Regional changes in CO2 emissions from US power sector 2008-2009

When the economic recession hit the US in 2009, at least one good thing seemed to have come from it: a reduction in carbon emissions to levels not seen since 1996.

But as it turns out, the recession wasn’t the main cause of the reduction. It was the competitive pricing of natural gas versus coal that was responsible for more than half the decrease in CO2 emissions.

Less emissions same electric bill

And according to an econometric model by researchers from the Harvard School of Engineering and Applied Sciences, a small carbon tax could cut emissions even further, with a negligible impact on consumer’s electric bill.

Usually coal power accounts for a bit under half of the country’s electricity production. But when natural gas prices plunged by 4 cents/kWh in 2009 compared to 2008, thanks to an increase in production from shale, a large part of the coal power was displaced by power generation from natural gas.

Coal versus natural gas

In the US the power sector is responsible for about 40 per cent of all carbon emissions. Since coal power releases about twice as much CO2 into the atmosphere as power from natural gas, the large scale switch in 2009 resulted in a decrease in CO2 emissions of as much as 8,76% relative to 2008.

The model that appeared in the journal Environmental Science and Technology shows that there is a critical level at which gas systems become more cost-effective than older coal-fired power plants. When gas prices drop even more, recent coal-fired plants are knocked out as well.

Carbon tax

That is why a slight government-imposed carbon tax on carbon emissions from power generation would drive the power sector away from coal. According to Michael B. McElroy lead researcher of the study a modest carbon tax of about 5 dollars per ton of CO2 would result in a decrease of 31 million tons of carbon emissions.

The research team has been working on improving the model since 2009 so that it can also produce predictions of more recent years. And while the data for 2011 are not yet available McElroy states that, based on the gas prices, there should be a continued shift from coal to natural gas, even though previous research shows a continuing upward trend in carbon emissions.

Money

So while the shift from coal power to power generation from natural gas was responsible for more than have the reduction in carbon emissions in 2009 and the economic recession for much of the rest, it appears that they both have a common denominator: money.

As is often seen, when money is involved, whether the lack of or the promise of an increased profit, emissions reduction seems doable. But at least in the case of a shift from coal to gas, everybody wins. Or do we?

© Jorn van Dooren | www.bitsofscience.org