Isn't the math on solar really simple? (1) Annual amount of energy the sun generates on the surface of the earth minus (2) the annual amount used by non-human forms of life and natural processes equals (3) annual human energy balance. Now, maximize capture of (1) while minimizing externalities of such capture. How is anything other than direct solar-to-electricity conversion on the table long-term? Presumably even wind energy production relies on surface temperature differentials stored over periods longer than the consumption period in question--meaning, there's a resource being depleted.