The following calculation shows how much effect Ohio’s nuclear plants have on reducing CO2 emissions. The data are for 2016, the latest year for which Ohio’s emissions are available.
We see what happens if the plants are shut down, and their electricity is replaced by electricity generated using fossil fuels.
The Appendix shows how many tons of CO2 are produced in Ohio for each MWh of electricity. The answer is 0.68. If the nuclear plants were shut down and their 18.3 million MWh electricity now came from fossil fuels, the increase in CO2 = 0.68*18.3*106 = 12.4 Million metric tons. Ohio emitted a total of 206.3 metric tons of CO2 from all sources in 2016 (2). The resulting percent change in CO2 level = +12.8/206.3 = + 5.7 %
Apppendix
Ohio produced 118.9 million MWh of electricity (1), while electric plants generated 80.6 million metric tons of CO2 (2). Dividing 80.6/118.2 = 0.68 tons CO2 per MWh.
References
(1)Energy Information Administration, Electricity Data Browser, https://www.eia.gov/electricity/data/browser/
(2) EIA State Carbon Dioxide Emissions Data, https://www.eia.gov/environment/emissions/state/
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