"A gas-fired plant was
about 42% efficient. And in natural gas combined-cycle power plants—in which waste heat from a natural gas turbine is used to power a steam turbine—generation may be as much as 60% efficient."
Want to understand the basics of America's current energy situation? The National Academies, advisers to the nation on science, engineering, and medicine, provides objective information about the United States' current energy sources and uses, as well as a look forward to the future of energy.
needtoknow.nas.edu
Nothing achieves 100% efficiency. And natural gas requires pipelines, and wells, as well as fracking. Solar requires panels and a grid. And it is very scalable. And once the panels are installed, the energy is free.