Coal vs. Natural Gas

What Is Their Relative Short Term Climate Impact?

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Coal
Natural Gas
Coal
Natural Gas
Carbon Dioxide (CO2)
Methane (CH4)

Malfunctioning Methane Releases

Compressor
Pump
Valve

Intentional Methane Releases

Venting

Methane can only be visibly detected by imaging or high-end technological equipment.

Flaring

Inefficient flaring releases methane when gas is burned and converted to less potent CO2.

Climate Impact: US Methane Studies

Leakage Rate
Better
Same as Coal
Worse
End Use Combustion (CO2 Only)
0.0%
-50%
Gordon et al. (All pollutants)
0.2%
0%
Image of a methane plume detected via Carbon Mapper aerial survey

Climate Impact: US Methane Studies

Leakage Rate
Better
Same as Coal
Worse
End Use Combustion (CO2 Only)
0.0%
-50%
Gordon et al. (All pollutants)
0.2%
0%

Studies

+23%
+35%
+61%
Schneising et al.
1.2%–5.9%
+66%
Lin et al.
6.0%–8.0%
+135%
+183%
+215%
Photo by Jeremy Bishop on Unsplash

When gas is burned, it releases 50 percent less carbon dioxide into the atmosphere than coal.

Therefore, most people assume it has half the climate impact as coal.

But this doesn’t account for methane leaks.

Methane is a powerful climate pollutant

Over a 20-year period, it traps over 82.5 times more heat than carbon dioxide (CO2).

Methane leakage is caused by the malfunction of compressors, pumps, and valves...

...and by intentional releases (venting and flaring). Leakage is measured as a percentage of total natural gas produced.

When methane leakage from gas systems is included, the climate benefit of gas compared to coal flips. Methane leakage as low as 0.2% can bring gas' net GHG emissions on par with coal.

However, studies are finding that the EPA estimate of methane leakage is too low because it uses generic leakage factors and incomplete measurements from ground based equipment.

Studies find concerning levels of leakage in the United States

Technology mounted on airplanes and satellites has provided more accurate methane emissions measurement at larger scale.

Over the past 5 years, several studies using this technology have been published. They reported methane leakage rates from 1.2 to 11 percent.

Aerial measurements can vary widely because of super emitters—big leaks that disproportionately contribute to regional emissions.

This indicates that natural gas may not have any climate advantage over coal with the current rate of methane leakage.

Natural gas can achieve 50 percent lower climate impact if virtually all methane leakage is controlled.

Leaky gas is even worse than coal. Stopping gas from leaking can be done profitably by cutting waste and preventing it from escaping into the atmosphere.

Reducing US methane leakage from gas systems to minimum levels would be equivalent to taking all US cars off the road for a year.