Yes of course. Perhaps one of the, as yet , least exploited is tidal power. The Moon isn't going anywhere just yet and so the tides will stay on time. If the turbines were rigged so that they could produce energy from the tide going out, as well as it coming in, it would give a continuous source of energy, even solar only works in daylight and there has to be a breeze for wind energy. Any coastal zone has tides and if they have any kind of a river inlet, then all the better. The question is not, are there sources of energy, there are; but which can be developed whilst still keeping the current rich, rich. It is not the means that is lacking but the willingness to change.