By Steve Sawyer, Secretary General of the Global Wind Energy Council
The cornerstone of what the IEA has recently dubbed ‘The Golden Age of Gas’ is the exploitation of methane in tight formations through hydraulic fracturing, commonly known as hydro-fracking or just ‘fracking’. Through pumping millions of liters of water and chemicals (including known carcinogens) at high pressure through tight oil and gas formations, the rock is fractured and the hydrocarbons are released.
The question of the pollution of groundwater from this practice is much debated in the press as well as the scientific literature; but the issue of the impact of the leakage of methane from this process and its impact on total greenhouse gas emissions has taken a back seat up until now, although that may be changing.
Early studies of the subject raised serious cause for concern in relation to the extra leakage of methane, which is a much more potent greenhouse gas than carbon dioxide: more than 50 times more potent per molecule, over 20 years, although that diminishes over time as methane decays. The suggestion was made in a number of scientific papers that the net greenhouse benefit of burning coal over burning gas was nil, or perhaps even negative. This led the US EPA to dramatically revise the emission factors for certain parts of the process of producing gas in this fashion, raising the greenhouse gas impact of burning fracked gas up to close to the level of the most efficient coal plants. The industry of course fought back, and those regulations are under attack, and the US government (as well as, ironically, the European Commission have said ‘it’s not that bad’) has distanced itself from those studies; although their importance is much less in an economy which has no limits on greenhouse gas emissions.
The rule of thumb seems to be that the ‘break even’ point is somewhere between 2 and 3%, i.e., if leakage is below that level, there is some climate benefit from burning gas instead of coal: if it is higher, then you’d be better off burning coal than gas, purely in terms of greenhouse gas emissions. The precise number will depend on the coal plant that you’d be competing with and what it’s burning, as well as the type of gas plant being utilised.
The latest round of controversy stems from a paper published in the Proceedings of the National Academy of Science of the US in late July, where scientists whose institutions receive large contributions from the fossil fuel industry were allowed to study a number of gas fields selected by industry. This study prompted some articles such as “Fracking May Emit Less Methane Than Previous Estimates“; although that is not what the scientific paper says…it’s not even what the article says.
This has prompted a response from scientists at Cornell in the New York Times outlining both the shortcomings of the study and what can and cannot be concluded from it, and outlining the work that needs to be done to really get an empirical handle on this issue.
However, without much fanfare, what seems to me a landmark study, i.e., the actual measurement of methane from an airplane over a gas field, was released in early August in Geophysical Research Letters, where scientists from NOAA, the University of Colorado and others surveyed a large gas field in Utah and found leakage rates of between 6 and 11%!
This is one study of one field on one day, and as the authors themselves note, a lot more research needs to be done to assess the true state of affairs. On the basis of those results, however, we’d definitely be better off burning coal, at least in greenhouse gas terms. There are lots of other reasons not to burn coal, but it’s clear that the production of hydro-fracked natural gas needs to be strongly regulated and emissions reduced to the minimum…assuming it’s possible to reduce them substantially. Once we’ve computed the leakage in tons of carbon dioxide equivalent, spent the money to reduce the emissions as much as possible, and put a price on carbon, and then we’ll see how ‘cheap’ the gas is.
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