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Transforming Combustion Research Through Cyberinfrastructure 1 Introduction Combustion has provided society with most of its energy needs for millennia, from igniting the fires of cave dwellers to propelling the rockets that traveled to the Moon. As newly emerging world economies grow, their energy needs are being met by combustion systems, particularly those burning coal and petroleum-based fuels. Today, the world faces a crisis involving the need to make trade-offs between the ever-increasing energy demands of a growing world and the harmful environmental impacts of chemical pollutant emissions and global warming from greenhouse gases, especially carbon dioxide (CO2). Science and engineering can help resolve this crisis in many ways, which include improving and replacing today’s combustion systems—fossil fuels and biofuels and the systems that extract their energy—to make combustion more efficient and/or cleaner. The pace of developing such improvements or new systems is slower than it need be. A community-wide cyberinfrastructure (CI) that addressed the needs of combustion research and development (R&D) for the timely sharing of data and more powerful simulation capabilities would speed up innovation in all aspects of combustion science and engineering. Software tools, computing and communication hardware, and specialized personnel together would form this critical tool that would enable the delivery of the new technologies that can help resolve this global crisis. Hydrocarbon fuels and combustion have dominated the world’s energy picture for centuries. Coal enabled the industrial revolution and continues to be a major energy source; coal-fired power plants are being
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Transforming Combustion Research Through Cyberinfrastructure built at a dramatic rate today in China (U.S. EIA, 2006) and their emissions are a worldwide concern. Petroleum-based liquid fuels have dominated transportation fuels since the late 1800s, but some estimates suggest that only about a 50- to 100-year supply is left (U.S. EIA, 2007b). The availability of these fossil fuels and their geographical distribution around the world have had profound effects on international politics and economics, as well as enormous impacts on lifestyles everywhere by affecting where and how people live and work. Wars have been fought over access to petroleum and other fossil fuel resources, and growing pressures for energy may again lead to serious international conflicts.1 Fossil fuels will not last forever, but it is likely that they will continue to be a primary source of energy worldwide for years to come. There is no alternative energy technology that can replace combustion now, either with respect to the costs of supply or to the total capacity to provide for the huge energy needs of modern society. As fossil fuels diminish, they are likely to be at least partially replaced by other combustion fuels such as ethanol and biodiesel fuels. Energy production technologies change slowly, over decades, because of the enormous investments involved. Time is short, as combustion CO2 emissions continue to grow explosively, potentially increasing the rate of global climate change that is taking place. All of this makes it essential to revolutionize the ways in which the combustion of these conventional fuels and that of new alternative fuels are achieved; incremental advances will not suffice. As new carbon-neutral fuels are developed, there will be a need to understand how they burn and impact combustion-based engineered systems. The Committee on Building Cyberinfrastructure for Combustion Research believes that a community-wide CI, as presented in Chapter 2, would fuel the transformation that will accelerate the progress in combustion research and development. This transformation will be accomplished through the effective exchange of information, data, and software tools among the various subdisciplines and organizations that form the combustion community, as well as through advances in predictive capabilities that leverage state-of-the-art computer simulations and computing power. ALTERNATIVE ENERGY SOURCES An emerging “green revolution” in energy provides some optimism for the partial replacement of fossil fuels by renewable energy sources in the coming years. Wind power and solar power are growing rapidly and may eventually become significant sources of energy, and hydroelectric 1 The role of the need for oil as a cause of war is widely documented. See, in particular, Heinberg (2003).
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Transforming Combustion Research Through Cyberinfrastructure power has long been a significant part of the U.S. energy supply. However, there are limited opportunities to develop new major hydroelectric sources, and wind and solar power technologies require massive capital investment that makes them unlikely to compete on a large scale with fossil fuels for many years without large subsidies, tax, or regulatory advantages. At present, fossil fuels are much more economical than either wind or solar energy on a per kilowatt-hour basis (U.S. EIA, 2007a). Wind and solar power also have the disadvantage of being intermittent and are not necessarily well matched to conventional energy demands, so some sort of energy storage revolution would be necessary for them to become major contributors to meeting to the world’s energy needs. Renewable fuels for combustion systems for both propulsion and power generation represent another alternative, and many available options are being studied. Although existing commercial biofuels made from food are likely to provide only up to about 10 percent of total U.S. fuel requirements (U.S. EIA, 2007a), significantly larger amounts could potentially be produced using waste biomass (Perlak et al., 2005), with much less impact on land use and food prices; a large R&D effort is already under way to develop cost-effective methods for making new biofuels from this unused resource. There is also considerable research being conducted into even more novel methods for producing alternative fuels—for example, from bio-engineered algae (Sheehan et al., 1998). The introduction of any alternative fuels to the market in large quantities is likely to require modifications both to the engines and to the raw biofuels in order to optimize the system, and so significant new combustion R&D efforts would be required. In the long term, there are many possible energy sources that could eventually displace fossil fuels, and most of these are being studied seriously. They include nuclear and thermonuclear power production. Although attractive, these options are likely to require very lengthy development times. The needs of power and transportation systems, especially aircraft, will very likely require liquid hydrocarbon fuels for years to come, as the power densities required for flight are high and, at present, cannot be satisfied in any other obvious way. Even after the world has consumed all of its naturally occurring liquid hydrocarbon fuels, there will remain a need to produce such fuels to power aircraft, probably by means of the Fischer-Tropsch2 or the biofuel production process. This 2 The Fischer-Tropsch process is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process, a key component of gas-to-liquids technology, produces a petroleum substitute, typically from coal, natural gas, or biomass, for use as synthetic lubrication oil and as synthetic fuel.
