The hot summer drastically increased Connecticut air pollution, more so because the state’s largest generator of emissions-free power had to close down operations because of the heat.
Connecticut had 27 days this summer of significantly decreased air quality, up from 14 days in 2011, according to an October report from the U.S. Environmental Protection Agency.
“It was simply the reason that we had more warm days this year than last year,” said Richard Burkhart, EPA environmental scientist.
The poor air quality — known as ground-level ozone, or smog — is caused when volatile organic compounds and oxides of nitrogen emitted from cars, power plants, household cleaners, and print shops react in the sunlight. This issue is compounded when the winds blow up from New York City and northern New Jersey, which has a higher concentration of people and emits significant more pollutants.
Smog is worse in the summer because as temperatures rise, electricity consumption increases as more people turn on air conditioners and other equipment. This consumption increase strains the electrical system, and utility companies are forced to rely on non-regular power plants, which tend to use fuels such as oil and coal that emit more nitrogen oxides than regular power plants.
“On very hot days, you get a lot of oxides of nitrogen from power plants,” Burkhart said.
The problem is exacerbated on hot days because those days tend to be sunnier, which is key in the chemical reaction causing smog.
Connecticut had 25 days with temperatures 90 degrees or higher this summer, compared to 15 days in summer 2011.
The extended heat waves this summer also caused the water temperatures in Long Island Sound to rise, which impacted the operations of the nuclear Millstone Power Station in Waterford. Taking Millstone off-line forced the use of more peaker plants which contributed to poor air quality.
One of Millstone’s two reactors cools its systems using water from the Sound, but that water temperature can’t exceed an average of 75 degrees in a 24-hour period for safety reasons.
On Aug. 12, for the first time in the 37-year operating history of that Millstone reactor, the Sound temperature rose above 75 degrees, and the reactor had to be shut down for 12 days.
“We had to wait until the temperature went down, and we wanted to make sure it would stay down,” said Ken Holt, spokesman for Millstone.
Millstone typically provides about 45 percent of Connecticut’s power, but with the one reactor shut down for nearly two weeks, that supply dropped closer to 30 percent. The nuclear power emits no air pollution, as the only hazardous byproduct of the nuclear reaction is spent uranium, which is self-contained and stored onsite at Millstone.
Once that Millstone unit went down, the state’s electric utilities had to rely on non-regular, more polluting power plants to make up the difference, compounding the air quality problem.
Seeing rising temperatures as a problem going forward, Millstone is doing an analysis on its reactor to see if it can safely operate at a higher temperature, said Holt.
Despite 2012’s problems with hot temperatures and poor air quality, EPA sees it as an aberration in a positive trend toward better air quality.
“The long-term trends are really good, and they have been for the last few years,” said Dave Deegan, EPA spokesman.
In the first year EPA started tracking the data, 1983, Connecticut had 103 smog days, which was the worst year in recorded history. The next year saw a significant decrease to 63 smog days.
In the 1980s, Connecticut averaged 59 smog days per year; in the 1990s, there were 39 days on average; and the 2000s saw 29. The last three years averaged 22.
Over the years, power plants have gotten better about producing fewer pollutants, said Burkhart, and the government has gotten better about regulating pollution from everyday items such as household paints.
“Overall, the trend is significantly downward,” Burkhart said.
