Why gas is not a bridge fuel

When gas is burnt, it generates less CO2 than other fossil fuels. This is why it has been labelled as a “clean fossil fuel”. However, a crucial element needs to be taken into consideration: along the supply chain, from extraction to transport, gas leaks occur.

This so-called “natural” gas consist of about 90% methane, which has a global warming capacity 86 times greater than CO2 the rst 20 years after its release into the atmosphere. Methane leaks can reach 10.1 % (unconventional gas) and 5.96 % (conventional gas) during the extraction process and transport. Once on the methane tanker, losses can account for 0.25 % per day of transit.

A series of studies have shown that the amount of full life cycle emissions of methane do not compensate for the CO2 that would be avoided when switching from coal- to gas-fired electricity generation. These numbers show a switch to gas would not be bene cial to the climate, nor would we reach the internationally agreed goal to remain below a 2°C increase in global temperature.

Moreover, as gas demand is falling, there is a high risk for new gas infrastructure to become stranded assets. As the EU supports projects like these through public-private partnerships (PPP), assuming the risk, it is the public sector (and thus the taxpayer) that pays the bill if the project turns out not to be pro table.

Altogether, gas is not a bridge fuel. By allowing new gas infrastructure to be built, the EU is forcing its citizens into another couple of decades of unnecessary fossil fuel dependence, and to invest in risky assets diverting money away from a cleaner future.

Text from the flyer/map Global Gas Lock-in.

Schematic geology of gas resources (Graphic: IEA)

Increasing methane emissions

Figures from the text Methane emissions by Howarth, 2016.

Green “reference” line shows predicted warming with current emissions. “CO2 measures” line indicates that warming will continue for several decades even if CO2 emissions are reduced now. “CH4 & BC measures” shows that reducing emissions of methane and black carbon can immediately slow global warming. The best outcome is when both methane and carbon dioxide emissions are reduced (“CO2 + CH4 + BC measures”). Source: Shindell et al. 2012, Science 335: 183-189).

Both direct emissions of carbon dioxide and unburned methane emissions expressed as carbon dioxide equivalents, expressed per unit of energy produced. For each fuel, the best estimate for methane emissions is used. Methane compared to carbon dioxide over a 20-year time period following emission to the atmosphere. Vertical bars illustrate the moste probable range of values for shale gas and conventional gas. Source: Howarth 2015, Energy & Emission Control Technologies.

Imagery indicates the increase is largely from increased emissions in the shale gas & oil fields of the U.S. between 2006-2008 and 2009-2001. Source: Schneising et al. 2014, Remote sensing of fugitive methane emissions from oil and gas production in North American tight geologic formations. Earth’s Future 2: 548-558.

Satellite imagery shows methane concentration geographically over time, with warmer colors indicating higher concentrations. Data show a global increase in methane over time since 2008, particularly in the Northern Hemisphere (right; 0 is the equator, 1 & -1 are the poles). Source: Schneising et al 2014, Remote sensing of fugitive methane emissions.

Methane and Global Warming in the 21st Century

Watch this webinar if you want to know about the science and politics of methane. Webinar with Robert Howarth, 2018.

Gas leakage in fossil fuel extraction

The leakage of gas during the extraction of fossil fuels is normally not visible. Experts have made them visible with infrared cameras in an oil extraction site in Veracruz, Mexico. More information in Spanish language at Allianza Mexicana contra el Fracking. December 2017.

The debate in scientific articles

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Public institutions and industry


Methane and Dual Accounting at the UNFCCC (LINGO, April 2018)

Methane emissions and global warming

Robert W. Howarth on the dangers of climate change and why/how we need to reduce methane emissions in the very near future to stop global warming. June 2017. Subtitles in Spanish.