“Competing with the scale of the petroleum industry is a real challenge for the biomass economy”
Paul Bryan
“There is money to be made right now in biomass.”
Jeffrey Steiner
Over the past two years, the federal government has released several reports highlighting the importance of biomass as a potential source of economic growth and energy independence. In January 2011, for example, the Congressional Research Service issued a report titled Agriculture-Based Biofuels: Overview and Emerging Issues that reviewed the evolution of the U.S. biofuels sector and the role that federal policy has played in shaping its development. In August, 2011, the Department of Energy (DOE) released 2011 U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry, which detailed U.S. biomass feedstock potential nationwide. The report “examined the nation’s capacity to produce a billion dry tons of biomass resources annually for energy uses without impacting other vital U.S. farm and forest products, such as food, feed, and fiber crops.”2 Then in April 2012, the White House Office of Science and Technology Policy issued the National Bioeconomy Blueprint, a large portion of which described the importance of biomass as a source of energy and chemicals for manufacturing.
To explore the role of the chemical sciences in developing large-scale uses for biomass in the production of fuels, chemicals, heat, and power, the National Academies’ Chemical Sciences Roundtable (CSR) held a workshop on May 31, 2012. Key topics addressed during the workshop included
- The current state of technology in large-scale production of sustainable fuels, chemicals, heat, and power.
- The benefits and weaknesses of current technologies.
- The technical and commercial barriers to scaling up sustainable technologies.
- The optimal ways of combining chemical technologies of different scales to maximize impact.
The workshop began with an introduction by co-chair Paul Bryan, an independent consultant, who reminded the audience that the goal of the workshop was to identify opportunities and obstacles in large-scale biomass production, in general, and ways in which the chemical sciences can further those opportunities and overcome those obstacles. He then reviewed some of the challenges of scale in biomass production, starting with feedstock production, the crop side of this subject. Improving production means increasing biomass yields per acre; decreasing the fertilizer, pesticide, and water inputs; altering plants in a way that makes their conversion to sugars easier; and expanding the range where these crops can be grown. Moving to the chemical or biochemical side of production means improving conversion of harvested biomass into raw materials with increased yield and selectivity; lowering capital costs; and expanding the range of outputs beyond ethanol, biodiesel, and a few other select products.
But even as progress is being made in each of these areas, Bryan said, the supply chain for biomass and its products is only going to be as strong as its weakest link, and today, those weak links include a limited supply of conventional feedstocks; challenges in feedstock harvesting and collection; feedstock transportation and seasonal storage; operating at an efficient scale; and transporting and distributing intermediate and finished fuels and other products. He asked that the workshop participants focus their thinking and conversations on identifying and overcoming these supply chain barriers that represent limits to scaling biomass utilization to a scale
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1The role of the Chemical Sciences Roundtable was limited to planning the workshop, and this workshop summary has been prepared by the workshop rapporteurs as a factual summary of what occurred at the workshop.
2U.S. Department of Energy. U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry. 2011 [online]. [https://bioenergykdf.net/content/billiontonupdate]. Accessed Oct. 9, 2012.
that will address important societal issues regarding sustainability and climate change.
As one example, he discussed the carbohydrate supply chain. Today, if all of the global production of cereal grains were converted to ethanol, leaving nothing for food, the total output would be approximately 14 million barrels of oil equivalent per day. In contrast, current crude oil production is approximately 85 million barrels of oil equivalent per day. Clearly, conventional carbohydrates cannot make a significant impact on the world’s demand for petroleum-based fuels, chemicals, and materials. What can meet that demand is lignocellulose, both from waste and purposefully grown energy crops. Recent estimates from the DOE’s Billion-Ton study put the total U.S. biomass potential of lignocellulose in the range of 1.0 to 1.6 billion tons, which would be enough to meet the demands of the U.S. Renewable Fuels Standards (RFS2) as set out in the Energy Independence and Security Act of 2007 (EISA), and generate enough additional biomass for electricity generation and the production of chemicals and other materials.
Another obstacle is what Bryan calls the tyranny of distance. Although it is expensive to drill a well to collect crude oil or natural gas, a single well produces massive amounts of product that can be fed into a pipeline for distribution. Biomass, in contrast, is sparsely distributed, and even the highest yielding energy crop will require many times the area of an oil or natural gas field to produce the equivalent amount of energy. This will be a challenging problem to solve, one that DOE is addressing through its Uniform Feedstock Format. The idea is that small depots would convert biomass into a uniform, pellet-like material that could be handled as a quasi-liquid and easily transported to central storage or processing facilities. Seasonality is another significant issue, Bryan added, one that will require developing a mix of biomass sources that will together produce a steady supply of feedstock to a processing plant.
There is also the issue of process scale. Today, the world’s largest ethanol plant is rated at 175 million gallons per year, the energy equivalent of approximately 12,000 barrels of oil per day. The largest petroleum refining facility in operation today can process about 1 million barrels of oil per day, and the smallest economically efficient refinery handles 200,000 barrels per day.
After Bryan’s introductory remarks, the workshop consisted of two presentations on feedstocks and conversion technologies, followed by three presentations and corresponding breakout sessions on value chains for the production of fuels, chemicals, heat, and power from biomass. These presentations and discussions are summarized briefly below and in Chapters 2-6 of this workshop report. The workshop concluded with a panel discussion and an open comment period.
