Two bipartisan bills signed by President Obama this month may open PJM to new generation from hydropower - a source many thought was fully exploited.

Integrating offshore wind into PJM will require billions in new transmission spending. Lines on shore also will have to be upgraded or built.

It isn’t only PJM’s Atlantic states that see promise in offshore wind. The Great Lakes also offer strong winds, along with their own unique challenges — winter ice, opposition from tourist towns, and in Pennsylvania, development restrictions put into law by casino opponents.