Is simple! A working steam engine does Molecular Nuclear Fusion
This will give scientists 560 years of research.
My favorite sort is plasma Molecular Nuclear Fusion. A50x1cm steam plasma tube at 4 atmospheres produces a constant 1.2MW, from 10-17cc of regular water a DECADE. No CO2. No radioactive waste. No Fossil Fuels burn.
I told the department of engineering materials this in March 2001.