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:
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:
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:
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:
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.