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Transforming Combustion Research Through Cyberinfrastructure could change eventually, but the committee has not yet seen any proposed alternative that could become competitive with liquid-fuel combustion. Even if an economical, nonpolluting, non-greenhouse-gas-emitting energy source were identified and had the potential to replace combustion sources, the overall infrastructure costs of replacing the world’s power plants, cars and trucks, furnaces, home heating systems, and other energy systems would be astronomical. The timescales for transitioning to such a new infrastructure would require generations. Today, some power plants and industrial facilities that are more than 75 years old are still in operation; energy infrastructure does not share the short life cycles of some technologies. In addition, most possible future energy technologies are relatively immature, and many years of R&D will be needed to make any such solution viable. Research and development of all types of alternative energy sources must be encouraged, but at the same time people must be realistic about the time constants for the replacement of the dominant technology worldwide that powers our lives, our industries, our homes, and our societies in general. Nonetheless, it would be dangerous to discount the problems associated with large-scale reliance on today’s combustion technologies. They are certainly the major source of greenhouse gases, and although combustion is a lot cleaner than in the past, pollutant emissions from combustion systems are still very serious problems. However, given the previous discussion, it is likely that the world will burn fossil fuels for another century or even longer. Liquid petroleum fuels may be gone in about a hundred years, but world resources of coal are likely to remain for a longer time, and the costs of production of these fuels will make them attractive in economic terms for many years. If one accepts the projection that combustion will remain a dominant energy and power source for world society for another century, there must be a commitment to making combustion perform much more efficiently, more economically, and in a much more benign way than it does today so as to preserve contemporary ways of life while society waits for new technologies to find replacement energy systems. Without modifications, current rates of emissions of greenhouse gases will likely cause environmental effects, the extent of which may not be known for generations, and other toxic emissions may pollute societies in completely unacceptable ways. The committee believes that this is a crucial point in history and that it is essential to leverage state-of-the-art cybertechnology to develop ways to improve the efficiency of combustion while lessening its detrimental emissions.
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Transforming Combustion Research Through Cyberinfrastructure CYBERINFRASTRUCTURE IN COMBUSTION Ongoing research in combustion science and engineering is steadily advancing our abilities to produce energy that is cleaner, cheaper, and more environmentally benign. However, as in other areas of science, this research is only leading to incremental improvements in technologies. For example, the present understanding of burn efficiencies and by-products is limited by the challenges of modeling such complex events. Innovations in combustion systems are often explored through the slow and expensive process of experimentation, which may still give only a limited understanding about by-products and scalability. If combustion could be adequately modeled, parameters could be more readily varied, and better efficiencies and reductions in undesirable by-products could be sought. Similarly, explorations of new fuel molecules depend heavily on experiment because it is not yet possible to predict how a novel molecule will perform in a combustion system. Researchers are handicapped because there is no easy way to find data collected by others, although having such a capability would eliminate redundant experiments and calculations while enabling faster propagation of improved parameter values, models, algorithms, and so on. An extremely effective way of coordinating available resources in search of a technological solution is through a community-wide cyberinfrastructure. Such an approach collects the contributions of all researchers; channels their research toward major goals; focuses their efforts toward the most productive tasks; facilitates the sharing of tools, data, and computing resources; and reduces the waste of time and effort of conflicting and unproductive activities. In the field of combustion, a few examples of such a community-wide activity from the past can show just how valuable such an approach has been. The CHEMKIN family of simulation tools was developed at the Sandia National Laboratories (Kee et al., 1980), and those tools rapidly became a genuine standard that was used by researchers all over the world. Similarly, the GRIMech chemical kinetic reaction model3 was developed by researchers funded by the Gas Research Institute (GRI), and it too became a standard used throughout the world combustion community. Both projects were eventually terminated owing to inadequate financial support from their sponsors, and while the CHEMKIN simulation tools were taken over by a private company (Reaction Design, 2009), the community kinetic mechanism activity has not been renewed, despite well-intentioned attempts to revive it (Frenklach, 2007). Technology has reached the point at which it is now possible to conceive of a national, 3 See hppt://www.me.berkeley.edu/gri_mech/version30/text30.html. Accessed October 15, 2010.
