NREL's biofuels manager outlines agency goals

Target for cellulosic ethanol is to have technology sufficiently developed to support one or more commercial-scale plants by 2010.'
By | September 01, 2002
Cindy Riley, P.E., is Biofuels Program Technology Manager at the National Renewable Energy Laboratory (NREL). Riley has a broad range of experience in the energy and enviromental industries with expertise in the technical and economic analysis of emerging alternative energy technologies. She has more thean 24 years of experience, including alternative energy research with Exxon, process design engineering with Fluor and Raytheon, and research engineering and management with NREL. Riley has been with NREL for 12 years.

EPM: Is it possible to prioritize - or rank - the importance of ethanol-related research and development that NREL is currently involved in? If so, please give EPM readers an idea of what type of ethanol-related R&D is taking center stage at NREL in 2002-2003, and what research may becoming less of a priority.

Riley: The primary objective of the DOE Biofuels Program is to develop technology for economically producing ethanol and other fuels, chemicals, and materials from lignocellulosic biomass. At the same time, we strive to work closely with the existing grain ethanol industry to increase ethanol yields per bushel. To this end we work on both improving starch-to-ethanol technology and developing technologies for ethanol production from the remaining carbohydrates in fiber and DDGS, including cellulose and hemicellulose. DOE and NREL are devoting considerable resources to lower the cost of conversion of lignocellulosic biomass into sugars as intermediates for production of ethanol as well as other chemicals. We are focusing on corn stover, a resource readily accessible to existing ethanol producers, as a model agricultural residue and the most likely first large-scale cellulosic feedstock. Chief among our R&D efforts has been DOE's cost-shared contracts with Novozymes Biotech and Genencor International to dramatically reduce the cost of cellulases, the enzymes that help break apart the tightly bound cellulose polymers. NREL is providing technical and analytic assistance to the enzyme producers. In the next two years, we hope to have cellulases that are 1/10 the cost of those available in 2001. We are also working hard at optimizing and integrating our pretreatment and fermentation systems to achieve continuous high yields of both C-5 and C-6 sugars from corn stover. We have been devoting fewer resources to feedstock research, in part because the USDA is expanding its work in that area.

EPM: It's well known that NREL often works with both public and private groups - including national laboratories, universities and private industries - on a wide array of research and development. How important are these partnerships to NREL's mission and accomplishments? What kind of partnerships can we expect to see in the coming years?

Riley: Partnerships have always been very important for NREL and DOE in the area of biofuels and that importance is increasing. On the basic research side, we work closely with universities and other DOE laboratories and USDA research centers to better understand biomass production and conversion processes. Cost-shared partnerships with private industry are absolutely essential to enabling the commercialization of biofuels technologies. The primary role of the DOE Biofuels Program is to conduct the relatively high risk R&D that, once accomplished, will sufficiently reduce the technical and business risks for private companies to be willing to invest in the later and even more costly stages of demonstration and commercialization. Cost shared partnerships allow DOE to leverage its limited funds, while at the same time enabling more direct technology transfer to the private sector which hopefully results in more rapid commercialization. In the future we expect to see more partnerships with established dry and wet mill firms, as well as fuels and chemical producers who are trying to move from petroleum-based to biobased feedstocks.

EPM: One of NREL/Biofuels Program's primary functions is to research cellulose-to-ethanol processes and advance cellulase enzyme research. How would you categorize the state of cellulose-to-ethanol R&D at NREL? How far has the research come from just a few years ago? Is NREL making any predictions of its own about when cellulosic ethanol will become commercially viable on a large-scale basis?

Riley: We have now clearly demonstrated effective technology for all phases of the cellulosic biomass-to-ethanol process. The challenge from here out is to bring the cost of the technology (largely a function of high capital equipment cost) down to levels where private industry will be interested in moving forward building commercial facilities. Recent innovations in pretreatment systems, enzymes, and fermenting organisms should make important contributions. The DOE target for cellulosic ethanol is to have technology sufficiently developed to support one or more commercial-scale plants built and operating by 2010.

EPM: Is NREL currently operating a biomass-ethanol pilot plant, or involved with
any such plant(s)? Where? In what capacity?

On our Golden campus, we operate a 1-ton per day (dry feedstock basis) process development unit, officially known as the DOE Bioethanol Pilot Plant. The Alternative Fuels User Facility or AFUF, which includes the pilot plant and other research facilities was specifically created to provide a national center where interested companies and researchers could test out various processes for converting cellulosic feedstocks to ethanol or value-added products without having to invest in their own pilot plant. For example, our pretreatment reactors are designed to safely operate with relatively high acid or base concentrations and elevated temperatures. The pilot plant is certified to safely handle recombinant organisms. All equipment is fully instrumented with more than 900 data acquisition points and can be operated at various levels of process integration. This flexibility allows our partners to quickly test various combinations of operating conditions to determine what works best for their particular feedstock, enzyme cocktail, and/or fermentative organism.

EPM: In your own words, why is the research and development conducted by NREL important to the ethanol industry? Why should, say, a general manager of a corn-ethanol plant in Iowa be concerned about what NREL is working on today? How does the research affect the ethanol industry at its basic commercial level?

