Environmental t News The CO2 sponge
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moved to not only a design but a fully delineated technology,” he adds. His process works by forcing air through a chamber filled with packing material that provides plenty of surface area for air to come into contact with sodium hydroxide solution, a highly alkaFr ank Zeman
apturing heat-trapping CO2 and storing it underground may help slow global warming. But plans so far have focused on scrubbing CO2 from power plant stacks, which account for only half of all emissions. Now, a few scientists hope to catch at least
A scaled-up version of this device may one day suck CO2 directly from the air. The prototype wind tunnel directs air through a bed of packing material, where fluid absorbs the greenhouse gas.
some of the other half—which puffs out of tailpipes, homes, and other nonpoint sources—directly from the air. New research published in ES&T (pp 7558–7563) suggests that it may be feasible to suck CO2 out of the atmosphere using relatively straightforward technology, similar to that currently used by pulp and paper mills. Frank Zeman, an engineer at Columbia University, reports that industrial-scale scrubbers could pull CO2 from ambient air, and the gas then could be stored in the same ways proposed for CO2 from power plants (e.g., by pumping it deep underground or into the ocean). According to Zeman’s calculations, the process would store more carbon than it burns, addressing a key challenge faced by air capture technology. “Air capture of CO2 has come a long way in 5 years,” Zeman says. Once purely theoretical, “it’s
line liquid that absorbs CO2. The carbon-containing solution is then combined with lime to precipitate a powdery limestone. The limestone is heated in a kiln to release a pure stream of CO2, ready for storage. The price tag: as much as $200 per metric ton of carbon captured, Zeman estimates. According to his collaborator, David Keith of the University of Calgary (Canada), the steep price could come down with technical improvements. The captured CO2 could also be used to make products such as transportation fuel, he adds. And the basic technology for air capture is used in “every pulp and paper mill in the world,” he says. “If you wanted to, you could build a full-scale air capture system today and it would work.” “Nature does this every day, all the time,” says earth scientist Greg Rau of Lawrence Livermore National Laboratory. “The ocean has
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consumed 30% of all industrial CO2 emissions ever made.” Rau is developing his own methods for capturing CO2 from the air and from power plants. For now, only a few groups are working seriously on air capture, but the numbers may grow. Billionaire Richard Branson recently announced the Virgin Earth Challenge, a $25 million prize for a practical design to reduce greenhouse gas levels. Zeman says he has no plans to enter the competition. Zeman’s former mentor, Klaus Lackner of Columbia University, has a technology that is possibly the closest to going commercial. Lackner did much of the early design work on air capture and now has a private company, Global Research Technologies, that has developed a prototype system. The ultimate plan involves carbonsucking towers nearly 100 meters tall placed in remote locations where they won’t be eyesores. Air capture of CO2 is difficult at best, Zeman acknowledges. Ambient air contains only 380 parts per million of CO2, so removing just half of it means moving a lot of air. A scrubber has to process about 250 times more ambient air than flue gas to capture the same amount of carbon. Detractors point to this problem as well as other practical limitations. “This is a patch solution in the sense that you would still have mercury from burning coal” and other issues related to mining and using fossil fuels, Zeman says. “Does [air capture] condone the wasteful, SUV lifestyle? I don’t know,” Zeman admits. “The best solution is always to not make the problem in the first place.” But cleaning up the mess that’s been made requires a variety of tools, possibly including air capture, he contends. —ERIKA ENGELHAUPT © 2007 American Chemical Society
COURTESY OF FEUERWEHR WESEL
After the phaseout of firefighting foams that contain perfluorooctane sulfonate (PFOS), manufacturers switched to fluorotelomer foams. But these replacements may also have adverse environmental impacts. In September, a group of speakers at a U.K. Insti-
Firefighting foams are readily dispersed into the environment.
