Dive Brief:

• Rapid coal plant retirements led to a 10% decrease in power sector carbon emissions in 2019, according to preliminary estimates from the Rhodium group released Tuesday.

• The group credited the reduction "almost entirely" to coal's decline in the power sector — electric generation from coal dropped a record 18% from 2018 to 2019. Reduced coal power from 2005 to 2016 had significant downstream pollution impacts on human lives, crop yields and the climate, according to a report released Monday by the University of California San Diego (UCSD). The latest drops in coal generation will likely lead to more lives and crops saved, according to the UCSD report's author.

• Increased natural gas generation offset some of these favorable results, according to both studies, though broadly, the replacement of coal with natural gas and renewables is responsible for the decline in power sector greenhouse gas emissions (GHGs) and resulting environmental benefits. Despite power sector improvements, building and transportation sector emissions rose and remained flat, respectively, leading to an overall emissions decrease of 2.1% in 2019.

Dive Insight:

Though carbon emissions from the power sector rose slightly in 2018, a continued trend of declining coal power led to improved results in 2019. Natural gas replaced the majority of the lost generating capacity from coal, adding around 40 million metric tons of carbon emissions to the sector. But coal retirements cut emissions by 190 million metric tons, creating a net decrease of 150 million metric tons in the power sector.

Meanwhile, mass coal plant retirements between 2005 and 2016 saved an estimated 26,610 lives, 570 million bushels of corn, wheat and soybeans, and reduced regional climate impacts, according to the UCSD report. Smog-causing pollutants such as sulfur and nitrogen, as well as carbon monoxide and heavy metals are some of the "short-lived climate pollutants," that don't necessarily stay in the atmosphere but instead linger regionally, and are specific to coal power, the report noted.

The Rhodium report's results for 2019 could potentially lead to another 0.9% change in the mortality rate, and a 4-7% increase in crop yields for areas closest to the plants, assuming the reduction in coal plant emissions between 2017 and 2019 are caused by plant shutdowns rather than reduced production, UCSD report author Jennifer Burney, an associate professor at the university's School of Global Policy and Strategy, told Utility Dive in an email. 

"Either way we'd expect less pollution, but the first case is obviously closer to the study for extrapolation purposes," she said. "The total aggregate numbers would depend on where the plants are, but I would imagine that the numbers would be similar to in the paper and in similar regions."

Though net U.S. GHG emission declined overall in 2019, the pace of decarbonization will need to pick up if the country is to meet the Paris Agreement targets — a 26% to 28% decline from 2005 emissions by 2025.

Based on Rhodium's preliminary results, the U.S has reduced emissions 12.5% since then. To be on pace, net emissions will need to drop 5.3% in 2020. And though the power sector is leading the charge, policy watchers caution accelerated action is still needed, particularly if electrification is to be part of the solution.

"Unfortunately a coal to gas switch is simply not going to be enough from a climate perspective," Union of Concerned Scientists Policy Director Rachel Cleetus told Utility Dive. "The surge to gas is a note of caution here."

The power sector's 2018 rise in emissions was in part due to a combined increase in electrification and a glut of natural gas additions meeting that growth, Ceres Senior Director of Electric Power Dan Bakal told Utility Dive, making the 2019 results a positive sign.

"If we continue on this trajectory of decarbonizing electricity, then the more we electrify, the more we can get emissions reductions from other sectors," he said. "At the same time, I would argue that there's a real awakening on the issue of climate and that's leading policymakers to take more action. And that can take the form of encouraging electrification."

Transportation emissions did decline slightly in 2019 — by 0.3% — while building emissions rose 2.2%, industrial emissions increased 0.6%, and emissions from other sectors rose by 4.4%, according to Rhodim's preliminary estimates.

The main discrepancy between the power sector and other major-emitting sectors is there are cost-effective, low carbon alternative technologies, such as wind, solar and natural gas, in electricity Senior Analyst and co-author of the Rhodium report Hannah Pitt told Utility Dive. There are also fewer players in the utility space, she said, which means a smaller pool to regulate.

"There are a limited set of utilities in any given power market, for instance," she said. By contrast, in the transportation and building sectors, "you are dealing with changing the behavior of millions of users or companies or households."