Volume 12, Number 1, 2003
Oil spills at sea can cause severe and widely publicized environmental problems, but Jim Corbett knows there's another type of pollution associated with shipping as well.
"Although the environmental impacts of collisions and oil spills in the marine transportation industry have received widespread attention, the impacts of air pollution have been largely ignored or underestimated," says Corbett, assistant professor of marine policy in the College of Marine Studies. "Not only were ship emissions thought to be an insignificant contributor to air pollution, they also were considered to be mostly a local concern that was limited to the world's largest port cities."
However, in recent years, Corbett and others have shown that even though most large ships operate under the power of fuel-efficient diesel engines, the high temperatures and pressures in those engines produce significant pollution. In addition, ship engines typically use low-quality oil, called bunker or residual fuel. This fuel, which is the cheapest to use, also is the dirtiest and least environmentally friendly. Corbett says it's "left over" from the refining of crude oil and therefore contains greater concentrations of pollutants than such high-quality fuels as gasoline, kerosene or diesel.
The burning of bunker fuel emits sulfur, nitrogen and other particulates into the air. These emissions have been cited as a principal component in the formation of smog in port cities, as well as contributing to acid rain and adversely affecting human health.
Emissions from cars and trucks have long been regulated, but ships have been left unregulated until very recently, Corbett says, adding that emerging standards for ships still are rather weak, while on-road emissions controls have become even stricter. Although bunker fuel can contain up to 40,000 parts per million (ppm) of sulfur, the diesel fuel used by trucks is allowed only 500 ppm, and new regulations soon will reduce that amount to 15 ppm.
"Concerns about ship emissions are likely to increase as commercial shipping grows in response to global trade," Corbett says. According to some experts, global cargo shipping is expected to triple in the next two decades as demand for consumer goods continues to increase worldwide. Currently, ships import an estimated 67 percent of consumer goods purchased by Americans.
Corbett's work on ship emissions has involved not only assessing their impact, but also identifying ways to reduce them--a task that he says will involve everyone. "Generally, engine emissions can be reduced in one of three ways," he says. "You can modify the engine, treat the exhaust system or pretreat the fuel or air. Other options to reduce emissions from ships may include operational changes, such as speed reduction, as is being tried in the ports of Los Angeles and Long Beach.
"However, there is no silver bullet, no simple solution that will work for all vessel types and all locations. And, each of these options may be expensive for industry, a cost that ultimately gets passed on to the consumer."
Whatever solution is chosen, it may have unintended effects, Corbett says. "This is where my role as a policy analyst becomes important," he says. "Policy analysts help identify whether a problem merits action, we evaluate various options, and we work to measure the success of decisions."
Although Corbett is one of the leading researchers in the field of ship emissions, he describes himself more broadly as being one of a growing number of researchers bridging the gap between science and technology, environmental and economic concerns and public policy. He says his goal is to provide his students with the analytical skills they need to bridge this gap themselves, including an integrated assessment of interdisciplinary factors, uncertainty and risk analysis.
"That is why I am here," Corbett says. "I want to teach graduate students with interests in areas other than ship emissions how to become comfortable with new methods of quantitative analysis, which they can then apply to their own research and future work."
Jason Didden, a master's degree student in marine policy who took Corbett's course "Decision Tools for Policy Analysis" last semester, says he learned a "systematic process of decision making that ... will influence not only my research, but also how I make my own personal choices."
"The explicit treatment of uncertainty, which is often lacking in policy decision making, is perhaps the most important concept I will take from this course," Didden says.
Corbett collaborates with his colleagues in marine policy and with faculty interested in transportation and policy across the University. Through such collaborations, he says, he hopes to share with students the interdisciplinary technical, economic, decision and policy tools needed to help the maritime transportation system meet the challenges of the next decades.
--Kari Gulbrandsen