Sep 28 2023
Coal vs Natural Gas
In the last 18 years, since 2005, the US has decreased our CO2 emissions due to electricity generation by 32%, 819 million metric tons of CO2 per year. Thirty percent of this decline can be attributed to renewable energy generation. But 65% is attributed to essentially replacing coal-fired plants with natural gas (NG) fired plants. The share of coal decreased from 50% to 23% while the share of NG increased from 19% to 38%. Burning coal for energy released about twice as much CO2 as burning NG. Plus, NG power plants are more efficient than coal. The net result is that NG releases about 30% of the CO2 per unit of energy created as does coal.
But – the picture is more complicated than just calculating CO2 release. The implications of a true comparison between these two sources of energy has huge implications for our attempts at reducing climate change. It’s clear that we should phase out all fossil fuels as quickly as possible. But this transition is going to take decades and cost trillions. Meanwhile, we are already skirting close to the line in terms of peak warming and the consequences of that warming. We no longer have the luxury of just developing low carbon technology with the knowledge that it will ultimately replace fossil fuels. The path we take to get to net zero matters. We need to take the path that lowers greenhouse gas (GHG) emissions as quickly as possible. So when we build more wind, solar, nuclear, hydroelectric, and geothermal plants, do we shut down coal, natural gas, or perhaps it doesn’t matter?
If we look just at CO2, it’s a no-brainer – coal is much worse and we should prioritize shutting down coal-fired plants. This may still be the ultimate answer, but there is another factor to consider. NG contains methane, and methane is also a GHG. Per molecule, methane causes 80 times the warming of CO2 over a 20 year period. So any true comparison between coal and NG must also consider methane. (A little methane is also released in coal mining.) But considering methane is extremely complicated, and involves choices when looking at the data that don’t have any clear right or wrong answers.