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A team of researchers that included a Georgia Institute of Technology scientist found that ozone pollution production associated with coal-burning power plants is affected by the geographic location and nitrogen oxide (NOx) emission rates – and not necessarily the size – of those plants.
The finding has implications for the U.S. Environmental Protection Agency's (EPA) efforts to control ozone pollution, suggesting the agency can no longer equally value power plant emissions across the nation. It also gives power companies insight into where they should build new power plants and the effect of their size on ozone production.
"We think that our research represents an opportunity to build on current efforts to improve air quality," says lead author Tom Ryerson of the National Oceanic and Atmospheric Administration's (NOAA) Aeronomy Laboratory in Boulder, Colo.
The researchers found that emissions from power plants located near hardwood forests result in more ozone pollution than those operating in agricultural or grassland areas. Trees, particularly oaks, emit volatile organic compounds (VOCs) such as isoprene as a byproduct of photosynthesis. When VOCs released from the Earth's surface are oxidized in the atmosphere in the presence of NOx, ozone is formed. Elevated levels of surface ozone can harm human health and vegetation.
Because coal-burning power plants are largely concentrated in rural areas of the eastern United States – where there are more VOC-producing trees – ozone pollution has been a significant issue for the East, and for the Southeast in particular. Coal-burning plants contribute about 25 percent of the nation's overall NOx pollution, which leads to ozone production. The ozone issue affects rural areas and cities because ozone pollution can travel up to 100 miles downwind. Cities are also fighting ozone associated with vehicle emissions, which account for 53 percent of NOx emissions.
"The Southeast traditionally has had an ozone attainment problem," says Greg Huey, one of the study's authors and an associate professor in the
School of Earth and Atmospheric Sciences at Georgia Tech. "The Southeast is more rural than the Northeast, but you have hardwood forests emitting a lot of VOCs such as isoprene. So you're stuck with high VOC levels. The Southeast is also hot, sunny and humid, and sunlight and water vapor are two of the essential ingredients to initiate photochemistry in the atmosphere. The Southeast is a photochemical pressure cooker, and all you need are NOx emissions to produce ozone."
For the Science study, NOAA and Georgia Tech researchers collected atmospheric data while flying downwind of three coal-burning power plants. Two were Tennessee Valley Authority plants – Cumberland and Johnsonville – located in rural Tennessee where there are a lot of hardwood trees with high VOC emissions. The third was a Thomas Hill, Mo., plant surrounded by farms and grasslands, which have low VOC emissions.
In comparing the two Tennessee plants to the Missouri plant, researchers found that VOC concentration – which is associated with location – is also a key factor in ozone production. The Thomas Hill plant produces 2 ozone molecules per molecule of NOx emitted, and it emits 4 tons of NOx per hour. Meanwhile, the Johnsonville plant makes about 7 ozone molecules per molecule of NOx emitted and emits 2 tons of NOx per hour. So even though the Thomas Hill plant emits twice as much NOx as the Johnsonville facility, it produces only about half the total ozone because of differences in VOC concentration.
Researchers found that the large Cumberland plant emits 14 tons of NOx per hour and makes 2 ozone molecules per molecule of NOx emitted. Consequently, the Cumberland plant only makes about twice as much ozone as the Johnsonville plant, which emits a factor of 7 less NOx per hour than the Cumberland plant. The Johnsonville facility is more efficient in producing ozone, yet the two plants have an identical concentration of VOCs in the surrounding atmosphere. Researchers attribute the difference in ozone production to differences in the NOx concentration around the plants. The high concentrations of NOx associated with the large Cumberland plant promote a series of reactions that don't form ozone, but eliminate the available NOx, Ryerson explains.
"So if you went to the trouble of cutting the Cumberland plant's NOx emissions, you may still get the same amount of ozone in the end because it's just going to get more efficient in producing ozone," Huey explains. In fact, Cumberland has reduced its NOx emissions by half in the past six years, yet its total ozone yield has stayed about the same.
"What we learned in this study is the need to think about how we make power plants cut NOx emissions," Huey says. "Also, it might be better to build one bigger power plant than a lot of smaller ones. Again, you have Cumberland, which is a larger plant than Johnsonville, but it produces ozone much less efficiently."
"The other thing this study shows is that it's probably better to build a power plant in an area where you don't have a lot of VOCs – the other fuel for making ozone," Huey says.
