What might replace fossil fuels in the future?
This is a question that scientists and engineers are thinking a lot about and are undecided.
Fossil fuels provide the majority of the planet's energy, thus it is going to take a lot work to replace fossil fuels with more environmentally friendly energy sources.
It will likely take a combination of these technologies to replace fossil fuels, and different areas will likely use different combinations. It's also worth considering that, as more people use these technologies, more money will be invested in them, and more research can be done on improving these technologies even further.
Some countries are choosing to invest their time and money into renewable energy sources:
Reducing our energy use overall though would help us rely on renewable energy. We can do this by creating better public transportation, eating foods that are local and in season, creating usable bike lanes in cities, using less energy at home and using energy efficient appliances, and so forth.
To read more about what is possible when it comes to renewable energy, check out this article.