To account for the many variables, McElroy and his colleagues at SEAS developed a model that considers nine regions separately.
Their model identifies the relationship between the cost of electricity generation from coal and gas and the fraction of electricity generated from coal.
"When the natural gas prices are high, as they were 4 years ago, if the gas prices come down a little bit, it doesn't make any difference," explains lead author Xi Lu, a postdoctoral associate at SEAS. "But there's a critical price level where the gas systems become more cost-effective than the oldest coal-fired systems.
"If the gas price continues to drop, you'll continue to go down this curve so that you'll knock out not just the really ancient coal-fired power plants, but maybe some of the more recent coal-fired plants."
The model also predicts that a government-imposed carbon tax on emissions from power generation would drive a move away from coal.
"With a relatively modest carbon taxabout $5 per ton of CO2you could save 31 million tons of CO2 in the United States, and that would change the price of electricity by a barely noticeable amount," says McElroy.
The initial model was developed by Jackson Salovaara '11, an applied mathematics concentrator at SEAS. His work was recognized as the "best senior thesis" in the Harvard Environmental Economics Program, earning him the Stone Prize in May 2011.
Since then, the model has been "souped up," incorporating more sophisticated regional data analysis, and producing not just the findings on 2009 but also predictions for more recent years.
"While the data from 2011 are not yet available, based on the gas prices, we're making a confident prediction that there should be a continued shift from coal to natural gas in 2011 as compared to 20
|Contact: Caroline Perry|