Coal and the like is finite and will run out. We'll have to switch to renewable energy eventually - the question is how much we'll damage our planet before we do.
We would really have to invest on renewable energy as that would be the only way to sustain us in the long run. Earth is being destroyed bit by bit whether we admit it or not. Climate change, and visually we can see the damage that is being inflicted on this planet. With renewable energy we can keep the damage to a kinimum we can maintain our life and we would be making the world a better place.