You're right that people have been thinking about and working on renewable energy for a long time. However what's only become true very recently is that it's cheaper to generate energy using renewable sources than to use fossil fuels. That's a massive milestone because when a new power source is built it will more likely than not be renewable.
People making sacrifices is important, but what if you weren't only giving people the opportunity to help the environment, but also to improve their bottom line? Makes the pitch a lot easier and helps us to build momentum in the right direction.