Report: In 2017, Zero-Carbon Resources Accounted for More Electricity Generation Than Gas or Coal

The US power sector continues transitioning away from coal and toward zero-carbon energy resources, as the largest electricity producers continue to reduce air pollutant emissions and their corresponding contributions to climate change, according to recent analysis.

"Benchmarking Air Emissions of the 100 Largest Electric Power Producers in the United States" examines and compares key air pollutant emissions of nitrogen oxides, sulfur dioxide, carbon dioxide, and mercury from the 100 largest US power producers, highlighting environmental performance and progress across the sector.

The report found that in 2017, for the first year ever, zero-carbon resources accounted for more electricity generation (35.4%) than either gas (32.1%) or coal (29.8%).

The chief difference in 2017 was the steadily rising amount of power produced in the US from renewable wind and solar resources. In 2016, renewables, which include wind, solar, geothermal and biomass, delivered 6.9% of US energy; in 2017 that amount rose to 8%. Nuclear led all zero-carbon resources in 2017, generating 56.3% of non-emitting power, followed by 22.6% from renewables and 21.1% from hydro.

Despite a decrease in coal generation, carbon emissions from the electric power sector increased modestly in 2018 (1% increase); this is a departure from the prior years. Electric sector NOx and SO2 emissions declined modestly in 2018 (3.7 and 5.5%, respectively) over the previous year.

The new analysis points to a continued decoupling of economic growth and carbon emissions, as well as to the efficacy of policy solutions in helping the US power sector reduce emissions of sulfur dioxide and nitrogen oxides, which cause acid rain and smog. It identifies potential first steps towards deep decarbonization pathways for the US power sector. Such steps would aim to significantly reduce carbon emissions by 2050 -- consistent with the goal called for in a 2018 Intergovernmental Panel on Climate Change (IPCC) special report to hold global temperature rise to well-below 2 degrees Celsius in order to avoid serious impacts from climate change.

Other major findings include:

•  Power plant sulfur dioxides and nitrogen oxides have decreased 92% and 84%, respectively, since Congress passed major amendments to the Clean Air Act in 1990.
•  Mercury air emissions from power plants have decreased 90% since 2000, as first-ever federal limits on mercury and other hazardous air pollutants from coal-fired power plants went into effect in 2015.
•  Despite a 1% increase in carbon dioxide (CO2) emissions between 2017 and 2018, carbon emissions from the US power sector have decreased 20% since their peak in 2005, while gross domestic product (GDP) grew 41% -- signaling that carbon emissions reductions and economic growth can go hand in hand.
•  In 2017, the nation’s largest power producers, together, released 1.16 million tons of sulfur dioxides, 0.90 million tons of nitrogen oxides and 1.64 billion tons of carbon dioxide.
•  US power producers have a wide variability of carbon emission rates, with 5 of the 20 largest generators emitting more than 1,500 lbs/MWh and 5 emitting less than 650 lbs/MWh.
•  Since 2005, generation from renewables has doubled, occupying a 9% share of the US total in 2018, due in part to the fact that 29 states, Washington, D.C., and three territories have adopted renewable portfolio standards, and eight states and one territory have set renewable energy goals.

The latest Benchmarking Air Emissions analysis is the 15th such report released since 1997. The benchmarking analysis is a collaborative effort between Ceres; Bank of America; power producers Entergy and Exelon; and the Natural Resources Defense Council (NRDC). It is authored by M. J. Bradley & Associates.

The analysis is based on publicly reported generation and emissions data from the US Energy Information Administration (EIA) and the US Environmental Protection Agency (EPA). It also provides detailed fuel mix information for all of the producers -- including their share of fossil fuel, nuclear, natural gas, and renewable sources used to generate electricity.