The researchers have communicated the results of their study to EPA in hopes that it will provide a scientific basis for NOx emission reduction policies.
"I believe EPA has gotten this message," Huey says. "In fact, I think they like it because it helps them put a dollar value on NOx emissions. It helps them work out an economic plan.... What we're telling them is don't value the NOx over here like you value the NOx over there."
As for further research, Huey says: "We don't need to prove this point again. We need to improve the database to understand power plant ozone production in various locations and seasons – from late spring to early fall – so we can estimate ozone production efficiency better.... For now we can broadly predict ozone formation rates using empirical models, but it would be valuable to confirm how well these models work in a variety of locations."
– Jane M. Sanders
For more information, contact Greg Huey, School of Earth and Atmospheric Sciences, Georgia Tech, Atlanta, GA 30332-0340 (Telephone: 404-894-5541) (E-mail: greg.huey@eas.gatech.edu); or Tom Ryerson, Aeronomy Laboratory, NOAA, 235 Broadway St., Boulder, CO 80303 (Telephone: 303-497-7531) (E-mail: tryerson@al.noaa.gov)
Paper Partnership
Georgia Tech's new center for paper studies will address industry challenges.
Paper: it pervades every part of our life. Its forms are myriad, from the paper in this magazine to the wallpaper in our homes. Accordingly, the pulp and paper industry plays a large economic role in the United States, accounting for revenues of nearly $170 billion a year.
Georgia Tech and the Institute for Paper Science and Technology (IPST) in Atlanta have joined forces with the paper industry to create a new research center, the Center for Paper Business and Industry Studies (CPBIS). At the Visy Paper Mill in Conyers, Ga., CPBIS executive director Jim McNutt, left, and IPST associate director of business development David Bell, center, discuss the industry with David Kosboth, general manager of Visy.
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Yet, in spite of its significance, the industry has suffered large setbacks in recent years. Profits have weakened, companies have been merged and acquired, and overall, shareholder values have deteriorated.
To address these issues, the Georgia Institute of Technology and the Institute for Paper Science and Technology (IPST) in Atlanta have joined forces with the paper industry to create a new research center, the Center for Paper Business and Industry Studies (CPBIS). The new center is funded largely by the paper industry and a $2 million grant from the New York-based Sloan Foundation. The center will offer value-added service to the paper industry, while providing unique educational opportunities to Georgia Tech and IPST graduate students.
The CPBIS is the 16th of 17 industry centers funded by the Sloan Foundation and is part of a major effort by the organization to create academic communities dedicated to completely understanding particular industries. The foundation requires cooperative industry funding and encourages a direct approach to industry research through regular contact between academics and industry leaders.
Efforts at the CPBIS will concentrate on the business fundamentals affecting the U.S. paper industry within the context of the global industry, while generating focused research and producing experts for the future of this complex and competitive business. Initially, five areas of interest will be addressed: globalization, commercialization, community interactions, workplace transformations and enterprise effectiveness.
The work will be conducted by a diverse group of researchers from IPST and several Georgia Tech academic units, including the Ivan Allen College, DuPree College of Management and the College of Engineering.
"The creation of the center will help us channel the energies and the talents of the Georgia Tech faculty toward the pulp and paper industry," says Tom McDonough, a professor and senior research fellow at IPST, who will serve as the center's director. "We have excellent resources here, and now we have an opportunity to take advantage of them for the good of the industry."
The benefits of this collaboration are clear. Jim McNutt, new executive director of the CPBIS, explains, "The center will become a place where we seek to completely understand the industry, while providing high-quality research with practical outcomes from that research." Officials at the Sloan Foundation believe researchers must be "connected to the industry at the hip," an objective that McNutt says he is determined to meet.
McNutt also points out another benefit to the industry – the creation of a cadre of graduates who are in tune with and trained to address the business management and liberal arts needs of the pulp and paper industry. "The classes to be offered by the center and the hands-on experience from the ongoing research will give graduate students experience they cannot obtain elsewhere," he says. "It is this meshing of the theoretical and practical that makes the educational opportunities afforded by the center so valuable."
While the administrative aspect of setting up the center is nearly complete, the business of running it has only just begun. Plans are under way to offer classes through CPBIS, and funding for seven research projects will begin soon. Additional projects will be added in the future, as well as seminars and an expanded internship program.
