A synthetic chemical widely used in the manufacture of computers and flat-screen televisions is a potent greenhouse gas, with 17,000 times the global warming effect of carbon dioxide, but its measure in the atmosphere has never been taken, nor is it regulated by international treaty.
The chemical, nitrogen trifluoride (NF3), could be considered the "missing greenhouse gas," atmospheric chemists Michael J. Prather and Juno Hsu of UC Irvine wrote in a paper released June 26 in the journal Geophysical Research Letters. "With the surge in flat-panel displays, the market for NF3 has exploded."
The rapid growth in production alarms some climate scientists. In the atmosphere it has a life of 550 years, according to calculations by Prather and Hsu.
When the Kyoto Protocol, the 1997 international global warming treaty, was negotiated to control the rapid rise of planet-warming gases, NF3 was a niche product used in modest amounts in the semiconductor industry.
At the time, computer chip manufacturers used perfluorocarbons to clean the vacuum chambers where integrated circuits were made. But about two-thirds of the PFCs escaped into the atmosphere, contributing to the greenhouse effect, a warming of the Earth's surface.
Reacting to environmental concerns, the industry sought a substitute -- and estimated that NF3, though it had greater potential for global warming, was less likely to escape into the air. "We moved into manufacturing NF3 for environmental reasons," said Corning F. Painter, vice president of global electronics for Air Products in Allentown, Pa., the world's leading producer. The company received a 2002 Climate Protection Award from the Environmental Protection Agency for its transition.
Last year, it announced a major production expansion at its U.S. and Korean plants. About three-quarters of the chemical is now used to manufacture computer microchips; the rest is used to make liquid crystal display panels on flat-screen televisions, Painter said.
Overall, world production of NF3 is likely to reach 8,000 tons a year by 2010, Painter said. That is the equivalent of more than 130 million metric tons of carbon dioxide. By comparison, according to the UC Irvine paper, a major coal-fired power plant producing 3,600 megawatts of electricity emits as much as 25 million metric tons of carbon dioxide a year.
Air Products officials say that about 2% of NF3 is emitted during manufacturing and that much of that is burned off before reaching the atmosphere.
