I know that this essay is likely not to be popular with progressive folks, but I am not only a progressive, I am a scientist as well. In my opinion, the only relatively clean option for power that we have, other than natural gas (which is less plentiful and not as clean as the TeeVee adverts say) is the fission of uranium and plutonium.
I realize that this sounds pretty bold, but please bear with me whilst I build my case. We need power in the meantime for the transition between fossil fuels and truly sustainable ones, and nuclear power is the only one that can provide that power. First the physics, then the economics, and then the future.
Nuclear power is just electricity, except for some very exotic heat engines on deep space vessels. Beyond the orbit of Mars, the sunlight is too feeble to power photovoltaic cells, so nuclear energy is necessary. That is provided by plutonium-238, which decays mostly by alpha emission to make lots of heat when it hits a metal shield around the thermocouples that convert the heat into electricity. This is not a very efficient process, but is good for deep space.
Here at home, uranium-235 and plutonium-239 can be used to produce electricity by heating water to the boil, and far beyond.