Natural gas faces an uncertain future. As the most environmentally friendly fossil fuel, it is considered a potential “bridge fuel” in the transition to cleaner energy sources. In a new paper published on 16 December in Environment Research Letters, the authors discuss the controversial and uncertain role of natural gas in mitigating climate change.
At present, increased supply and cheaper prices have led to a global surge in natural gas usage, and the fossil fuel has, in fact, become a major contributor to greenhouse gas emissions: 20 per cent of global carbon dioxide emissions (CO2) emissions.
Friend or foe?
Although natural produces significantly fewer CO2 emissions than oil or coal — around 50 per cent less CO2 than coal — methane (CH4) leakage from infrastructure poses a significant and uncertain risk to the environment. Therefore, reducing carbon emissions by switching to natural gas can “create a hidden commitment to methane”, the authors write.
Methane leaks from wells, storage tanks, pipelines, as well as urban distribution pipes. These ‘fugitive’ methane emissions are difficult to measure, therefore, assessing the true impact of the gas on reducing greenhouse gas emissions is challenging.
The timeline of methane is another important factor to consider. While methane is indeed much more potent than CO2 and traps a lot more heat, it does not linger in the atmosphere for as long — decades versus centuries. This means that over 100 years methane is around 25 times more powerful but becomes 86 times more potent if only a 20-year period is considered.
In their analysis, Klemun and Trancik of Massachusettes Institute of Technology (MIT) discuss an important topic: CO2-equivalent climate policies for natural gas. The researchers looked specifically at the US electricity market and found that methane emissions associated with usage of the gas would have to be reduced by 30 to 90 per cent to meet the national target of reducing greenhouse gas emissions by 34 per cent by 2030.
But why is this range so big? They also discovered that methane leakage rates are widely distributed, highly variable, and just plain hard to measure. Overall, they estimate that methane leakage amounts to 1.5 per cent to 4.9 per cent of the gas that is produced and distributed.
Since leakage can occur at any stage — during processing, from storage tanks, or from distribution systems — various monitoring and mitigation strategies are required, which could prove difficult and expensive. From this perspective, renewable energy sources seem much more favourable and could help to meet the emissions targets without the need for complex methane leakage mitigation strategies, the authors suggest.
Future of natural gas in Europe
For the EU to achieve its “man on the moon moment” of becoming the first climate-neutral economy by 2050 — as outlined in the recently finalized European Green Deal — the gas industry will need to be transformed over the next few decades.
During negotiations last week, there were disagreements about whether natural gas should be included in the new proposal as a “clean” energy source.
Pascal Canfin, a French MEP, explained in a statement that natural gas is “neither included nor excluded in principle” in the final version of the deal and will not be considered a ‘pure green’ investment under any circumstance. But it will be part of the so-called taxonomy list. This means it can be used as part of a member state’s strategy if tests show “no significant harm” is caused and the target of zero net carbon emissions is met by 2050.
Natural gas as a ‘bridge fuel’
The merits of natural gas as a “bridge fuel” have not been fully verified. Nonetheless, switching to natural gas-fired power plants might provide a short- to medium-term solution for some countries seeking to phase out coal — particularly those heavily reliant on the black stuff.
Studies like this provide policymakers with, at the very least, some of the additional knowledge needed to make an informed choice between cleaning up methane emissions in the natural gas supply chain or focusing on carbon-free energy sources.
In the future, a mix of low and zero-carbon gaseous fuels, such as biogas, biomethane, hydrogen, and synthetic methane, is expected to replace natural gas. Until then, policymakers will have to toil between using less-favourable natural gas to keep up with energy demands or accelerating the transition to carbon-free energy sources like wind, wave, and solar power.
(1) Klemun, M.M. and Trancik, J.E. Timelines for mitigating the methane impacts of using natural gas for carbon dioxide abatement. Environmental Research Letters (2019). DOI: 10.1088/1748-9326/ab2577