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Why there’s more to a fall in US emissions than meets the eye

  • 23 Aug 2012, 10:00
  • Robin Webster and Ros Donald

US carbon dioxide emissions fell to a 20-year low at the beginning of 2012, partly due to lower natural gas prices as a result of domestic production of shale gas -  a fact that hasn't escaped the attention of the press. But does this signify anything for the US's ability to reduce its energy-related emissions in the future? And what does it mean for the global picture?

The figures, which the US Energy Information Administration (EIA) released on 1st August show carbon dioxide emissions from the US energy sector during the first quarter of 2012 (January to March) were the lowest for that part of the year since 1992. See the graph below:

Screen Shot 2012-08-22 At 17.03.02

The EIA says this is because of three things: an usually mild winter, reduced demand for petrol and a decline in the burning of coal for electricity, "due largely", it says, "to historically low natural gas prices".

Unsurprisingly, this last point has attracted the most media attention. Natural gas produces about half the volume of emissions that coal does when burnt, so the boom in US production of shale gas and subsequent switch away from burning coal for electricity in the States has driven down carbon dioxide emissions. A breakdown of energy-related emissions in the States over the last few years illustrates this:

Stacked Bar

US Carbon dioxide emissions from energy for the first quarter of the year. Chart made using data sourced from Chapter 12 of EIA's June Monthly Energy Review

An example for the world?

The press has been particularly interested in shale gas's contribution to falling emissions in the USA, especially as several commenters have touted the fuel as a solution to climate change. Alan Riley, a law professor at City University, for example recently suggested the example of the US could pave the way for a global switch from coal to shale gas.  He says:

"By developing shale gas as a replacement fuel for coal we retrieve the prospect of blunting - and possibly reversing - the upward climb of carbon dioxide emissions."

But how far would the switch take us? In a blog for Council on Foreign Relations, energy expert Michael Levi puts some numbers to the question. After the Copenhagen Summit in 2009, the US pledged to reduce its greenhouse gas emissions to 17 per cent below 2005 levels by 2020. Leaving other greenhouse gases aside, Levi calculates that if shale gas were to displace coal entirely in the US, US carbon dioxide emissions would fall to 24 per cent below 2005 levels.

But that's a pretty tall order - requiring shale gas production to double in the US. And to go beyond the 2020 goals to the US's 2025 and 2030 aspirations of a 30 and 42 per cent reduction in greenhouse gases would require both the successful deployment of carbon capture and storage technology and for shale gas to completely replace oil as well.

There is also the question of whether the recent fall in US emissions will develop into a long-term trend or not. As the Associated Press puts it:

"...changes in the marketplace - a boom in the economy, a fall in coal prices, a rise in natural gas - could stall or even reverse the shift. For example, US emissions fell in 2008 and 2009, then rose in 2010 before falling again last year."

In the absence of government policy measures, it's hard to be sure what will happen. Levi concludes:

"simply moving from coal to gas is not a substitute for broader policy, at least not if the United States wants to realize the sorts of emissions cuts that both Barack Obama and John McCain talked about only four years ago."

Exporting emissions

Finally, what about the global picture? The International Energy Agency recently released figures showing that global emissions of carbon dioxide from the burning of fossil fuels reached a record high in 2011.

New Scientist magazine argues that the fall in US carbon dioxide emissions isn't really a fall - because "in reality the emissions have simply been exported". This is because while US coal consumption has fallen, it's not producing any less coal. US production of coal is holding steady and it's exporting the surplus:

Screen Shot 2012-08-22 At 17.06.59

Source: EIA June monthly review, p.82

New Scientist states that "the surplus [coal] is being sold to Asia" - although in fact it's worth noting the US is still exporting quite a lot more coal to Europe:

Screen Shot 2012-08-22 At 17.09.52

Source: EIA, June 2012

The EIA attributes the growth in coal exports to "rising spot natural gas prices in Europe" and says the growth in Asia is partially due to "[a] series of international coal supply disruptions" in 2011.

The New Scientist may not be entirely correct - just because the US is exporting coal elsewhere, it doesn't necessarily mean that other countries are burning more coal than they would otherwise have done. But the global upwards trend in emissions is hardly reassuring.

All of this creates considerable uncertainties. That's without even discussing the potential role of fugitive methane in driving up greenhouse gas emissions associated with shale gas. There's also the possibility that shale gas could  outcompete renewables, not coal. Overall, it's hard to be convinced yet that shale gas could really set the global trajectory for emissions downwards.

 

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