tution of Fire Engineers conference urged firefighters to consider swapping their blaze-battling chemicals once again for a newer generation of fluorine-free firefighting foams (FfreeF). Aqueous firefighting foams are a firefighter’s number one weapon against hot and dangerous chemical or hydrocarbon fires, because they seal off and choke the blazes. In the past, foams that contain, or break down to, PFOS—a persistent, bioaccumulative, and toxic compound—have contaminated groundwater. On the island of Jersey, located off the coast of England, for example, the cost of cleaning up the underground drinking-water source contaminated by firefighting exercises is estimated to be millions of pounds. In the U.S., groundwater on and around military bases has been contaminated by PFOS and other perfluorosulfonates because of firefighting chemicals (Environ. Sci. Technol. 2000, 34, 3864–3870). Now that foams containing fluorotelomer compounds have
replaced PFOS foams, scientists warn that not enough is known about these replacements. “Fluorotelomer environmental degradation products are extremely persistent, surviving in groundwater for at least a decade, and are, as yet, of unknown bioaccumulative capacity and toxicity,” chemist Roger Klein from the University of Bonn (Germany) told participants at the U.K. meeting. “There is no safe level for discharge of a substance which will accumulate indefinitely and which is of unknown biological activity.” According to Klein, chemical principles indicate that fluorotelomer foams should ultimately degrade to perfluorohexanoic acid (PFHxA) by a partial dehydrofluorination process. Although this breakdown pathway has not been directly demonstrated experimentally, other chemists agree that this is a likely chain of events. Degradation to PFHxA is one of two possibilities considered by fire-control consultants Joseph Scheffey and Christopher Hanauska in a 2002 market analysis. “The telomer-based surfactants do biodegrade down to a molecule that contains the highly fluorinated carbon chain, and this molecule is not expected to further biodegrade. But what molecule this is has not been established and is currently a subject of contention. Two possibilities apparently exist: the molecules biodegrade down to perfluorohexanoic acid, or the biodegradation product is unknown,” Scheffey and Hanauska wrote. They also speculated that PFHxA could attract regulatory interest in the future because of its similarity to perfluorooctanoic acid, which is being investigated by the U.S. EPA. Environmental monitoring, conducted as part of the European
News Briefs Vehicles’ carbon emissions dip
The rate of CO2 emissions from new U.S. cars and light trucks has dropped for the first time in 20 years, but total emissions have continued to rise since 1990, according to a new report from the advocacy group Environmental Defense. The authors analyzed CO2 emissions data from the U.S. Energy Information Administration through 2005, the most recent data that are available. Overall, automobile emissions have risen 73% since 1973. A pattern of increased driving since that time contributed to the increase, as did a drop in average fuel economy since 1988, the authors note. From 2004 to 2005, the average emission rates of new vehicles dropped 3%, a change that the authors attribute in part to tighter fuel economy standards for light trucks.
Similar challenges for China, U.S.
As China rapidly develops its economy, its increasing air pollution leads to more human-health effects. The problems are reminiscent of those faced by the U.S. during the past 30 years. In a new report, researchers in the U.S. and China use case studies in Los Angeles and Dalian to examine transportation, pollutant controls, U.S. fuel standards, and China’s coal-burning practices, among other issues. The report Energy Futures and Urban Air Pollution: Challenges for China and the United States, published in September by the U.S. National Research Council, suggests more federal oversight for both countries as well as empowering China’s State Environmental Protection Administration.
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The fate of fluorotelomer firefighting foams
Environmentalt News Perforce project on perfluorinated chemicals, revealed relatively high levels of PFHxA in European rivers and coastal waters. This finding was confirmed in data presented by Josef Müller and Mark Bücking of the Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg (Germany). “At the moment, we can only speculate about the sources,” says chemist John Parsons at the University of Amsterdam. A second phase of Perforce will be tackling this issue, among others, he says. But Tom Cortina, executive director of the international Fire Fighting Foam Coalition, an industry association of fluorotelomer foam manufacturers, says that fluorotelomer replacements are used
in relatively small amounts. Only about 5% of the fluorotelomer-based products manufactured worldwide are used in the production of firefighting foams, Cortina added. Much of the rest is used in stainproofing and paper coatings. Global volumes may be small, says Klein. “But firefighting is one of the most dispersive uses imaginable. You don’t take a fabric protector and spray it directly on the environment, but that’s what you do with foam.” A number of European companies have developed FfreeF that meet international performance standards developed by groups such as the International Civil Aviation Organization and the pe-
troleum industry, according to Bogdan Dlugogorski, director of the Research Center for Energy at the University of Newcastle (Australia). “FfreeF provide good replacements for fluorine-based formulations in most applications where foams are employed for fire mitigation,” says Dlugogorski, who presented testing results at the U.K. meeting. “In qualitative terms, telomer and fluoropolymer formulations can achieve truly excellent performance (if formulated well), in comparison to very good performance of FfreeF. In my view, this small difference in performance is more than offset by the environmental advantages of employing FfreeF,” says Dlugogorski. —REBECCA RENNER
Wind doesn’t blow around the clock. Because of its ephemeral nature, making wind a viable alternative energy source requires storage capacity and the ability to release that energy when demand—and market price—is high. New technology from one company and a project in Iowa may show how to bring these two requirements together. Compressing air for energy isn’t a new idea, but its use for wind energy is. When energy demand is low, energy from wind turbines can force air into an underground aquifer. When demand is high, a utility can expand the pressurized air and transform it back into electricity by pumping it to the surface and running it through a turbine. Two compressed-air energy-storage (CAES) installations exist—one in Huntorf, Germany, and the other in McIntosh, Ala.—but neither relies on wind energy for compression or expansion. The Iowa Association of Municipal Utilities (IAMU), which represents more than 550 electricity, water, gas, and telecommunications utilities in Iowa, is pioneer-
Gener al Compression
Wind energy on demand
General Compression's wind turbine system.
