I truly enjoy people such as yourself: forward-looking, open-minded, creative folks who acknowledge what is but can see what could be.
Just this morning, I learned about a guy in Aspen, CO who is working on a new automotive design. The article just gave a short sketch, so I've put this on my to-do list for research and article-writing activities.
Thanks for bringing up tidal energy and desalination. If we look at the true sources of energy--wind, biomass, and petroleum all go back to the same place: the sun. Petroleum is a unique among these because geothermal energy is another fundamental, contributing energy source. Tidal is another unique one in that the moon's gravity becomes a fundamental energy source.
Desalination isn't an energy source but points to another crisis coming upon us, and that is water in the American West.
Hydrogen is certainly plentiful but locked into stable chemical bonds like H2O. Breaking these bonds to make straight hydrogen does indeed take more energy than what is yielded when H and O combust back to water. That's just the nature of physics; however, the same thing can be said about hydrocarbons.
The thing is, we don't create hydrocarbons for combustion; we mine them. Nature made them. So the part about using hydrogen in something like fuel cell technologies has a new twist to our use of energy--we will actually manufacture the fuel rather than mine it.
Where do we get the initial energy to manufacture the fuel? This energy must come from sources that already exist in the universe, right now, else we end up with a total net loss in the chemical bond transactions. In plain language, we can't burn coal, natural gas, or petroleum to make hydrogen fuel without coming full circle back to the problems we are trying to solve.
So, this leaves solar, geothermal, and gravity (tidal) sources. But here's a problem too: How can we collect enough solar, geothermal, and gravity energies to satisfy energy demands? Nature gradually collected solar and geothermal over millions of years to produce the hydrocarbons we now use. You can think of fossil fuels as representing highly concentrated energies. No direct conversion energy technologies we have today come even close to the amount of energy locked up in fossil fuel hydrocarbon chemical bonds. The indirect technologies (hydroelectric, make steam from geothermal to turn turbines) do come close. Tidal turbines might come close.
Well, for now we can try to spread out and diversify. GenX Futurist, you brought up feeding electricity back into the grid through individually-owned solar collectors. This has taken on some amount of momentum--some people around here are doing just that. I have even seen solar panel roofing shingles on the market (!). Death Valley could be set up with massive arrays of solar collectors that might rival Hoover Dam for megawatt output. The US has two coasts where tidal power could be harvested. We have several areas where geothermal is relatively easy to develop. The Midwest produces lots of biomass, as do our wildfire-prone Western forests.
I do believe this is eventually where humanity will go: spread out and diversify. The other part of this is to create more efficient devices that use the collected energy. We have the vision; now it is simply a matter of focus.
You and I share a critical time in history where humanity can choose to go one of two ways: cooperate and survive or continue ancient rivalries and die. Will the peacemakers find peace? Will the meek inherit the earth? The resistance to abandonment of fossil fuel energy sources is fierce. Yet, the rain and wind have flattened the Rocky Mountains--twice over. Perseverance will win in the end, IMO.