Aliso Canyon cf Vermont Yankee
Comparison of the Aliso Canyon blowout with the closure of Vermont Yankee
On 25 Feb 2016 a post on facebook compared the CO2 equivalent of the Aliso Canyon methane gas leak with the amount of CO2 emitted by the natural gas plants replacing power from the Vermont Yankee Nuclear Power plant after it closed at the end of 2014.
In a paper in Science Dr. Stephen Conley and others calculate that the Aliso Canyon blowout resulted in 97,100 tonnes of methane entering the atmosphere, equivalent to 2.4 million tonnes of carbon dioxide.
According to Wikipedia the Vermont Yankee nuclear power plant produced 4,703 GWh annually.
From Wikipedia nuclear power produces 12g of CO2 per kWh whilst CCGT produces 490g.
Thus Vermont Yankee produced 4703*1000000*12/1000000 = 56,436 tonnes of CO2 per year whilst the CCGT stations replacing it will produce 4703*1000000*490/1000000 = 2,304,470 tonnes of CO2 per year, an extra (2,304,470 - 56,436) = 2,248,034 tonnes of CO2 per year.
Therefore the closure of Vermont Yankee is equivalent to an Aliso Canyon leak every year.