ing a unique wind-storage method to generate electricity and plans to have it up and running by 2011. Officials envision underground storage, in this case in a natural aquifer, as a way to take advantage of variations in the price of electricity. “When you combine wind energy with compressed-air energy storage, you make wind energy dispatchable”—in other words, available on demand, says Kent Holst, development director for the Iowa project. The project, created by IAMU, is dubbed the Iowa Stored Energy Park. The $200 million undertaking aims to harness about 75 megawatts (MW) of power from
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wind turbines across Iowa, supplemented with electricity bought at off-peak times delivered by existing power lines. The energy would power motors to compress air and force it 2000 feet below ground into a natural aquifer near Dallas Center, in central Iowa. The Iowa plant should produce 268 MW when running at full capacity, which is enough to power about 75,000 homes. Most of the energy will be used by the municipal utilities in Iowa and in surrounding states that invest in the park. The rest will be sold on the grid. Although Iowa is a prime location for wind and natural aquifers, finding a site still posed a challenge for the project team. The Dallas Center aquifer was chosen because it has all the necessary geological features, including size, depth, and structure—and isn’t currently used for storage. One company hopes to commercialize the wind-energy storage method. General Compression of Attleboro, Mass., says it can bring CAES into widespread use. The company, created in March 2006, has $5 million of seed funding to establish underground storage of compressed air that can later be
also pump compressed air into a nearby salt dome, aquifer, limestone cavern, or depleted gas field, Marcus says. To retrieve that power, the compressor is configured as an expander, which turns the change in pressure as air is released into rotary motion. The expanders are connected to electrical generators. More than 10,000 MW of electricity is generated from wind in the U.S.; with proper development, wind could supply 20% of the nation’s energy needs, according to the Department of Energy’s National Renewable Energy Laboratory. By providing the capability to sell that energy for the highest price possible, CAES makes wind all the more desirable. —JEAN THILMANY
The posters that hang on the walls of the soil chemistry group at ETH Zurich hint at the breadth of interests of the researchers there—the data on plants that take up and fractionate iron isotopes, speciation of heavy metals in soils, fate of arsenic in irrigation waters in Bangladesh, and more. The leader of this diverse group, Ruben Kretzschmar, brings his wideranging interests to ES&T as one of its new associate editors. Stephan Kraemer, who worked under Kretzschmar during his first years at ETH Zurich, says that Kretzschmar has “a wonderful intuition” for new methods and a willingness to apply them. “This creative open-mindedness, his fairness and generosity towards colleagues, collaborators, and students, as well as his almost encyclopedic knowledge of soils and environmental chemistry,” make him well qualified to serve as an editor of ES&T, Kraemer says. Kretzschmar became an associate editor of ES&T on September 1, 2007. He will help edit research articles for a special focus group of
S. Lindig/ UWIS
Soils and much more
News Briefs Western governors’ GHG pact
The governors of six western states and the leaders of two Canadian provinces announced in August that they will enforce a regional cap on greenhouse gas (GHG) emissions. Known as the Western Climate Initiative, the pact is aimed at reducing emissions of CO2 , methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Participants can develop their own plans to meet the goal of reducing regional emissions to 15% below 2005 levels by 2020. The reductions should be “economy-wide”, the pact notes, and should affect stationary, residential, and transportation sources; energy supply; and commercial, industrial, waste management, and agricultural facilities. The governors of California, Arizona, New Mexico, Oregon, and Washington unveiled the initiative in February and are now joined by leaders in Utah, British Columbia, and Manitoba.
GHG control costs
Ruben Kretzschmar of ETH Zurich.
papers in ES&T on the use of stable isotopes to measure microbial reactions in the environment, which will be published next spring. Kretzschmar says he started out being interested in environmental problems and food production in developing countries. But in 1983 in Germany, environmental programs were scarce. Geology, agriculture, and forestry were the main paths to such research. “Today, a lot of environmental problems are rooted in land use,” Kretzschmar says, which feeds into his curiosity about the interface between soil science, the environment, and how humans use natural resources for primary production (such as agriculture and forestry).
Returning greenhouse gas (GHG) emissions to 2004 levels by 2030 could cost the equivalent of 0.3– 0.5% of projected global gross domestic product in 2030, according to a new report by the UN Framework Convention on Climate Change (UNFCCC). The report analyzes the worldwide financial commitment needed to address climate change. The UNFCCC projected investment needs at $148 billion per year for energy generation, including renewable energy, nuclear power, hydropower, and carbon capture systems; $36 billion for energy efficiency measures; and $35–45 billion for R&D. The group suggests partly redirecting investment flows through an international carbon market, noting that the UN’s clean development mechanism already generates $25 billion annually.
