What alternatives are there to fossil fuels?

Any of the other types of fuel! This includes nuclear energy (fission, and once we manage to do that, fusion), wind energy, hydraulic (water) energy, solar energy, geothermal energy, and many others.
There is a source of energy that is more friendly to the environment that has not been looked into yet such as using the force from the waves to power everything that fossil fuels are being used currently to power and you could use wind power as well to make a better alternative to fossil fuels