This is really relevant today, because at the moment we are trying to change our economy, and the way we do and make things, so that is not so dependent on fossil fuels. This won’t be easy – some people have said it’s a bit like when we got the first human on the moon. It’s a big scientific challenge for humankind to all face together.
So there are loads of scientists around the world looking at the ways we can make it happen. Some countries, like Sweden, have said they want to go fossil-fuel free within the next few decades, so soon we might start to see what a fossil-fuel free society looks like. We’re at a pretty exciting chapter in human history!
The best renewable energy sources to use depend on where you are in the world. For example, the UK is pretty good for wind power, especially offshore wind power, because we have so much coastline. But, unsurprisingly, we are not so great for solar power! (although we do have a bit).
The trouble with the renewable energy sources is that they vary a lot with the weather patterns etc. However, we need an energy system that is always available when we need it, and one that can react when demand increases (for example at half-time during a big football match when everyone gets up to put the kettle on). So really, what we need is a good system with a bit of everything in it, and smart ways of storing electricity and responding to demand.