No, the cheapest are renewables. Because say, pumping out solar cells by the billion is what mass manufacturing does best, and nuclear has nothing remotely comparable to that.

> If gas (as in fossil methane) is part of our long-term future, then we are quite screwed. Maybe it's viable with carbon sequestration, but that's unproven technology. The other options you listed will be required to make renewables 99.999% reliable.

You seem to be treating this as a moral issue. I see it as a practical one. Gas is just fine to fill whatever holes we might have. Yes, it's not clean. But using say, 10% fossil fuels rather than 60% would be a vast improvement. We can always improve further.