Natural gas has frequently been described as a bridge fuel to a low-carbon energy future for at least a couple of promising reasons. Firstly, there's an abundance of the stuff, and secondly burning natural gas produces only about half the CO2 emissions as coal. In theory, at least, replacing coal-fired power stations with natural gas ones, and converting large trucks from diesel to natural gas, are ways to reap significant real-time climate benefits.
That said, however, there is a general Achilles-heel in the whole natural gas energy system, which is that it's leaky. Leaks occur not only in production of natural gas, but also in storage and transmission of it, and because natural gas is 80 percent methane (CH4), which is around 30 times more potent as a greenhouse gas than CO2, when it leaks, it's a big deal.
And it turns out, it's a bigger deal than previously thought. A new report by Stanford University finds that America's natural gas system is much more leaky than previously estimated, and maybe up to 50 percent more so than the EPA estimates. Of course, this is pretty significant because the benefits of burning lower-CO2 natural gas as an alternative to coal and oil, must be weighed against the deleterious effects of extensive methane leakage--but how bad is it? And is it bad enough that natural gas cannot be considered a viable bridge fuel to a lower carbon future?
Climate Progress cites the Stanford report in an article which addresses the methane leakage problem extensively, and provides data on various studies which suggest natural gas production, transmission and end-use leakage could be up to 7.1 percent of the natural gas extracted. At this rate, Climate Progress reports, it would take a natural gas power station 100 years to reap a greenhouse gas benefit over a coal fired plant--or as their headline points out--"by the time natural gas has a net climate benefit you'll likely be dead and the climate ruined." Uplifting stuff, indeed!
The Stanford report suggests one of the reasons the EPA has underestimated leakages is that emissions testing at wells and processing plants were based on operators participating voluntarily, and unsurprisingly, there haven't been too many volunteers. Stanford points out that for one study, the EPA asked 30 gas companies to cooperate with emissions-rates sampling, and only six of them let the EPA on site. Likely, the more unscrupulous operators are those most likely to have gone unaccounted for in determining accurate estimates.
Ideally, we would transition from coal to renewable energy without passing through natural gas as a bridge fuel, but let's face it, that's pretty unlikely to happen with low-cost natural gas production going on right now, and going through the roof. So, does this mean we're doomed with the apocalyptic prediction which Climate Progress suggests? Maybe not, because although leakage is higher than previously believed, it's not to say it has to be.
Indeed the World Resources Institute (WRI) seems to be a little more optimistic, in their article "Capturing The Fugitives: Reducing Methane Emissions from Natural Gas," WRI recognizes the risks of natural gas's so-called "fugitive emissions" problem, and concurs that leakage rates are currently in the range of 2 to 3 percent, and even as high as 7 percent. However, their own research finds that reducing methane leakage to 1 percent or less of total production, would provide a net climate benefit over any time horizon. Furthermore, WRI asserts, encouragingly, that a 1 percent leakage target is reachable through existing state and federal policies and with widespread adoption of existing and cost-effective technologies.
If WRI are right about this, it's great news--no new laws are required and no new technologies need to be invented. That being the case, the leakage problem may just boil down to effective enforcement. WRI explains the details of what can be done to mitigate leaks in their article--and perhaps one of the most significant points made is that leaked methane is in fact leaked profits; or put another way, the 7 percent of leaked methane is energy that could otherwise be sold by the companies who are extracting the natural gas. It seems obvious that off-gassing a salable product is foolish, and if such companies invested in the technology to hit the 1 percent leakage target, WRI states, it would take only three years or sooner for that investment to pay for itself.
Since natural gas is, by all accounts, projected to remain an important fuel in the energy mix for some time to come, there appears to be no excuse in failing to take advantage of its lower carbon benefits, by preventing unnecessary leakage. At least then, while advocating for increased use of renewable energy, natural gas could at least certainly be a better choice than coal and potentially a viable bridge fuel too.
Image Credit: Gerry Dincher
Phil Covington holds an MBA in Sustainable Management from Presidio Graduate School. In the past, he spent 16 years in the freight transportation and logistics industry. Today, Phil's writing focuses on transportation, forestry, technology and matters of sustainability in business.