US DOE Releases Roadmap for Cellulosic Ethanol
7 July 2006
The research agenda focuses on three main areas: better feedstocks, better processes for breaking down cellulosic materials, and optimizing fermentation. Click to enlarge.
The US Department of Energy (DOE) has released a detailed research agenda for the development of cellulosic ethanol as an alternative to gasoline. The 200-page research roadmap—Breaking the Biological Barriers to Cellulosic Ethanol: A Joint Research Agenda—resulted from the Biomass to Biofuels Workshop held in December 2005.
The roadmap identifies the research required for overcoming challenges to the large-scale production of cellulosic ethanol, including maximizing biomass feedstock productivity, developing better processes by which to break down cellulosic materials into sugars, and optimizing the fermentation process to convert sugars to ethanol. Cellulosic ethanol is derived from the fibrous, woody and generally inedible portions of plant matter (biomass).
The roadmap responds directly to the goal recently announced by Secretary of Energy Samuel Bodman of displacing 30% of 2004 transportation fuel consumption with biofuels by 2030. This goal was set in response to the President’s Advanced Energy Initiative.
The focus of the research plan is to use advances in biotechnology developed in the Human Genome Project and continued in the Genomics: GTL program in the Department’s Office of Science to jump-start a new fuel industry the products of which can be transported, stored and distributed with only modest modifications to the existing infrastructure and can fuel many of today’s vehicles.
The December 2005 workshop was hosted jointly by the Office of Biological and Environmental Research in the Office of Science and the Office of the Biomass Program in the Office of Energy Efficiency and Renewable Energy. The success of the plan relies heavily on the continuation of the partnership between the two offices established at that workshop, according to the DOE.
The fundamental barrier to the widespread and cost-effective production of ethanol from cellulosic biomass is the inherent recalcitrance of the biomass to such processing.
Biomass is composed of nature’s most ready energy source, sugars, but they are locked in a complex polymer composite exquisitely created to resist biological and chemical degradation.
Key to energizing a new biofuel industry based on conversion of cellulose (and hemicelluloses) to ethanol is to understand plant cell-wall chemical and physical structures—how they are synthesized and can be deconstructed. With this knowledge, innovative energy crops—plants specifically designed for industrial processing to biofuel—can be developed concurrently with new biology-based treatment and conversion methods.
Recent advances in science and technological capabilities, especially those from the nascent discipline of systems biology, promise to accelerate and enhance this development. Resulting technologies will create a fundamentally new process and biorefinery paradigm that will enable an efficient and economic industry for converting plant biomass to liquid fuels. These key barriers and suggested research strategies to address them are described in this report.
The roadmap lays out a three-stage technical strategy:
The three-stage strategy. Click to enlarge.
Phase 1: Research. This phase, to last no more than five years, is focused on gaining an understanding of existing feedstocks. research will center on the enzymatic breakdown of cellulosic biomass to pentose and hexose sugars (5- and 6-carbon) and lignin using a combination of thermochemical and biological processes. Cofermentation of the sugars will follow.
Phase 2: Deployment. This phase, within 10 years, includes the creation of a new generation of energy crops optimized for sustainability, yield and composition, coupled with processes for the simulataneous breakdown of biomass to sugars and cofermentation of sugars via new biological systems.
Phase 3: Systems Integration. Within 15 years, this phase is to incorporate concurrently engineered energy crops and biorefineries tailored for specific agroecosystems.
Resources:
Breaking the Biological Barriers to Cellulosic Ethanol: A Joint Research Agenda
The Genomics:GTL Biofuels Primer
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