Maryland), founded by biotechnology pioneer Craig Venter, is trying to produce a highly engineered “synthetic organism” that can perform multiple tasks well: efficiently break down cellulose like a bacterium, ferment sugar like a yeast, and tolerate high levels of ethanol. Hoping to improve on the attributes of ethanol fuel, start-up companies Amyris Biotechnologies, Inc. (Emeryville, California), and LS9, Inc. (San Carlos, California), are both targeting the custom-designed fuels arena. Amyris is focusing on advanced diesel and jet-fuel formulations; LS9’s focus is on jet fuel, low-sulfur gasoline biofuels, and specialty biochemicals. Although still early stage, the companies hope to bring these products to market within four or five years. Technology challenges include the massive scale-up necessary to produce the new biofuels in large volumes.

A growing number of bio-based chemicals, such as the biodegradable bioplastic PLA (polylactic acid) that derives from corn, are already in commercial production, and several additional products will reach commercialization in the next few years. The longer-term plan is to use lower-cost lignocellulosic feedstocks in stand-alone plants or future integrated biorefineries. Production of high-value chemical building blocks and biopolymers is key to the success of biorefineries.

For biochemical-conversion technologies, a major R&D focus is on improving pretreatment technology for breaking hemicellulose down to component sugars and developing more cost-effective cellulase enzymes (biocatalysts) for breaking cellulose down to its component sugar. Another key enabling technology is the engineering of microorganisms and enzymes that can efficiently convert the complex cellulosic wastes to simple sugars and then to ethanol or chemical building blocks. Lignocellulosic feedstocks contain both five-carbon pentose sugars (D-xylose and L-arabinose) and six-carbon sugars (glucose, mannose, and galactose). Cost-effective processes need to ferment all five sugars rapidly, but the pentoses in particular are not easily metabolized by common yeasts in use for ethanol production today. For thermochemical-conversion technologies, much of the current R&D is on syngas production and use to make fuels and other valuable products. Technology developers are also working to demonstrate their integrated conversion processes in real-world applications in rural areas.

Rising prices for crops such as corn, sugar, wheat, and oilseeds and inadequate infrastructure are serious impediments to the wholesale adoption of first-generation biofuels. The development and implementation of new lignocellulose conversion and biorefinery technologies could enable a range of new biofuel and bio-based chemical products that are fully cost competitive (without government subsidies) with conventional petroleum-based fuels and products beginning in the 2010 to 2015 timeframe. Future biofuels and bioproducts may also offer improved performance and environmental attributes, including Biodegradability.

A large-scale bioenergy economy will rely on technologies such as genetic engineering and agricultural practices to help increase biomass yields and lower cultivation costs. Harvesting crops, collecting biomass residues, and storing and transporting biomass resources are critical aspects of the biomass-resource supply chain. Biomass handling systems are also important—they can represent a significant portion of the capital and operating costs of a biomass conversion facility. For example, rice straw is very fibrous and can be difficult to process. New integrated biorefinery technology requires new bioprocessing techniques and lower-cost separation methods in addition to improved biocatalysts. The design of bioreactors is another important area of research to allow maximum process Efficiency.

Integrated biorefineries based on waste agricultural and other lignocellulosic biomass feedstocks will use locally available resources to produce biofuels and other bio-based products. The six biorefinery demonstration plants that the Department of Energy is co-funding illustrate a range of locations and approaches:

Abengoa Bioenergy (Chesterfield, Missouri) will operate a facility in Kansas to process 700 tons per day (tpd) of corn stover, wheat straw, switchgrass, and other feedstocks to produce 11.4 million gallons per year of cellulosic ethanol and syngas for energy.

Alico Inc. (LaBelle, Florida) will turn 770 tpd of yard, wood, and vegetative wastes such as citrus peel into 13.9 million gallons per year of cellulosic ethanol, 6,255 kW power, 50 tpd ammonia, and 8.8 tpd hydrogen. BlueFire Ethanol, Inc. (Irvine, California), will convert 700 tpd of sorted green waste and wood waste from an urban landfill in Southern California to produce 24 million gallons per year of cellulosic ethanol.

Poet Design & Construction (Sioux Falls, South Dakota) will convert an existing ethanol facility in Iowa to a biorefinery processing 842 tpd of corn fiber and stover to produce 26.4 million gallons per year of cellulosic Ethanol.

Iogen Biorefinery Partners, LLC (Arlington, Virginia), will operate a biorefinery in Idaho to convert 700 tpd of wheat straw, barley straw, corn stover, switchgrass, and rice straw to produce 18 million gallons per year of cellulosic ethanol.

Range Fuels Inc. (Broomfield, Colorado) will operate a plant in Georgia to convert 1,200 tpd of woody residues and energy crops to produce some 40 million gallons per year of ethanol and 9 million gallons per year of Methanol.

Source: Biofuels and Bio-Based Chemicals, Global Trends 2025, SRI Consulting Business Intelligence, 2008.

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