Bioethanol–Moving Into the Marketplace Advanced Biotechnology Becoming Reality Technology for producing transportation fuel from biomass is moving out of the laboratory and into the marketplace. In the past decade, advances in biotechnology have allowed us to reduce the projected cost of producing bioethanol from biomass materials other than starches and sugars now used by nearly 25%. In the 1990s, the U.S. Department of Energy (DOE) National Bioethanol Program: ■ Developed new, more versatile, microorganisms capable of squeezing more ethanol from biomass THE BIOFUELS PROGRAM MISSION: Warren Gretz, NREL/PIX 02268 ■ Gained a greater understanding of how the individual technology components work together To develop cost-effective, environ- in an integrated process mentally friendly technologies for ■ Supported the private sector’s initiatives to production of alternative transport- commercialize bioethanol technology ation fuels and fuel additives from plant biomass As we enter the 21st century, we are seeing federal invest- The Biofuels Program is managed by the ment in research beginning to pay dividends in the market- Office of Fuels Development (OFD) at place. Meanwhile, the DOE Bioethanol Program is building the U.S. Department of Energy (DOE). on these successes. Our research program targets process Biofuels research and development Warren Gretz, NREL/PIX 05790 improvements that will ultimately allow bioethanol to includes work on a range of renewable compete head to head with gasoline as a fuel supply for liquid fuels, and covers the whole spec- the U.S. transportation sector. Our strategy is simple. We trum of technology development from basic science to commercial deployment. will ride the growing wave of biotechnology advances to DOE’s Bioethanol Program is by far the build efficient bioprocesses for ethanol production. largest of several fuel development efforts managed by OFD under the auspices of the Biofuels Program. The National Bioethanol road, new energy crops like switchgrass. Today, farmers leave millions of tons of residue on the Warren Gretz, NREL/PIX 03246 Program ground after harvesting corn. The responsible What is biomass? Biomass in- Today, fuel ethanol in the United States is made collection and use of this residue—known as cludes the full range of plant from corn starch, a biopolymer of glucose that corn stover—offers a huge opportunity for and plant-derived materials. is readily broken down to sugars.The goal of expanding the supply of ethanol from its Starches and sugars from the National Bioethanol Program is to develop current level of 1.6 billion gallons per year which ethanol are currently technology which can produce ethanol from (2000) to more than 10 billion gallons per year. made are just a very small the sugars in cellulose and hemicellulose, two As demand expands beyond this level, newly portion of available biomass. of the main components of the fibrous material developed energy crops will come into play. The great bulk of biomass that makes up the bulk of most plants. This consists of cellulose, hemicel- Bioethanol Conversion Technology opens up a wide range of feedstock materials lulose, and lignin. Advanced Two key steps are at the heart of the DOE for bioethanol production to supplement bioethanol technology allows Bioethanol Program’s research and develop- current production from starch. fuel ethanol production from ment activities for bioethanol conversion the cellulose and hemicellu- Biomass Feedstock Development technology: lose, greatly expanding the DOE researchers are developing new sources 1. Hydrolysis. This is a chemical reaction renewable and sustainable of biomass for bioethanol production. These that releases sugars, which are normally resource base available for include the residues left over after harvesting linked together in complex chains. In early fuel ethanol production. of existing food crops and, further down the biomass conversion processes, acids were used to accomplish this. Recent research stand how these organisms handled these has focused on enzyme catalysts called sugars, and to create new organisms capable “cellulases” that can attack these chains of efficient conversion of all the sugars found in more efficiently, leading to very high biomass. With the advent of new tools in the yields of fermentable sugars. emerging field of biotechnology, researchers at DOE labs and at universities across the 2. Fermentation. Microorganisms that country, have succeeded in producing several Min Zhang, NREL/PIX 06812 ferment sugars to ethanol include yeasts new strains of yeast and bacteria that exhibit and bacteria. Research has focused on Zymomonas recognized varying degrees of ability to ferment the full expanding the range and efficiency of the by