Wednesday was an exciting day in the world of U.S. electricity emissions. Why you might ask? The Environmental Protection Agency (EPA) released the 2018 installment of the Emissions and Generation Resource Integrated Database, or eGRID for short. This data set allows the public to review the most the most recent emissions data from electric power generation across the United States.
The eGRID 2018 data includes a number of important figures for the power sector, including air emissions for numerous pollutants (i.e. nitrogen oxides, sulfur dioxide, carbon dioxide, methane, and nitrous oxide), emission rates, net generation, and resource mix.
What’s especially exciting is that we can now compare the 2018 data to eGRID’s historical figures that date back to 1996. Let’s look at a few key areas.
In 2018, the U.S. electric power sector generated 4,168 terrawatt-hours (TWh) of electricity, or a whopping 4,168,370,117,666 kilowatt-hours (kWh) of power generated. Compared to 1996, total net generation increased 35 percent from 3,087 to 4,168 TWh.
To put things into a more comprehendible amount, this translates to 12,741 kWh of electricity generation on a per capita basis in 2018. Figure 1 (below) shows this data for each state. Some of these states have especially high rates due to electricity exports and electricity production for industrial processes.
Tip: slide your cursor or finger over the chart to see state-level data!
Unfortunately, all those kilowatt-hours come at an environmental cost in terms of emissions. The production of those 4,168 TWh of electricity emitted 1.97 gigatons of carbon dioxide in 2018. That equates to a carbon dioxide emissions rate of 947 pounds per megawatt-hour (lbs/MWh).
These figures are much improved since 1996, when eGRID started releasing data. The U.S. average CO2 emissions rate fell 36 percent from 1,485 lbs/MWh to 947 lbs/MWh and total carbon emissions from electricity generation decreased from 2.29 to 1.97 gigatons.
Despite consuming a lot more electricity, the U.S. is emitting less carbon dioxide into the atmosphere from the power sector than it did back in 1996.
While it’s helpful to review carbon emissions at the national level, electricity policy is mostly decided at the state level. Some states, like Delaware, have significantly reduced their carbon emissions over the last 22 years while others, like Maine, have shown increases. Each state really demands further analysis to understand why these changes have occurred.
Figure 2 (above) shows total carbon dioxide emissions by state at 1996 and 2018 levels. Figure 3 (below) shows the net change over the past 22 years, ordered by states that have had the largest impact on carbon reductions to the least impact (or carbon increases).
The big contributors to carbon emissions reductions are easy to see in Figure 3. The five top “reducers” since 1996 – Ohio, Indiana, Tennessee, Pennsylvania, and Kentucky – account for 59 percent of the net reductions of the U.S. as a whole.
The reason for these reductions is in large part due to the retirement of many coal-fired power plants across the United States.
The 2018 eGRID plant database included 408 coal-fired plants, representing 1.3 gigatons of emissions, while the 1996 eGRID power plant database included 454 coal-fired power plants, representing 2.0 gigatons of emissions. Much of this coal capacity has been replaced by natural gas-fired units, but also renewable energy like solar and wind.
While the change in total carbon emissions output is no doubt important, it is also helpful to compare the carbon emissions rates across states. Several small states - including Connecticut, Delaware, New Hampshire, and New Jersey - may not emit nearly as much on absolute terms, but they have made significant improvements over the past two decades to "clean" their power generation.
Figure 4 demonstrates how the vast majority of states have significantly reduced their carbon dioxide emissions rate. Nevada reduced its CO2 emissions by a whopping 72 percent from 2,700 to 745 lbs/MWh.
It's important to note that the carbon dioxide emissions that are included in this analysis account for about a third of U.S. energy-related carbon emissions (5.3 gigatons). The remaining two-thirds of carbon emissions are attributed to transportation and the burning of fossil fuels like natural gas for heat and industrial processes.
Other emitters, like forestry and agriculture, add even more carbon emissions beyond this energy-related figure. In 2017, total U.S. greenhouse gas emissions in carbon dioxide equivalent stood at 6.5 gigatons with 27 percent attributable to electricity production. Overall, U.S. greenhouse gas emissions had decreased by 0.5 percent from 2016 to 2017.
There is a wealth of data in the eGRID tables. What else would you like to see? Feel free to send me a recommendation for a future chart or analysis at email@example.com.
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