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Carbon dioxide emissions from electricity generation have decreased by 32 percent in the past 15 years in the U.S. due to the shift from coal to natural gas and renewables, a recent report from the U.S. Energy Information Agency (EIA) found.
In 2019, the electric power sector produced 1.724 metric tons of CO2, compared to 2.544 MMmt in 2005. The underlying reason for that “CO2 emissions associated with generating energy from coal and natural gas differ because of differences in the fuels themselves – coal has more carbon content per unit of energy. The amount of CO2 produced when a fuel is burned depends on a fuel’s carbon content,” the report indicates. Coal produces 209 pounds of CO2 per million British thermal units, while natural gas produces 117 MMBtu when burned.
In 2005, coal made up 50 percent of U.S. electricity generation, but declined to just 23 percent by 2019. In contrast, natural gas use increased from 19 percent to 38 percent during that time period.
The EIA predicted in its Short Term Energy Outlook that rising natural gas prices will lead to more coal-fired generation for the next few years, but also that in 2022 both coal and natural gas will lose ground to renewable sources of energy, which are on the rise and have also contributed to reducing emissions.
The amount of electricity generated by renewables rose from 9 percent in 2005 to 18 percent in 2019, in large part due to growth in wind and solar power. Nuclear power, which is also zero-emission, has remained stagnant at about 20 percent.
The EIA also found that the shift from coal to natural gas had a bigger impact on emissions reductions than did renewables. The increase in natural gas generation was responsible for 65 percent of the 819 million MMmt decline in CO2, while renewables accounted for 30 percent.
The future of power generation is a topic of debate nationally and in Pennsylvania, as Gov. Tom Wolf plans for the state to join the Regional Greenhouse Gas Initiative, a consortium of 11 northeast states in 2022 that sets a regional cap on carbon dioxide emissions from power plants and requires operators to buy credits for each ton emit, with the goal of addressing climate change. But the EIA report makes it clear that sources of fuels used for power generation plays a large role, as will future improvements in technology and generation efficiency.