No, we don't. We can also keep digging for limited stuff and use that for cheap energy temporarily, while technology advances and other sources become much chea

No, we don't. We can also keep digging for limited stuff and use that for cheap energy temporarily, while technology advances and other sources become much cheaper even without research specifically directed at that. That's how today's society developed, except with the side effect that we've also released a large amount of CO2 into the atmosphere.