|A solar garden|
Of course the wind doesn't always blow, or the sun shine. The more we come to depend on intermittent power sources like these, the more we will also need to store power for later use (if part of the time we can generate a surplus). Logical sites for solar farms (deserts) and wind farms (on open plains and high hills; off the coasts) may be remote from where power is needed -- say, Minneapolis in the winter. Read the preceding as: lots of new infrastructure (with attendant costs) for power generation, power storage, and long-range power distribution. A more subtle point is that a power grid reliant upon many intermittent supplies will also need improvements to maintain stability while generators and storage sites ramp up and down, come on and offline.
And land ... lots of land. Energy sprawl, some call it. Wind and sunlight are diffuse sources of energy.
|Upon due reflection ...|
|Beam it down, Scotty|
To summarize: more energy input than ground-based solar, virtually all the time (the exceptions known in advance with astronomical precision), with the resulting power delivered close to where it's wanted.
So what's the catch?
Upfront costs. Putting stuff into space is pricey. The coming age of commercialized near-Earth space operations (Go, SpaceX! Go, Dragon!) will surely reduce launch costs somewhat, but lofting entire power plants will never be cheap. The answer -- and a premise of my upcoming novel Energized -- is capturing an asteroid into Earth orbit, and building Up There with those materials.
With Planetary Resources newly announced (and backed by billionaires), maybe mega-resources will be available in Earth orbit sooner rather than later.