Once we break out of our circular argument (Sustainable energy only accounts for X%, and therefore can’t meet demand) and start to look at costs beyond the initial investment, it makes more sense to use wind, solar, and tidal energy (where the “resource” is near infinite, abundant and free) then anything else.
Where we need to start researching and investing is in transportation and storage of energy. We already know how to make power, now we need to learn how to move it efficiently.
Here in America, there’s enough wind power in the Dakotas to power all of the US, and enough solar power in the south west to do the same. On the world stage, Africa could theoretically power most of the world using solar power. The catch is transferring that power to the rest of the world.