Don't panic, but we will need to generate approximately 15TW of usable energy from renewable (carbon-neutral) sources by 2050 in order to stabilize the atmospheric CO2 concentration. And purely in terms of available energy, solar power has the greatest potential for meeting this requirement.
Solar is “probably the only long-term supply-side energy solution that is both large enough and acceptable enough to sustain the planet’s long term requirements,” according to Richard Perez, senior research associate at the Atmospheric Sciences Research Center at SUNY-Albany. Perez’ analysis includes geothermal, wind, all other significant renewable sources, nuclear fission, and all forms of fossil fuels.
So while wind, hydropower, and geothermal extraction may work well on a local or regional scale in certain areas, today the potential of solar exceeds any other renewable energy source by several orders of magnitude. It’s simply the only contender, besides nuclear power, for a global solution to supply civilization with the massive amount of energy it demands.
from The state of residential solar power