(b) setting up the infrastructure to produce clean energy is not purely clean itself.
Until you can account for every last gram of toxic solvent, mine tailings, electricity consumed during manufacture, and CO2 produced during transport from e.g. solar panels, it's not entirely clean. It's just better than the alternative. Not using the energy is always cleaner.
That idea really excites me! If our energy sources are both clean and abundant, that opens up a lot of doors to technology that previously had uncomfortable tradeoffs. For example, high-energy-consumption recycling instead of mining new raw materials; right now it can be a bit of a wash (sure, we're mining less, but we're burning coal to power the process), but post-scarce-clean-energy it becomes way less of concern. Likewise with a lot of automation tasks. Very exciting!