David Bell, development director of IPST, speaks enthusiastically about the first major project jointly undertaken by Georgia Tech and the IPST (i.e., the establishment of CPBIS). He notes that IPST has excellent contacts in the industry, while Georgia Tech provides liberal arts and management expertise. "We can use the great strengths of both institutions and apply those to the paper industry," he adds.
– Patricia J. West, freelance writer
The same technology that senses an impending electrical failure in aircraft is being used to detect a human neurological system malfunction – epileptic seizures.
A team of researchers, including one from Georgia Tech, have found that a
series of electrical blips in the brain precedes seizures by as much as
seven hours. This diagram illustrates a technique, on which a patent is
pending, for analysis of brain wave activity to detect and abort seizures
before they occur.
Click here to view larger version
A collaboration between George Vachtsevanos, a professor in the Georgia Institute of Technology School of Electrical and Computer Engineering, and neurologists at the University of Pennsylvania and Emory University has found that a series of electrical blips and burps in the brain precedes seizures by as much as seven hours.
Their study, published in the April 2001 issue of the journal Neuron, offers the hope that onset of seizures can be predicted and possibly halted in patients for whom medicines don't work and surgery is not an option.
Seizures are produced by abnormal electrical discharges in the brain and can cause convulsions and loss of consciousness. Most of the 50 million epilepsy patients worldwide do not know when a seizure will occur and many, especially children, cannot be treated.
Georgia Tech has applied for several patents on a technique Vachtsevanos and his graduate students developed to analyze brain wave activity based upon patient-specific prediction algorithms. A company is interested in licensing the technology to develop a miniature pulse-generating device. When implanted in the brain, it would continuously monitor brain wave activity, and detect and abort a seizure long before it occurs.
Vachtsevanos' technique analyzes huge data sets of real-time information to predict when critical electrical systems, like those found in aircraft, might hiccup and begin to fail. Those systems can then be reset, avoiding interruptions of power.
A decade ago, Vachtsevanos began working with physicians at the Medical College of Georgia to understand the meaning of electrical signals as recorded by electroencephalogram (EEG) devices. Epileptics suffering a seizure will produce a jagged, highly fluctuating brain wave pattern, but so-called "normal" activity in advance of a seizure is hard to interpret, he says.
Four years ago, Vachtsevanos formed a new collaboration with former Emory University neurologist Brian Litt and his colleagues, who were able to provide reams of recordings taken from five patients monitored for weeks at a time by EEG electrodes implanted in their brains. These patients were also videotaped so that any changes in behavior could be matched to their brain waves.
By studying those patients and their brain waves, Litt, now at the University of Pennsylvania, Vachtsevanos and other researchers at Emory uncovered an early warning system. They found that bursts of electrical energy could be detected as much as seven hours before a seizure. And two hours in advance of a seizure, a series of frequent, tiny and symptomless seizures occurred, unbeknownst to patients.
Vachtsevanos is proud that the systems he developed to keep airplanes and helicopters flying smoothly may be able to keep a brain chugging along steadily, too, he says.
"These are very basic fundamental techniques that analyze signals and extract any abnormal deviation," Vachtsevanos explains, adding that there may be additional biological uses of such systems - such as predicting and stopping irregular cardiac rhythms before they produce a heart attack.
Similar diagnostic and prognostic technologies developed by
Vachtsevanos' group are improving industrial product quality and process productivity by increasing uptime and conducting maintenance only when needed.
– Renee Twombly, freelance writer
Intriguing seafloor ecosystems in the Gulf of Mexico have prompted a unique, multidisciplinary study that may advance the understanding of marine microbiology and the adaptations of microorganisms to extreme environments that may exist elsewhere on Earth and on other planetary bodies.
Georgia Tech scientist Patricia Sobecky prepares for a dive to the ocean floor in the Gulf of Mexico aboard the Johnson Sea Link, a four-person submersible vehicle from the Harbor Branch Oceanographic Institute in Fort Pierce, Fla.
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Researchers from the Georgia Institute of Technology, the University of Georgia and Texas A&M University have begun a year's worth of data and sample analysis following a two-week underwater expedition in the Gulf in July. They are studying the biological communities associated with seafloor ecosystems called brine pools and hydrocarbon seeps.
The Gulf of Mexico seafloor contains vast pools of liquid and gaseous hydrocarbons. Two unique features, brine pools, extremely salty areas on the ocean floor, and hydrocarbon seeps, where oil and gas leak from the ocean floor, occur in the Gulf. Here, methane combines with water and hydrocarbons to form ice-like clathrates called gas hydrates that can breach the ocean floor.