What NREL is working on today, the Iowa grain-ethanol plant (or his competitor) may be using in the near future. The carbohydrates that now remain in co-product animal feeds are a clear market opportunity for cellulosic ethanol production: more ethanol and higher-protein animal feed products. Also, the corn grain resource does have limits. As ethanol production increases sharply in the next eight years to replace MTBE and to meet rising demand for octane and oxygenates, there will likely be upward pressure on grain prices. The cost of the feedstock for a corn-based ethanol plant will rise, possibly squeezing profit margins. In the short run, we are working with existing ethanol plants to get higher ethanol yields per bushel, as well as investigating ways to upgrade fiber and DDG to get higher prices or to enter new animal feeding markets. In the long run, we are focused on the research that will allow future plants to produce ethanol at a price competitive with gasoline without subsidies. This will require less expensive feedstocks and highly efficient, cost-effective conversion processes. With their existing capital equipment, infrastructure, expertise, and access to cellulosic resources such as corn stover, corn-ethanol plant operators are well positioned to also produce ethanol from lignocellulosic biomass.

EPM: Explain the concept of the biorefinery. What is it, and what should it mean to existing and future ethanol producers?

Riley: The term biorefinery is derived, as you can guess, from the petroleum refinery. However, renewable, domestic biomass is the feedstock instead of crude oil. The key to the biorefinery concept is flexibility. The biorefinery facility will be designed to process a diverse set of feedstocks, determined largely by its specific location, and produce a slate of intermediate and end products, not just one or two. To continue the petroleum refinery analogy, petroleum refineries typically produce more gasoline in the late spring and summer, when demand and prices are highest, and less of other refined products. Future biorefineries are expected to be able to handle a changing mixture of incoming feedstocks and to maximize revenue by producing a variety of high-value products (chemicals, materials) in addition to fuels and animal feeds. For the ethanol producer, it will mean less volatility in income as corn or milo prices rise and fall. The biorefinery may substitute agricultural residues for some of its grain feedstock when corn prices rise and adjust its product slate accoringly. In DOE's efforts to create successful biorefineries we emphasize taking maximum advantage of available feedstocks and conversion technologies to produce a range of products from high-value/low-volume chemicals and materials to high-volume/low-value fuels. High-value bioproducts may catch market excitement in the near term but large volumes of fuels are what the country needs to reduce our dependence on foreign oil and improve the environment.

EPM: In your view, what is the most promising emerging biomass-to-ethanol conversion processes being developed today?

Riley: In order for DOE to achieve its long-term target of ethanol competitive with gasoline we have recently renewed emphasis on understanding the fundamental science, especially the chemistry, of biomass and its conversion to sugar intermediates at high efficiency and low cost. The core lignocellulosic biomass-to-ethanol technology elements for the Biofuels Program include dilute-acid pretreatment to hydrolyze hemicellulose, enzymes to hydrolyze cellulose, and co-fermentation of C-5 and C-6 sugars. We are currently examining the full range of pretreatment technologies being researched around the world to identify those that have the most potential to meet the technical and cost targets needed by biorefineries in the future. We are also looking at a variety of hydrolysis and fermentation strategies to take advantage of the full complement of sugars derived from biomass and their different product opportunities. Biotechnology advances are enabling rapid progress in this area.

EPM: What scientific and/or production process developments originating from NREL/DOE can the ethanol industry expect in the next five years?

Riley: Pretreatment of corn fiber and DDG to extract additional ethanol and to upgrade co-products has shown great promise and should enter the mainstream ethanol industry within the next few years. Our experience in process chemistry and chemical analysis of complex carbohydrate streams high may also prove useful as existing plants seek to increase their throughput, ethanol yield, and plant efficiency. Several companies are interested in using fermentative organisms that we have developed. We expect major cost reductions in cellulase enzymes and therefore cellulosic ethanol to come from our contracts with Genencor International and Novozymes Biotech.

EPM: Last question: What's your evaluation of the commercial ethanol industry today? Is it hindering the advancement of commercially viable biomass conversion to ethanol, or advancing the sci-ence? Other thoughts?

Riley: The commercial ethanol industry of today, based on starch feedstocks, is laying the groundwork for the ethanol industry of tomorrow, which will use lignocellulosic as well as starch feedstocks. Perhaps most importantly, the current ethanol industry is developing the market and infrastructure for the future expanded industry. Also, as discussed above, the players in the current industry can easily be important players in the future. The commercial ethanol industry is in the midst of a major transition today, due to recent construction of numerous large (40 million gallons per year or more), highly efficient dry mills. Advances in understanding the complex chemistry of corn milling operations and exploiting opportunities identified through this deeper understanding should lead to a technological shift where dry mills will begin to take on some of the characteristics of biorefineries by adding capability that allows them to produce high value products (germ, oils, nutraceuticals) in addition to ethanol and animal feed. We also expect existing mills to become the testing ground for cellulosic biomass conversion, initially using corn fiber and DDG as their feedstocks and later integrating dedicated feedstocks such as corn stover. This will serve as the bridge to a dramatically expanded ethanol future.