Natural gas may be a temporary link to a clean-energy future

  • With 400 ppm of carbon dioxide in the atmosphere, it might be that we have crossed the carbon Rubicon.

    But if we are to have any chance to slow the rise of CO2 in the atmosphere and avoid the calamity that could follow – catastrophic warming, ocean acidification, changes in precipitation patterns and crop yields, extinctions of both animals and plants – there should be no doubt that we need to transition to a low-carbon energy system ASAP.

    No one thinks that doing so will be simple. Replacing a dirty, polluting power system is no easy thing, doubly so when it is also highly profitable for the corporations and governments that benefit from it – at least in the short term.

    Marcellus shale gas-drilling site, Lycoming County, Penn. (image via Nicholas A. Tonelli/Wikimedia Commons)

    Conventional green wisdom – the view held by new U.S. Energy Secretary Ernest Moniz, for example – says that replacing the dirtiest of power sources, such as coal, with cleaner power sources, such as natural gas, while not ideal would be an important step down the path to a low-carbon energy future.

    But do we really have time to take such small incremental steps? The quick answer is no.

    The logic of deploying so-called bridge fuels goes something like this: When it comes to carbon emissions there’s a hierarchy. Coal and tar sands are the dirtiest. Petroleum is a bit less dirty. Natural gas (conventional obtained, not from hydraulic fracturing) comes next, with roughly 40 percent the emissions of coal. Then comes nuclear power, with very low emissions at the site of generation (although mining pollution and possible accidents can change the calculus).

    If coal is the dominant energy source worldwide, as well as in the United States, then replacing coal power plants with natural gas ones, or at least building new power plants with natural gas even if the old coal ones still exist, will reduce emissions overall. Indeed, in the U.S., expansion of natural gas (combined with the Great Recession and slow recovery) means that greenhouse gas emissions have fallen a good deal in recent years.

    But here’s the problem: It’s too late for that. We are very likely too far down the road to catastrophic climate change that it simply isn’t prudent to rely on natural gas to replace coal. We need to commit to a far more rapid transition to a truly low-carbon energy system.

    Last year a paper in Environmental Research Letters took a look at what it will take to transform our energy system so that climate change damage is minimized. Natural gas isn’t part of the recipe.

    Though rapidly deploying low-carbon energy sources will do little to stop climate change damage through the first part of this century, the paper, by Ken Caldeira of Stanford University and technologist Nathan Myhrvold, says we must not delay in doing so. Without going into detail of all the calculations, Caldeira and Myhrvold conclude (emphasis added):

    Despite the lengthy time lags involved, delaying rollouts of low-carbon-emission energy technologies risks even greater environmental harm in the second half of this century and beyond. This underscores the urgency in developing realistic plans for the rapid deployment of the lowest-GHG-emission electricity generation technologies. Technologies that offer only modest reductions in emissions, such as natural gas and…carbon capture and storage cannot yield substantial temperature reductions this century. Achieving substantial reductions in temperatures relative to the coal-baed systems will take the better part of a century and will depend on rapid and massive deployment of some mix of conservation, wind, solar, and nuclear, and possibly carbon capture and storage.

    A couple things to consider in that:

    1. Conventionally sourced natural gas is what they are talking about when it comes to “modest reductions in emissions” – that is 40 percent or so of the emissions of coal, as we noted earlier. When hydraulic fracturing and shale gas come into the picture, the emission reductions are substantially less, though how much less varies widely depending on the analysis. And this is totally leaving aside other threats that fracking brings. Phrased another way, fracked natural gas doesn’t offer modest emission reductions compared to coal, it offers minimal emission reductions at best.
    2. Though this paper places nuclear power in the low-carbon energy mix, can we legitimately expect “rapid and massive deployment”? Compared to similar-sized large-scale wind and solar power projects, nuclear power plants take ages to be sited, approved and built. And that leaves aside the socioeconomic issues they present – the way in which the risk of catastrophic problems is passed off onto society as a whole, the impacts of mining uranium, and so on.

    Though the argument that we need nuclear power to provide base load power to deal with the intermittency of renewables is tempting to buy into, combined with energy storage (both current and to-be developed) renewables are simply a more sustainable option in many ways. Rather than spend billions of dollars on nuclear power, the money would be better spent deploying a similar amount of renewables with an improved transmission system capable of handling them, while also developing better energy storage.


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