Feedstocks and Conversion Technologies
Bryce Stokes, senior advisor with CNJV, a contractor to DOE, summarized the main findings of DOE’s Billion-Ton Study update, for which he was a co-director, noting that the United States has the resources to produce a sufficient supply of renewable biomass to meet its 2030 goal of producing one billion tons of biomass for energy uses without impacting other vital U.S. farm and forest products. The 2011 report included county-level projections showing that necessary land use changes will occur slowly and that a significant amount of biomass will come from increased production of energy crops and increased use of corn stover and straws. The report noted that the woody portion of municipal solid waste can become a substantial contributor to biomass resources. Given the diffuse nature of biomass, collecting and distributing biomass on the billion-ton scale will be challenging. The report also outlines a vision for creating a uniform commodity feedstock from biomass.
Brian Duff, chief engineer and acting deployment team leader for the Office of Biomass Program at DOE, discussed the security, environmental, and economic reasons why the United States should develop biomass-based fuels, chemicals, and power industries. He noted that tapping into the enormous value of petrochemicals and specialty chemicals is a place where chemistry can play a huge role in realizing value from biomass conversion, particularly since these are high value added products that would use very little of the available biomass. He then introduced the two major sets of technologies—biological and thermochemical—for converting biomass into biofuels and chemicals and remarked that the list of building blocks, secondary chemicals, intermediates, and end products that can be made from biomass feedstocks is virtually limitless, just as it is with petroleum.
Value Chains
Chris Somerville, professor of alternative energy and director of the Energy Biosciences Institute at the University of California in Berkeley, gave a broad perspective on the challenges that need to be addressed to develop economically viable schemes for converting lignocellulosic biomass into fuels or intermediates that can be converted into other chemicals. The biggest challenge is to move from the current batch processing system to one that more closely resembles the continuous flow process used in producing fuels from oil. He discussed the potential advantages of continuous flow processing and explained that the development of such a system will require new separation and purification technologies. Attracting researchers with the necessary skills in chemistry and chemical engineering to this field represents a substantial challenge.
Robert Brown, founding director of the Bioeconomy Institute at the Iowa State University, discussed the pros and cons of the two routes for thermochemical conversion of
lignocellulosic biomass into intermediates that would then undergo further processing to produce fuel or chemicals. Gasification, which is well developed for use with coal, produces syngas that can then be converted using chemical catalysts into a variety of fuels and chemicals. Pyrolysis produces charcoal, which can be used as a supplemental fuel for the pyrolysis reactor, or an acidic, oxygenated bio-oil that has the potential to be processed much like petroleum. The chief technical obstacle facing both of these processes is purifying the immediate reaction process of inorganic chemicals that will contaminate subsequent processing steps. While gasification technology is fairly well understood, the same is not true for pyrolysis, and Brown stressed the need for chemists and chemical engineers to study this process, as well as to work on the contamination issue.
Jeffrey Steiner, national program leader for biomass production systems at the U.S. Department of Agriculture (USDA) Agricultural Research Service and agency lead of the USDA Regional Biomass Centers, reviewed the use of biomass to generate heat and power. He noted that the development of a biomass-based power industry in the United States suffers from the lack of a national policy guiding biomass utilization. He also described some of the small-scale systems that are being developed, tested, and deployed for turning biomass into methane that can then be used locally to cogenerate electricity and heat.
General Observations
The final chapter summarizes the panel discussion and compiles some general observations made by the individual workshop participants that apply broadly to the opportunities and obstacles in large-scale biomass utilization and the role of the chemical sciences and engineering in addressing these issues.
ORGANIZATION OF THIS WORKSHOP SUMMARY
This report was prepared by rapporteurs Sheena Siddiqui, Douglas Freidman, and Joe Alper for the Chemical Sciences Roundtable as a factual summary, in chronological order, of what occurred at the workshop. The views contained in the report are those of individual workshop participants and do not necessarily represent the views of all workshop participants, workshop session breakout groups, the planning committee, or the National Research Council. In accordance with the policies of the CSR, the summary does not attempt to establish any conclusions or recommendations about needs and future directions, focusing instead on issues identified by the speakers and workshop participants.
This summary is organized according to the presentations and breakout discussions that were based on three different aspects of the value chains for converting biomass into fuels, chemicals, heat, and power. Overview presentations on the value chains set the stage for breakout sessions that explored the following questions:
1. What is the current state of technology in large-scale production of sustainable fuels and chemicals?
a. How can we best combine chemical technologies of different scales to maximize impact?
b. How can we identify ways in which technologies of different practical scales can complement each other?
2. What are the technologies and commercial barriers to scaling up sustainable technologies?
3. What skills will chemists and chemical engineers need to enable a growing biomass economy that are not widely held and/or taught today?
4. Where can we exploit existing transportation infrastructure to meet the new needs, and where must we build new infrastructure?
In trying to make the workshop material readily available to the public, the Board on Chemical Sciences and Technology developed a hub for information relating to the Opportunities and Obstacles in Large-Scale Biomass Utilization: The Role of the Chemical Sciences and Engineering workshop. At the time of this publication, additional material relating to the workshop could be found at http://dels.nas.edu/global/bcst/biomass. It includes speaker PDF presentations and presentation recordings, and breakout session summary slides.
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