According to a recent post on Renewable Energy World, the 31 states who have adopted renewable portfolio standards (RPS) will be a critical factor in the development of the nationwide renewable energy market.  The total installed capacity is projected to grow from 137 TWh in 2010 to 479 TWh in 2025, which is approximately 250%!  There are still challenges to overcome in many areas, including low power pricing and ambiguous federal policies, but these standards are a big step in the right direction.  A federal RPS would significantly enhance these projections and foster further growth.