Increases in electricity generation from non-carbon power sources since 2005 also had an effect on CO2 emissions from power generation. State policies and federal tax incentives that encouraged adoption of renewables have driven this growth. iStock photo.
Most changes in US CO2 emissions have been in the power sector
US electric power sector carbon dioxide emissions (CO2) have declined 28 per cent since 2005 because of slower electricity demand growth and changes in the mix of fuels used to generate electricity.
EIA has calculated that CO2 emissions from the electric power sector totalled 1,744 million metric tons (MMmt) in 2017, the lowest level since 1987.
In the United States, most of the changes in energy-related CO2 emissions have been in the power sector. Since 2005, as power sector CO2 emissions fell by 28 per cent, CO2 emissions from all other energy sectors fell by only 5 per cent.
Slower electricity demand growth and changes in the electricity generation mix have played nearly equal roles in reducing US power sector CO2 emissions.
US electricity demand has decreased in 6 of the past 10 years, as industrial demand has declined and residential and commercial demand has remained relatively flat. If electricity demand had continued to increase at the average rate from 1996 to 2005 (1.9 per cent per year) instead of its actual average rate of -0.1 per cent per year, US power sector CO2 emissions in 2017 would have been about 654 MMmt more than actual 2017 levels.
If the mix of fuels used to generate electricity had also stayed the same since 2005, US power sector CO2 emissions would have been another 645 MMt higher in 2017.
The power sector has become less carbon intensive as natural gas-fired generation displaced coal-fired and petroleum-fired generation and as the non-carbon sources of electricity generation—especially renewables such as wind and solar—have grown.
The substitution of natural gas for other fossil fuels has largely been market driven, as ample supplies of lower-priced natural gas and the relative ease of adding natural gas-fired capacity have allowed it to pick up share in electric power generation in many markets.
In 2016, natural gas generation surpassed coal as the largest source of electricity generation.
Under Illinois’ current plan to increase the amount of renewable power on its grid, the state will reduce the electricity sector’s carbon emissions by 22 percent by 2030, according to an analysis released Oct. 24 by the Union of Concerned Scientists. If Dynegy-Vistra closes six additional economically-struggling coal plants in the same period, the state could reduce its emissions by as much as 48 percent by 2030 and prevent nearly 1,000 premature deaths because of less air pollution.
“If Illinois wants to be a climate leader, wants to protect its residents’ health and wants to clean up its air, then we must close additional coal plants and close them faster,” said Jessica Collingsworth, report co-author and lead Midwest energy policy analyst and advocate.
Because the coal generation would be replaced with increased investments in energy efficiency, Illinoisans could see their electricity bills drop by $93 per year by 2030, according to the study.
“Retiring more coal plants, beyond what will be shut down because of current policies, doesn’t just make the air cleaner and our lungs healthier, it means savings for our pocketbooks, too,” said James Gignac, report co-author and lead Midwest energy analyst.
Increases in electricity generation from non-carbon power sources since 2005 also had an effect on emissions from power generation. This growth has been driven largely by state policies and federal tax incentives that encouraged adoption of renewables.
In 2005, non-carbon sources accounted for 28 per cent of the U.S. electricity mix. By 2017, that share had grown to 38 per cent. Almost all of this growth was in renewables, including wind and solar, as shares for other non-carbon sources such as nuclear and hydroelectricity remained relatively flat.