There are lots of ideas, like using a reverse cyclotron (a particle decelerator) to drive a turbine, or harnessing the photo-electric effect (essentially solar

There are lots of ideas, like using a reverse cyclotron (a particle decelerator) to drive a turbine, or harnessing the photo-electric effect (essentially solar panels, but for x-rays). https://en.wikipedia.org/wiki/Direct_energy_conversion https://en.wikipedia.org/wiki/Direct_energy_conversion