Biofuels are not as green as they appear.  You have to clear and cultivate the land on which to grow the plants that produce them.  That means an end to wilderness, to nature preserves.

For example, take Brazil. Greens all over the world praise it for meeting its fuel needs by biologically grown alcohol.  Very few notice the destruction it wreaks on the Amazonian rain forest, as the timber is burned, and land is cleared for expanding sugar cane plantations.

The greenest of all energy sources is nuclear energy.  When properly generated, it emits nothing to the atmospere, it destroys uranium, the source of radon gas that pollutes the air, and the solid wastes it produces would not fill the Cheops Pyramid for hundreds of years.

Solar and wind energy have their advantages, but also their drawbacks.  The sun doesn’t shine intesely enough in most of the land.  Solar panels would shade the surface, making plant growth problematical.  Wind is capricious, and not intese enough in most places to repay the investment. Consequently, we are stuck with nuclear energy for the foreseeable future.

P.S. Fusion energy is also nuclear energy, generating radioactive waste, so don’t bank on it!