SCIENCE & TECHNOLOGY
CLARIONS FOR SUSTAINABILITY Chemical engineers CALL FOR ACTION and offer ways to meet future energy and natural resource needs STEPHEN K. RITTER, C&EN WASHINGTON
NEARLY EVERYWHERE these days the lenge, but it's a solvable problem," Keairns word "sustainability" is popping up. The added. "There is a need for technology crerecent skyrocketing of crude oil prices and ativity and social creativity, and chemical the growing concern over how natural reengineers will be an integral part of finding sources can be efficiently used and peacethe solutions. We bring an important voice fully shared around the world has upped as technical choices are considered." the use of the word. Reuel Shinnar of the Clean Fuels InThe annual meeting of the American stitute at the City College of New York Institute of Chemical Engineers (AIChE), presented a plan he devised with colleague held last month in San Francisco, was no Francesco Citro for "decarbonization" exception. Several technical symposia exof the U.S. fuel and electric power infraamined the role of chemical engineers in structure (Science 2006,313,1243). Shinnar the pursuit of global sustainability. During advocates the gradual replacement of most the plenary session of the primary symfossil fuels with currently available and posium on sustainability, the four speakaffordable electricity generated by alternaers didn't mince words in delivering this tive technologies, such as solar, wind, and message: The time is at hand to take corrective action to ensure future POWERED UP global prosperity, particularly as deFinite fossil fuels currently supply dominant share veloping countries aim to catch up to of all U.S. energy use the standards of living in Europe and North America. Petroleum "The status quo is not sustainproducts able—politically, economically, or Coal environmentally," commented Dale Natural gas L. Keairns, a technical fellow in the Pittsburgh office of Science ApplicaNuclear power tions International Corp. Keairns, Hydroelectric power who is AIChE's 2007 president-elect, Biomass discussed future world energy needs Geothermal, and put the numbers in perspecwind, and solar _ tive with current capacities. He 0 10 20 30 40 explained that overconsumption is Quadrillion Btu a top concern for sustainability, and NOTE: Combined transportation fuel and electricity data for 2005. he presented indicators for measurSOURCE: Energy Information Administration ing sustainability. For example, in 1950, the averagesized home in the U.S. was about 1,000 sq nuclear power. His plan places an emphasis on storable solar power that can be used to ft, he said. Today, the average-sized home compensate for variations in energy supply is 2,500 sqft. Such largesse is striking when and demand. nearly half the world's population, some Shinnar's research indicates that elec2.7 billion people, live on less than $4.00 tricity produced from alternative technolo-- I per day and don't have access to electricity gies can directly replace 72% of fossil fuel or sufficiently clean water, Keairns pointed consumption. This means all residential out. As more of these people rise out of povuses of oil and gas, as well as 80% of gasoerty, the demand on natural resources will line consumption, could be replaced by increase substantially, he said. ! renewable electricity. "Sustainability is an international chalWWW.CEN-0NLINE.ORG
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An additional 26% of fossil fuel use can be directly replaced by hydrocarbons, such as methanol produced from synthesis gas, a mixture of hydrogen and carbon monoxide. Syngas can be derived from biomass and from hydrogen generated by electrolysis of water powered by alternative energy sources, he noted. "We can't grow all the biomass we would need, but adding hydrogen produced from alternative energy can increase the capacity to make it feasible," he said. THIS PLAN, once implemented, would also reduce 97% of current total carbon dioxide emissions, he estimated. "C0 2 emissions from fossil fuels are the most likely cause of global warming," Shinnar said. "It's sensible to reduce fossil fuel use." He added that C0 2 sequestration to reduce the global-warming effect of fossil fuels doesn't contribute to sustainability and that replacing fossil fuels with alternative energy is significantly cheaper than C0 2 sequestration. Shinnar believes 70% of his proposed reduction in fossil fuel use could be achieved within 30 years, and up to 90% could be achieved over about 50 years. This time frame would coincide with the expected peak supply of fossil fuels, help secure U.S. "energy independence," and help curb global warming, he said. The cost of implementing his plan would be about $200 billion per year for 30 years, Shinnar added. But this cost would be covered by the amount that would have been spent on importing gas and oil. "There would be little or no overall cost increase," he said. A successful U.S. program could set an example, he said, but there is one lingering question: "Is it politically feasible?" Economist James L. Sweeney of the department of management science and engineering at Stanford University continued the discussion by providing an overview of the financial issues associated with energy efficiency improvements. In effect, he responded to Shinnar's rhetorical question affirmatively by proposing the promotion of a national policy to improve energy efficiency. "We now face real oil prices, and other energy prices, that are sharply higher than we have seen since 1982," Sweeney noted. "The futures market suggests that while there is great uncertainty about whether these prices will increase or drop from current levels, it is most likely they will remain high." Critical to providing a solution is reduc-
ing demand, he said. Sweeney noted that U.S. energy consumption is more than 20% of the world total and that 86% of that amount is derived from fossil fuels. As fossil fuel supplies dwindle, demand for alterna tive energy sources will depend on econom ic forces and policy decisions, he said. Sweeney said an important tool would be a national policy to continue to improve energy efficiency. For example, in 1973 t n e average fuel efficiency of cars was 12 mpg. Following government intervention to set fuel economy standards, the efficiency im proved to about 21 mpg in 1985. But there hasn't been any improvement since.
fossil fuels and other possible raw materi als for the chemical and energy industries. As natural gas and crude oil (the currently favored low-oxidation-state fossil fuel sources) become depleted, biomass and coal (higher oxidation state alternatives) will be exploited. But these latter materials will require much more energy to process into most products, he pointed out.
IN ANOTHER EXAMPLE, he said light emitting diodes (LEDs) should eventually replace incandescent light bulbs, and for emphasis he held up some working LED flashlights. LEDs produce more lumens per watt of electricity than incandescent bulbs, Sweeney noted. They aren't yet as efficient as compact fluorescent bulbs, he added, but the technology is improving and he ex pects the efficiency of LEDs to eventually surpass that of fluorescent lighting. "The least polluting energy is the energy we don't use," he said. The technology to im prove energy efficiency will fall into place, he believes, but it won't happen as quickly as is ideal without government action. "There is clearly much interest in envi ronmental protection, greener chemistry, and the general notion of sustainability within the chemical processing and energy industries," commented Jeffrey J. Siirola, a chemical engineer at Eastman Chemical, Kingsport, Tenn., and a past AIChE presi dent. But understanding what sustainabil ity means is difficult, especially in the con text of long-term raw material availability, energy intensity, global warming, and the desire for economic growth. One of the intriguing statistics he provid ed was an estimate of per capita growth in gross domestic product. He noted that U.S. GDP per capita in 2000 was $30,600, while in Asia it was $3,600 and in Africa it was $2,000. The GDP per capita is expected to rise to about $50,000 in the U.S. and to an average of $33,000 worldwide by 2050, in constant dollars. The rate of increase of economic growth in the developing coun tries will be much greater than in the U.S., he emphasized. Even with the anticipated leveling off of world population at some thing less than 10 billion people, "will this growth scenario be sustainable?" he asked. Siirola outlined reserve estimates for
In the end, the significant sustainability challenge may not be the availability of feedstocks but the "disposition of the everincreasing amount of C0 2 ," Siirola added. With the conclusion of the session, the audience filed out of the lecture hall with the notion that sustainability and alterna tive energy will be major themes for the next generation of chemical engineers. •
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