Seems to me that the way we currently transform different types of energy into electricity are pretty archaic, basic and simple. We can pretty much instantly transform mechanical and kinetic energy into electricity, and after the advent of photo voltaic cells, you can pretty much directly convert light into electricity. These are fine for mechanical, kinetic, and light forms of energy, but collecting energy for use as electricity from other forms are currently less efficient.
For instance, as far as nuclear and heat... we have to first convert it into mechanical or kinetic energies before we convert it to electricity.
As far as nuclear, we only use the heat generated to make steam to mechanically turn a turbine.
As for heat, again, it is used to first boil water, which loses energy, then the steam produced spins a turbine, again losing energy in the process.
Just seems very inefficient to me, with the exception of photo voltaic cells converting light, we seem to first try to convert to mechanical or kinetic energy before we convert to electricity.