It is not a secret that all forms of energy that we know and use is a direct or indirect derivative of the Sun's immense and never ending energy. Even fossil fuels such as coal, gas & petroleum is indirect result of Solar energy, and even including the food we eat comes out of the Solar energy.

So it makes all sense to make use of this wonderful free energy for powering ourselves and our needs.

In this picture, all the circles outside the 'Large Yellow circle' is the finite & single use resources available to us, which is not going to regenerate back in the next million years. However all the energy circles inside the Yellow Circle (which happens to be the Sun's energy) is the resources that is available annually, year after year.