A major new study blows up the whole notion of natural gas as a short-term bridge fuel to a carbon-free economy.
Natural gas is mostly methane (CH4), a potent heat-trapping gas. If, as now seems likely, natural gas production systems leak 2.7% (or more), then gas-fired power loses its near-term advantage over coal and becomes more of a gangplank than a bridge. Worse, without a carbon price, some gas displaces renewable energy, further undercutting any benefit it might have had.
Fifteen scientists from some of the leading institutions in the world — including Harvard, NOAA and Lawrence Berkeley National Lab — have published a seminal study, “Anthropogenic emissions of methane in the United States.” Crucially, it is based on “comprehensive atmospheric methane observations, extensive spatial datasets, and a high-resolution atmospheric transport model,” rather than the industry-provided numbers EPA uses.
Indeed, the Proceedings of the National Academy of Sciences study by Scot Miller et al takes the unusual step of explicitly criticizing the EPA:
The US EPA recently decreased its CH4 emission factors for fossil fuel extraction and processing by 25–30% (for 1990–2011), but we find that CH4 data from across North America instead indicate the need for a larger adjustment of the opposite sign.
How much larger? The study found greenhouse gas emissions from “fossil fuel extraction and processing (i.e., oil and/or natural gas) are likely a factor of two or greater than cited in existing studies.” In particular, they concluded, “regional methane emissions due to fossil fuel extraction and processing could be 4.9 ± 2.6 times larger than in EDGAR, the most comprehensive global methane inventory.”
This suggests the methane leakage rate from natural gas production, which EPA recently decreased to about 1.5%, is in fact 3% or higher.
This broad-based look at methane emissions confirms the findings of 3 recent leakage studies covering very different regions of the country:
- NOAA researchers found in 2012 that natural-gas producers in the Denver area “are losing about 4% of their gas to the atmosphere — not including additional losses in the pipeline and distribution system.”
- A 2013 study by NOAA found leaks from oil and gas exploration and extraction in the L.A. basin representing “about 17% of the natural gas produced in the region, similar to the leak rate estimated by the California Air Resources Board using other methods.” Almost all the gas produced in the basin is “associated” with oil production (rather than, say, fracked). Associated gas is still about a fifth of total U.S. gas production.
- Another 2013 study from 19 researchers led by NOAA concluded “measurements show that on one February day in the Uinta Basin, the natural gas field leaked 6 to 12 percent of the methane produced, on average, on February days.” The Uinta Basin is of special interest because it “produces about 1 percent of total U.S. natural gas” and fracking has increased there over the past decade.
The comprehensive nature of this new study strongly suggests these earlier findings were not anomalies, as some have suggested.
Indeed, all of these findings taken together vindicate the concerns of high leakage rates raised by Cornell professors Howarth, Santoro and Ingraffea, which I reported on back in 2011. I asked Ingraffea to comment on the new study. He wrote:
The results presented by Miller and his team are another serious challenge to an “all of the above” energy policy that relies on negotiated estimates of methane emissions, rather than actual and representative emission measurements, while at the same time claiming serious concern about climate change. A growing series of regional, top-down measurements by this team and others, now on a national scale, is proving to be a more rational approach to accounting for the highly skewed distribution of methane emission sources.
He added, “That methane bridge is starting to crack.”
We have seen a number of cracks this year in the methane bridge — bringing it to the point of collapse. The Intergovernmental Panel on Climate Change (IPCC) reported recently that methane is a far more potent a greenhouse gas than we had previously realized, some 34 times stronger a heat-trapping gas than CO2 over a 100-year time scale — and 86 times more potent over a 20-year time frame.
With methane having both a higher leakage rate and higher global warming potential than previously thought, the notion of methane as a bridge fuel is falling apart.
Yes, it’s true a recent study finds the best-fracked wells have low methane leak rates — but that study ignored the super-emitters that are responsible for the bulk of the fugitive emissions.
And remember, for natural gas to be a bridge fuel to a carbon-free future (rather than a detour around it), gas must replace coal only, rather than replacing some combination of coal, renewables, nuclear power, and energy efficiency — which is obviously what will happen in the real world absent a price on carbon pollution. The most comprehensive modeling to date, by fourteen teams from different organizations, found that abundant and cheap natural gas has little net impact on U.S. CO2 growth (especially post-2020) compared to the case of low shale gas penetration precisely because it displaces carbon-free energy. Globally, the International Energy Agency finds a dash to gas would destroy a livable climate.
Finally, natural gas makes little sense as a short-term sustainability play, since we know that each fracked well consumes staggering amounts of water, much of which is rendered permanently unfit for human use and reinjected into the ground where it can taint even more ground water in the coming decades. That’s particularly worrisome considering that fossil fuels destroy the climate and accelerate drought and water shortages.
With this most recent study, our understanding of the limitations of natural gas is now fairly complete. Natural gas is not a bridge to a carbon-free or climate-safe future. In fact, absent both a serious price for carbon and very strong, enforceable national regulations on leakage, natural gas is a gangplank.