Forbes: The “cubic mile of oil”–a metric roughly equivalent to the amount of oil consumed worldwide each year–is frequently used to explain the challenge facing solar, wind, geothermal and biomass power. So, what would it take to replace the amount of energy in a cubic mile of oil Roughly 4.2 billion wind turbines, 91.2 solar panels, 2,500 nuclear power plants or 200 Three Gorges Dams, according to Menlo Park, Calif., nonprofit research institute SRI International. In other words, …