scientific peers spectrum of available sugars to ethanol. The organisms used to convert sugar to ethanol. advances made in the 1990s are now the 1995—R&D 100 Award starting point for entrepreneurs interested in 1995—Science magazine realizing a new bioethanol industry. Existing publication, “Metabolic ethanol producers are also looking to these Engineering of a Pentose new organisms as a pathway for improving Metabolism Pathway in their own bottom line as well. Ethanologenic Zymomonas mobilis” 1996—U.S. Patent #5,514,583 Hydrolysis Fermentation “Recombinant Zymomonas for pentose fermentation” Bioethanol recycles carbon dioxide 1998—U.S. Patent #5,712,133 “Pentose fermentation by recombinant Zymomonas” Breakthroughs in Fermentation 1998—U.S. Patent #5,726,053 “Recombinant Zymomonas Technology in the Past Decade for pentose fermentation” Lead to Commercialization of 1998—U.S. Patent #5,843,760 Biomass Conversion Technology “Single Zymomonas mobilis strain for xylose and arabi- Common sense suggests that we need to convert nose fermentation” every bit of biomass into fuels and coproducts. For ethanol production, this means using all the available sugars. For most of this century, Warren Gretz, NREL/PIX 00947 researchers assumed that many of the sugars At the Bioethanol Program’s one-ton-per-day Process contained in biomass were not fermentable— Development Unit, bioethanol developers can test those contained in hemicellulose. This meant proposed processes under industrial conditions with- that as much as 25% of the sugars in biomass out having to build their own pilot plants. were out of bounds as far as ethanol produc- tion was concerned. In the 1970s and 80s, microbiologists discovered microbes that could ferment these sugars, albeit slowly and inefficiently. The race was now “on” to under- ADVANCED BIOETHANOL TECHNOLOGY— PROVIDING MULTIPLE OPTIONS The race to create new microbes capable of fermenting Zymomonas, a naturally efficient ethanol-producing the full range of sugars found in biomass has followed bacterium, and added the capability for utilizing multi- several successful pathways. Dr. Lonnie Ingram at the ple sugars (see “Zymomonas recognized by scientific University of Florida started with an E. coli bacterium peers,” above left). capable of metabolizing multiple sugars and added the DOE also helped support Purdue’s Dr. Nancy Ho, who ability to make ethanol—a feat for which he received started with the “industrial workhorse” for ethanol U.S. Patent #5,000,000 in 1990. His work was sponsored production—the yeast Saccharomyces—and added by the Biofuels Program and others. the capability for utilizing multiple sugars. Taking an approach that complements Dr. Ingram’s All three organisms are now being tested by industrial E. coli, other DOE researchers started with the bacterium partners for use in bioethanol production. A Decade of Generating our core Research and Development program with activities focused on near-term deployment Engineering “Know-How” opportunities. Our goal is to plant the seeds today for the technology we are developing Along the continuum of technology develop- for tomorrow’s renewable fuel industry. ment from basic science research to commer- cialization, process engineering data bridges Giving a boost to today’s fuel ethanol the gap between scientific inventions in the industry Today’s ethanol producers are lab and commercial production facilities. The looking for ways to push their yields as high Bioethanol Program, over the past ten years, has as possible. They are turning their attention increased the engineering knowledge base by to corn fiber—the shell of the kernel—as collecting rigorous material and energy balance a source of additional sugars for ethanol data on integrated bioethanol processes. Today, production. But, corn fiber, like other forms Warren Gretz, NREL/PIX 03479 we have greater confidence about projected of biomass, contains sugars that are not process performance and cost, and a far more fermentable by today’s industrial fermentation Current U.S. ethanol realistic understanding of the engineering organisms. The National Corn Growers Asso- producers use only the issues remaining to be solved. This kind of ciation and the Corn Refiners Association are starch in the corn kernels. information is critical to entrepreneurs and working with DOE researchers to tailor new The fiber left from that financiers looking at multimillion-dollar invest- microbes that can ferment these specific processing, however, plus ments in bioethanol technology. sugars. This is work that builds directly off the cobs, husks, and stalks the Bioethanol Program’s successes of the past all contain sugars that can decade. Customized organisms developed in also be made into ethanol. Support for Today’s