Actual carbon energy is the least harmful to the environment, which is why nature evolved to use carbon to store energy rather than other mechanisms. Your body operates on carbon fuel.

The problem is man has mastered getting the energy out of carbon fueled, but still has to master the art of creating carbon fuel.

Which is why if you read my links, you will see that the technology is underway under which we would simply produce our own carbon fuel using CO2 in the air resulting in net zero emissions. Unlike attempting to replace carbon fuel which will never be practical and creates its own source of "waste" (used up batteries, solar panel, wind blades, nuclear waste, etc), the ultimate end game will be to simply mimic nature to store energy using CO2, water, sunlight, and a catalyst and then consume it as needed, being sure to leave enough CO2 to support adequate plant growth.