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harvested as electricity when the price is right. General Compression plans to offer its dispatchable wind turbine system for sale to turbine operators within the next 3 years. The system features a compressed-air wind turbine, a pipeline network that collects and stores compressed air, and a mini power plant of expanders and generators, says Michael Marcus, the company’s president. The blowing wind lifts the turbine blades, spinning the compressor. In turn, the compressor pressurizes air and pumps it down the tower into an underground network of pressurized pipes. The pipes collect and store 6–12 hours of wind-generated energy. For longer storage, the technology can
Environmentalt News Kretzschmar embarked on his undergraduate work at the GeorgAugust University of Göttingen (Germany) as an agricultural sciences major. He eventually specialized in soil sciences and plant nutrition and studied at the University of Hohenheim (Germany) with Horst Marschner, the wellknown plant mineral nutritionist. Kretzschmar examined rhizosphere chemistry and aluminum toxicity to plants in the acidic soils of Niger for his master’s research, focusing on soil fertility problems. He followed that interest to North Carolina State University, where his work with Wayne Robarge, a
soil chemist, and Sterling Weed, a soil mineralogist, earned him a Ph.D. In 1993, Kretzschmar accepted a 6-year research associate position at ETH Zurich, where he was elected a tenured professor in 1999. Kretzschmar’s group is now as diverse as his background—it includes 15 doctoral and postdoctoral researchers studying various aspects of the biogeochemistry of trace elements in soils and sediments. For the past decade or longer, Kretzschmar says, the disciplines within the soil sciences have overlapped, bringing together physics, chemistry, mineralogy, and biology.
Those who have worked with Kretzschmar admire his scientific knowledge as well as his leadership skills. “Ruben has a very direct style” and is “an effective group leader,” both scientifically and interpersonally, says Jon Chorover of the University of Arizona, who just spent a 6-month sabbatical conducting research alongside Kretzschmar at ETH Zurich. Kraemer, who is now chair of geochemistry at the University of Vienna, says of Kretzschmar: “He is quick to recognize and to tackle emerging research fields within soil and environmental chemistry.” —NAOMI LUBICK
Jennifer Field is typically focused and confident as she rides the trails behind her office at Oregon State University (OSU) on her mountain bike during her lunch break. This is also the way she pursues research, sort of. Friends note that Field is brazenly competitive on the trail, but despite several scientific achievements, she isn’t one to brag. “Jennifer’s just not the type of person who wants to toot her own horn,” says longtime friend and ES&T editorial advisory board member David Sedlak, a professor of civil and environmental engineering at the University of California Berkeley. Field was named an ES&T associate editor on September 1, 2007. Her expertise is firmly rooted in environmental chemistry, and she has experience in engineering and hydrology. Field has seen much success in developing methods for the quantitative analysis of organic compounds in sediment, soil, and sewage sludge. Her work on developing new methods for detecting perfluorinated surfactants and nonylphenol polyethoxy carboxylates, and most recently fullerene nanoparticles, has truly opened the door for other scientists. Typically self-effacing, Field notes that
Courtesy of Jennifer Field
Finding a niche in chemistry and engineering
Jennifer Field, of OSU, and her daughter Laurel, hiking in Switzerland.
she “looks for niches in science, especially in the places where engineering, geology, and chemistry intersect.” Edward Furlong, a research chemist at the U.S. Geological Survey’s National Water Quality Laboratory in Denver, Colo., met Field when she was toiling on her Ph.D. in geochemistry at the Colorado School of Mines. Field has always pursued leading-edge questions in science, Furlong says. Field spent 2 years “turning her lab upside down” trying to remove all of the polytetrafluoroethylene (Teflon) from instruments and con-
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tainers, so she could get clean samples for her work on perfluorinated compounds, Sedlak says. “Now, more people can measure perfluorinated surfactants because Jennifer showed them how,” he says. She began investigating surfactants as a research fellow at what was then known as the Swiss Federal Institute for Water Resources and Water Pollution Control (Eawag) where she worked with ES&T associate editor Walter Giger. Caleb Banta-Green, a University of Washington scientist who studies drug abuse, has worked with Field for only 1 year along with several OSU scientists. The team just released their findings measuring the quantity of illicit drugs in urban sewage sludge. “She is a great teacher,” he says. Field was a guest editor for the December 1, 2006, ES&T Special Issue on Emerging Contaminants, and she will handle the papers in an upcoming tribute to Giger, who will be retiring from ES&T in January 2008. Field adds that riding the trails on her mountain bike is part of what she does to create harmony in her life. “I really value balance in my life, and this is something I want my students to know, too,” Field says. “This is where my 11year-old daughter and husband come in.” —CATHERINE M. COONEY
