by Michael Sivak, Sivak Applied Research.
Battery electric vehicles are only as clean as the energy source used to generate the electricity that powers them. The calculated relative amounts of well-to-wheels emissions of greenhouse gases from eight different energy sources are shown in the table below. (The calculations were based on the data developed by the Union of Concerned Scientists.) These results indicate that coal and oil are the energy sources leading to most emissions, and that hydro, wind, and nuclear are the energy sources leading to least emissions. On the two extremes, coal and oil result in about 176 times the emissions from hydro.
This brief study analyzes, for each individual state, the changes from 2008 to 2018 in the use of coal (one of the two most polluting energy sources) to generate electricity. (Oil is used relatively infrequently in the United States as an energy source for electricity. In 2018, only two states used oil to generate more than 3% of the electricity: 68% in Hawaii and 12% in Alaska.) The raw data (the percentages of electricity generated from different energy sources in the individual states) came from the Nuclear Energy Institute.
The results indicate that the percentage of electricity generated from coal decreased from 2008 to 2018 in 49 states. The largest decreases (in terms of percentage of percentage) were in Massachusetts (from 25% to 0%), Connecticut and New York (both from 14% to 1%), and Delaware (from 70% to 5%). The increases occurred only in Alaska (from 9% to 11%) and in Wyoming (from 94% to 96%). For the United States overall, the use of coal to generate electricity decreased from 49% to 28%.
The table below shows the top 10 states in terms of the percentage of electricity generated from coal in 2008 and in 2018.
The number of states that generated at least 75% of electricity from coal decreased from 9 in 2008 to 3 in 2018. Analogously, the number of states that generated at least 90% of electricity from coal decreased from 5 in 2008 to 2 in 2018.
Michael Sivak is the managing director of Sivak Applied Research and the former director of Sustainable Worldwide Transportation at the University of Michigan.