"This environment creates diverse and extreme niches promoting the growth of thriving communities of macro- and microorganisms living in the sediments of oil seeps, in brine pools and hydrates," says Patricia Sobecky, an assistant professor in the Georgia Tech School of Biology.
A 22-person research team explored and sampled the ecosystems in July using a four-person submersible vehicle, the Johnson Sea Link operated by the Harbor Branch Oceanographic Institute (HBOI) in Fort Pierce, Fla. The crew launched the Sea Link from the HBOI's research ship, the Seward Johnson. The research team was led by Sobecky, Georgia Tech Associate Professor of Biology Joe Montoya, Mandy Joye of the University of Georgia and Ian McDonald of Texas
A&M. Each researcher, including undergraduate students, graduate students and technicians, took part in at least one dive to the sea floor.
Researchers reported being awed by the brine pool and hydrocarbon seeps they studied. Little is known about these ecosystems because of the time and expense associated with researching them. In addition to the Gulf of Mexico locations, these ecosystems also exist along the coast of Mexico and in the North Sea.
Montoya and Sobecky described thick bacterial mats that can cover extensive parts of the ocean floor in these ecosystems. Some of the mats were as large as 50 square meters. Researchers sampled these mats at depths of 500 to 600 meters while working from the submersible vehicle.
"Although analysis of samples from this cruise will take at least a year, preliminary results, including some data obtained while we were still at sea, demonstrate the profound impact of the hydrocarbon seeps on the bottom communities in the area," Montoya says. "In addition to the extensive bacterial mats, large aggregations of mussels and tube-worms and hosts of smaller, free-living invertebrates were near the seeps and around the brine pool. The influence of the hydrocarbon seeps may also extend upward into the water column, where plumes of gas bubbles and oil droplets may nearly reach the surface."
Each lab in this collaborative project brings a unique area of expertise to the study. For example, Sobecky's lab hopes to find biotechnology applications derived from the biological samples collected from the sea floor.
"We do a lot of searching for novel genes and novel mechanisms of adaptation," she says. "There may be accessory genetic elements in bacteria that allow them to adapt.... So you never know what you might find."
Meanwhile, Montoya's lab is investigating the movement of nitrogen and carbon in the sediments and invertebrate communities, as well as in the overlying water column.
Applications of the researchers' findings also could be found in energy and planetary exploration, they say. Some scientists have suggested the hydrocarbon methane, derived from methane hydrates on the ocean floor, as a potentially important fuel source.
It may also be possible to extrapolate information on this ecosystem to learn more about the environments of places like the Jovian moon Europa. A large body of evidence indicates the existence of an ocean there; it may harbor environments similar to those around methane hydrate deposits on Earth, Montoya says.
This research is being funded by the National Science Foundation's Life in Extreme Environments Research Program and the National Oceanic and Atmospheric Administration's National Undersea Research Program.
To read reports posted while the researchers were at sea this past July, see the Harbor Branch Oceanographic Institute's Web site at www.at-sea.org. Follow the link to the mission titled "Diving to Extremes: Life in Hydrocarbon-Based Ecosystems."
– Jane M. Sanders
photo by T. Michael Keza
For more information, contact David Bell, IPST, 500 10th St. NW, Atlanta, GA 30318-5794. (Telephone: 404-894-9592) (E-mail: david.bell@ipst.edu)
Predicting and Halting Epileptic Seizures
Researchers find electrical pattern that precedes seizures.
courtesy of George Vachtsevanos
For more information, contact George Vachtsevanos, School of Electrical and Computer Engineering, Georgia Tech, Atlanta, GA 30332-0250. (Telephone: 404-894-6252)
(E-mail: george.vachtsevanos@ee.gatech.edu)
Mystery Under the Sea
Researchers study hydrocarbon-based biological communities in unique ocean floor ecosystems.
photo by Heath Mills
For more information, contact Patricia Sobecky, School of Biology, Georgia Tech, Atlanta, GA 30332-0230. (Telephone: 404-894-5819) (E-mail: patricia.sobecky@biology.gatech.edu); or Joe Montoya, same address. (Telephone: 404-385-0479) (E-mail: joseph.montoya@biology.gatech.edu)
Also see Research Links news stories.
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Last updated: Nov. 12, 2001