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Transforming Combustion Research Through Cyberinfrastructure or even international, CI. This report suggests that the conditions for CI can be promoted and that the establishment of a CI for combustion research represents the best possible way for the combustion community to contribute expeditiously to reducing the problems that society faces in producing energy. As is discussed in this report, combustion R&D integrates information from a number of distinct disciplines (chemistry and chemical engineering, mechanical and aerospace engineering, and others) across a broad range of scales, from the atomistic to large-scale engineering systems. At the present time, this data-integration process is slow and tedious, and it only works well when there are cooperative relationships among the researchers working on different aspects of the problem. Progress in combustion R&D could be greatly enhanced by improving how data are integrated both within the individual subdisciplines and, perhaps more importantly, among the disciplines. A cyberinfrastructure would provide the means needed to exchange data across all of the subdisciplines that are required to make progress in combustion: A properly designed CI could not only facilitate the sharing of data within a subdiscipline but also facilitate the transfer of information among different subdisciplines. Marshaling the power of a CI would dramatically speed the flow of information within the combustion community and consequently significantly decrease the time required to develop new combustion systems that can cleanly and efficiently burn existing fuels while assessing the relative merits of different proposed alternative fuels. ORGANIZATION OF THE REPORT This report explains the need for a combustion cyberinfrastructure and the relationships between combustion science and computer science needed to implement such a CI; it also develops a strategic view for the development of the CI. Planning for the CI is beyond the scope of this report; however, the report does recommend steps for the planning process and conditions that need to be met for the eventual CI to be successful. Following this introductory chapter, in Chapter 2 the committee first defines “cyberinfrastructure” and then addresses the architectural and structural decisions that must be made to construct such a research infrastructure. As seen in Chapter 3, research in combustion is characterized by the interaction of experiment and simulation across a wide range of disciplines and a disparate range of length- and timescales. Data produced by complex simulations or detailed experiments have to flow smoothly throughout the community of researchers and engineers and
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Transforming Combustion Research Through Cyberinfrastructure be processed by advanced software tools that utilize a wide spectrum of processing, storage, and communication capabilities. All of this must be deployed, operated, and maintained by experienced personnel as part of a sustained community-wide effort. Other scientific disciplines have constructed cyberinfrastructures that meet their unique needs; Chapter 3 of this report examines those needs for the combustion community. Chapter 4 contains the recommendations that the committee believes should be followed for the successful construction and operation of a combustion cyberinfrastructure. This report contains six appendixes that provide the following: A discussion of the GRIMech model for the combustion of natural gas, A discussion of CHEMKIN Chemical Kinetics Software and its historical background, A description of the computation approach, direct numerical simulation, A discussion of chemical kinetic reaction mechanisms, The committee meeting agendas, and Biographies of the committee members. REFERENCES Frenklach, M. 2007. “Transforming Data into Knowledge—Process Informatics for Combustion Chemistry.” Proceedings of the Combustion Institute, Vol. 31, pp. 125-140. Heinberg, R. 2003. The Party’s Over: Oil, War, and the Fate of Industrial Societies. Gabriola Island, British Columbia, Canada: New Society Publishers. Kee, R.J., J.A. Miller, and T.H. Jefferson. 1980. CHEMKIN: A General-Purpose, Problem-Independent, Transportable, FORTRAN Chemical Kinetics Code Package. Report SAND80-8003. Sandia, Calif.: The SANDIA National Laboratories. Perlak, R.D., L.L. Wright, A.F. Turhollow, R.L. Graham, B.J. Stokes, and D.C. Erbach. 2005. Bioenergy and Bioproducts: The Technical Feasibility of Billion Ton Annual Supply. Oak Ridge, Tenn.: Oak Ridge National Laboratory. Reaction Design. 2009. Chemkin MFC-3.5. San Diego, Calif. Sheehan, J., T. Dunahay, J. Benemann, and P. Roessler. 1998. A Look Back at the U.S. Department of Energy’s Aquatic Species Program—Biodiesel from Algae. Golden, Colo.: National Renewable Energy Laboratory. U.S. EIA (U.S. Energy Information Administration). 2006. “Country Analysis Briefs: China.” August. Available at http://www.eia.doe.gov/emeu/cabs/China/Environment.html. Accessed December 8, 2010. U.S. EIA. 2007a. Independent Statistics and Analysis. Originally published in U.S. EIA, Annual Energy Outlook 2007, February 2007. Washington D.C. U.S. EIA. 2007b. U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 2006 Annual Report. DOE/EIA-0216. November. Washington D.C.