Think of it this way: the boiling water and spinning turbine part is the easy bit. All the hard engineering and tradeoffs in thermal/mechanical power generatio

Think of it this way: the boiling water and spinning turbine part is the easy bit. All the hard engineering and tradeoffs in thermal/mechanical power generation, be it coal, natural gas, biofuels, hydro, or nuclear, are in dealing with the fuel/moving mass. Enormous amounts of engineering go into finding coal, digging it out of the ground, and dealing with the resulting combustion gasses and ash. The boilers and turbines - while impressive - are just one small part of that effort. Natural gas is no different: the turbines are pretty simple compared to the huge effort that goes into getting it out of the ground. Hydroelectricity again uses turbines. And again, they're relatively trivial devices compared to the huge engineering challenges of building and maintaining the dams themselves. Not to mention the complex tradeoffs around when and where to use them. If reliable high-energy motion really was everywhere, yes, this would be easy. But that simply isn't the case. The closest we have to that is hydroelectricity, and in most countries dams have already been built on most of the available sites.