Renewables don't need to fulfill everything all the time. If they need assistance from fossil fuels 10% of the time, that's a 90% cut in greenhouse gas emissions. The last 10% won't be the biggest issue to deal with.
So you can build expensive nuclear plants for that small fraction of the time, or you can continue to use existing fossil fuel plants for free. The difference to the carbon bottom line is small.
Renewables don't need to fulfill everything all the time. If they need assistance from fossil fuels 10% of the time, that's a 90% cut in greenhouse gas emissions. The last 10% won't be the biggest issue to deal with.
So you can build expensive nuclear plants for that small fraction of the time, or you can continue to use existing fossil fuel plants for free. The difference to the carbon bottom line is small.