Dear EarthTalk: Do airplanes contribute significantly to air pollution?
—Neil Gladstone, New York, NY
Airplanes do indeed create a great amount of air pollution. According to the Natural Resources Defense Council (NRDC), a non-profit environmental group, "airport air pollution is similar in scope to that generated by local power plants, incinerators, and refineries, yet is exempt from rules other industrial polluters must follow." Major airports, says NRDC, rank among the top 10 industrial air polluters in cities such as Los Angeles, Washington and Chicago. The hundreds of thousands of airplanes taking off, landing, taxiing and idling each day across the country emit contaminants into the air and ground which have been linked to a wide range of human health problems, including asthma and cancer.
Beyond local environmental effects, air travel is contributing significantly to global warming. A 1999 report by the Intergovernmental Panel on Climate Change (IPCC) found that aircraft are responsible for 3.5 percent of greenhouse gas emissions worldwide; this could increase to 10 percent by 2050 as the popularity of air travel rises. Meanwhile, contrails—those vapor condensation trails you see overhead that are formed when airplanes fly at high altitudes through extremely cold air—could be contributing to global warming as they turn into high thin cirrus clouds and trap heat from incoming sunlight within the atmosphere.
A recent agreement to cut 37 daily peak-hour arrivals at America's busiest airport, Chicago's O"Hare, should help to not only ease congestion and reduce delays but also to improve local air quality and reduce greenhouse gas emissions. Unfortunately, because of the increasing popularity of air travel, 60 of the 100 largest U.S. airports are proposing building more runways, thus expanding rather than reducing activity.
Because airplanes are considered part of interstate commerce, they are not subject to local and state pollution laws. Furthermore, the Federal Aviation Administration has the potentially conflicting responsibilities of monitoring pollution while promoting air travel.
In lieu of government regulation to curb airplane emissions, though, economics sometimes prevail. In the wake of 9/11, consumers have been skittish about air travel, while fuel prices have risen to unprecedented levels. Ailing airlines are left with no choice but to scale back on flights as well as on engine idling, in turn benefiting the environment. Analysts estimate that Delta Air Lines" voluntary reduction of engine idling, for instance, has cut ground-level emissions from its planes by as much as 40 percent.
Meanwhile, NRDC promotes taxes on jet fuel as a way to encourage airlines to increase their efficiency, and encourages consumers to opt for alternative modes of transportation, such as high-speed rail when available, especially for shorter distances. "Consumers can also help," says the group, "by demanding that airports be subject to the same rigorous standards and reporting requirements as their industrial neighbors."
Dear EarthTalk: What is "biomass energy," and where in the world is it used?
—Kourosh Khazaii, Vancouver, BC
Biomass energy is power generated by burning any organic plant matter, including wood. As such it was perhaps humankind's earliest source of fuel. Wood is by far the most widely used biomass energy source, but other plants are also used, as are residues from agriculture or forestry and the organic components of municipal and industrial wastes.
Environmentalists are enthusiastic about expanding the use of biomass energy because it is fundamentally a renewable energy source and has the potential, if widely used, for greatly reducing the greenhouse gas emissions that contribute to global warming. While the burning of biomass fuels generates carbon dioxide (CO2), the leading greenhouse gas, new plants grown for biomass remove CO2 from the atmosphere. So as long as biomass energy sources continue to be replenished, their net CO2 emissions will be zero.
Biomass, because it is available on a recurring basis, is the world's most plentiful fuel source, and it is second only to hydropower in efficiency. Thus it is a very viable alternative to burning fossil fuels. Farmers around the world are now cultivating fast-growing trees and grasses specifically for biomass energy use.
Developing countries, especially those in Asia, Latin America and Africa, are currently the primary users of biomass as fuel, mainly because in many locales they lack access to other forms of energy. In the developing world, biomass makes up almost a third of total energy use. By contrast, the U.S. uses biomass for only four percent of its total energy supply.
Many countries are making concerted efforts to increase their use of biomass. Australia is generally recognized as the leader in developing biomass projects, due to the close cooperation there between government agencies, research facilities and industry. Britain is also working on some significant biomass projects, including the establishment of power stations fueled by fast-growing crops.
The International Energy Association reports that biomass has the potential to supply 40 percent of the world's energy needs. Studies by the Shell International Petroleum Company and the Intergovernmental Panel on Climate Change are equally if not more optimistic and project that biomass could satisfy between one-quarter and one-half of the world's demand for energy by the middle of this century. This projection implies a world full of "bio-refineries," where plants provide many of the materials we now obtain from coal, oil and natural gas.
Looking ahead, some analysts have begun to talk about a "carbohydrate economy" in which plants would be a major source of not only electricity and fuels, but also construction materials, clothes, inks, paints—even industrial chemicals.
CONTACTS: Biomass Energy Research Association, (800) 247-1755, www.bera1.org; International Energy Association, (011) 33-1-40-57-65-00, www.iea.org; Shell International Petroleum Company, (888) GO-SHELL, www.shell.com; Intergovernmental Panel on Climate Change, www.ipcc.ch.