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Clarions for Sustainability

Chemical engineers call for action and offer ways to meet future energy and natural resource needs

by Stephen K. Ritter
December 18, 2006 | A version of this story appeared in Volume 84, Issue 51

Nearly everywhere these days the word "sustainability" is popping up. The recent skyrocketing of crude oil prices and the growing concern over how natural resources can be efficiently used and peacefully shared around the world has upped the use of the word

The annual meeting of the American Institute of Chemical Engineers (AIChE), held last month in San Francisco, was no exception. Several technical symposia examined the role of chemical engineers in the pursuit of global sustainability. During the plenary session of the primary symposium on sustainability, the four speakers didn't mince words in delivering this message: The time is at hand to take corrective action to ensure future global prosperity, particularly as developing countries aim to catch up to the standards of living in Europe and North America.

"The status quo is not sustainable-politically, economically, or environmentally," commented Dale L. Keairns, a technical fellow in the Pittsburgh office of Science Applications International Corp. Keairns, who is AIChE's 2007 president-elect, discussed future world energy needs and put the numbers in perspective with current capacities. He explained that overconsumption is a top concern for sustainability, and he presented indicators for measuring sustainability.

For example, in 1950, the average-sized home in the U.S. was about 1,000 sq ft, he said. Today, the average-sized home is 2,500 sq ft. Such largesse is striking when nearly half the world's population, some 2.7 billion people, live on less than $4.00 per day and don't have access to electricity or sufficiently clean water, Keairns pointed out. As more of these people rise out of poverty, the demand on natural resources will increase substantially, he said.

"Sustainability is an international challenge, but it's a solvable problem," Keairns added. "There is a need for technology creativity and social creativity, and chemical engineers will be an integral part of finding the solutions. We bring an important voice as technical choices are considered."

Reuel Shinnar of the Clean Fuels Institute at the City College of New York presented a plan he devised with colleague Francesco Citro for "decarbonization" of the U.S. fuel and electric power infrastructure (Science 2006, 313, 1243). Shinnar advocates the gradual replacement of most fossil fuels with currently available and affordable electricity generated by alternative technologies, such as solar, wind, and nuclear power. His plan places an emphasis on storable solar power that can be used to compensate for variations in energy supply and demand.

Shinnar's research indicates that electricity produced from alternative technologies can directly replace 72% of fossil fuel consumption. This means all residential uses of oil and gas, as well as 80% of gasoline consumption, could be replaced by renewable electricity.

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. "CO2 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 CO2 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 CO2 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 reducing 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 alternative energy sources will depend on economic 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 the average fuel efficiency of cars was 12 mpg. Following government intervention to set fuel economy standards, the efficiency improved to about 21 mpg in 1985. But there hasn't been any improvement since.

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 expects 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 improve 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 environmental 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 president. But understanding what sustainability means is difficult, especially in the context of long-term raw material availability, energy intensity, global warming, and the desire for economic growth.

One of the intriguing statistics he provided 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 countries will be much greater than in the U.S., he emphasized. Even with the anticipated leveling off of world population at something less than 10 billion people, "will this growth scenario be sustainable?" he asked.

Siirola outlined reserve estimates for fossil fuels and other possible raw materials 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 the end, the significant sustainability challenge may not be the availability of feedstocks but the "disposition of the ever-increasing amount of CO2," Siirola added.

With the conclusion of the session, the audience filed out of the lecture hall with the notion that sustainability and alternative energy will be major themes for the next generation of chemical engineers.


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