While there are great sources of energy that humanity has not yet discovered, humanity is a long way from discovering them, and it will have to survive the Great Waves of change even to have a chance of discovering them.
The transition period to a new stability in the world will be long and very difficult. Making this transition is not impossible. In fact, it must happen. But do not think that it will happen in and of itself. Do not think that technology alone will make it possible.
The human population will have to become much smaller in the future, hopefully by humane will and through compassionate means. If not, then nature will devastate the human population through deprivation, conflict and war.
You will have a smaller world to live in. Perhaps only a billion people could live here, maybe two, but not much more. That would require advanced technology, your best efforts, a strong international community, tremendous cooperation and the prevention of conflict and war. If everything is done well and correctly, with immense human contribution, you will still have to have a small world population to achieve stability.
If these actions are not taken, if humanity will not and cannot prepare, if it cannot restrain its own greed, corruption and competition with one another, then the results will be far worse, so much worse that words cannot describe it—a collapse of civilization, an immense reduction in the human population further devastating the world and depleting its resources.
From The Great Waves of Change, Chapter 9: The Great Waves Prophecy