How Power Plants Helped CO2 Emissions Drop
May 7th, 2010 by 
Carbon dioxide emissions dropped significantly in the United States in 2009. The economy played an obvious role; not so obvious was the influence of power generation and its increasing efficiency.
Emissions of CO2 have been trending down for the last decade by about 0.9 percent. But the 2009 drop was far more dramatic — seven percent — the largest decline since the Energy Information Administration began keeping energy data more than 60 years ago.
This tells us a lot about just how bad economic conditions were (As if we needed to be told!).
Compare the last decade to the previous one and you get the picture. Our gross domestic product grew about 3.3 percent from 1990 to 1999 then dropped by about half for the next decade, with much of the decline attributable to the recent miserable financial situation, according to a May 5 EIA report.
CO2 levels tell us about the economy because emissions are produced by power plants and transportation fuels. The better the economy the more energy we use and presumably the more CO2 we produce. For example, we consumed only 13,277 thousand barrels of petroleum per day for transportation in 2009, down from 14,287 thousand barrels per day two years earlier, a 7.1 percent drop.
But here is where it gets interesting. Even with the economy falling over the cliff, emissions should have grown a little bit, about 0.6 percent to 0.7 percent, based on past scenarios, so what changed? Why did CO2 emissions drop instead?
The EIA says power plant efficiency played a big role. We have been moving toward greater use of highly efficient natural gas-fired plants, which are less carbon intensive than coal-fired generation, our largest electricity source. From 2000 to 2008, the United States added about 120 gigawatts of natural gas combined cycle generation.
“If the emissions intensity had not changed and emissions had risen at the same rate as generation, they would have reached 456 million metric tons in 2009. Therefore, the increased efficiency of new generation capacity resulted in avoided emissions of 82 million metric tons of carbon dioxide,” EIA said.
Elisa Wood is a long-time energy writer whose work appears in many of the industry’s top magazines and newsletters. She is publisher of the Energy Efficiency Markets podcast and newsletter.
photo: Superburschi
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