Discuss potential of solar energy. Why have we not been able to make better use of that potential? ...

The potential of solar energy is tremendous. The solar energy reaching the Earth's surface on any given day is about
100,000 times greater than all the electric power capacity of the world.

Mostly it is used as an additive to gasoline to produce gasohol.
 The carbon dioxide produced can be used for the carbonation of beverages, for drying grain, in fertilizer production,
in fire extinguishers, in refrigeration systems, and in dry-ice manufacturing. The residue from the
alcohol can be used as feed for livestock.

The U.S. ethanol production averaged 900,000 barrels per day for the first half of 2012. That would have resulted
in about 13.8 billion gallons of ethanol production on an annual basis.