Studies point to the Middle East, Latin America, North America and Africa as the key regions for future oil plays

A study suggests that about 10 percent of the world's electricity could be produced by photovoltaic systems by 2020

The Saudis and OPEC have a vested interest in taking out higher-cost competitors who will certainly be hurt by the lower price

See where the United States falls on the list

The challenge of unseating the most polluting power source on the planet