If you want nuclear as part of the solution, you necessarily need to explain why renewable energy won’t be able to do the job alone. This particular open letter says:
Renewables like wind and solar and biomass will certainly play roles in a future energy economy, but those energy sources cannot scale up fast enough to deliver cheap and reliable power at the scale the global economy requires.
We’ll have to wait a couple of decades to see if solar and wind are able to provide for 100 percent of energy. Contrary to what Jim Hansen (not an expert on energy systems) thinks, I expect that this will happen. But we already know one thing for sure.
Solar and wind have scaled up enough already to make nuclear lose in the market place. Even with nuclear enjoying the benefit of insufficient levels of insurance (leaving the remaining risk for the taxpayer), it just doesn’t make economic sense any more to build new nuclear plants.
And if you decide to build a new nuclear plant today, it won’t be able to deliver energy until ten years later, and will then have to compete for a couple of decades against wind and solar at the much more reduced prices these technologies will have then.
In contrast, you can build a large solar project in a couple of weeks or months. I am not sure why that is “not fast enough”, but it is sure faster than nuclear by a factor of over ten.
More here: Jim Hansen and the Easter Bunny