BE.... green energy can be actually much muuuuuch cheaper than fossil fuel... in fact fossil fuel prices will continue increasing.. it is a limited non-renewable resource... hence the less is left... and the more the demand ... the more expensive it will become.. it is a simple economics.

The green energy and in particular renewables with high coefficients can be very cheap... just harvesting of sun energy alone could bring the prices down and secure human civilization for many centuries.

If you always thing short term... then you get yourself into mess... if you do proper planning and evolve.. like an intelligent civilization should do... then you make life good for everyone