Conventional wisdom in many reasonable clean energy scenarios have Bill Gates' "Next Generation" (the other respondent's TerraPower/Gen IV) being a great "transitional" clean energy source for maybe the next 75 years. Reasons being:

1) Sodium core not as volatile

2) Doesn't use weapon grade material

3) Transitional since wind/solar held back by intermittency/lack of storage/slow to scale up.

4) Can be used to produce cheap hydrogen (a portable power source w relatively high energy density to replace gasoline/diesel in high torque apps)

5) Nuclear power has a bad reputation and is expensive and slow to bring online. Yet Gates believes Next Gen is best way to address climate change.

Biden infrastructure bill includes money for nuclear, note that green Germany is back to relying on nuke plants, lesser of the evils?