After completing training in 2013, Claire Kerstetter now works as a fluid technician on fracking jobs. Jeff Brady/NPR hide caption

itoggle caption Jeff Brady/NPR

PREPA's Central Palo Seco power station in San Juan, Puerto Rico. The utility's bondholders want to raise rates. That's a challenge when the median income is about half that of Mississippi, yet the U.S. territory's energy costs are among the highest in the nation. Alvin Baez-Hernandez/Reuters/Landov hide caption

itoggle caption Alvin Baez-Hernandez/Reuters/Landov

Oil pump jacks in Williston, N.D., in December. Oil prices have been on the rise, but some analysts say the global economic slowdown, fracking and the rise of alternative energy will mean less demand and lower prices. Eric Gay/AP hide caption

itoggle caption Eric Gay/AP

A photo released by Tesla shows its new Powerwall lithium-ion battery pack mounted on the wall (left) of a garage behind one of the company's electric cars. Tesla Energy hide caption

itoggle caption Tesla Energy

Austin Holland, research seismologist at the Oklahoma Geological Survey, gestures to a chart of Oklahoma earthquakes in June 2014 as he talks about recent earthquake activity at his offices at the University of Oklahoma in Norman, Okla. The state had three times as many earthquakes as California last year. Sue Ogrocki/AP hide caption

itoggle caption Sue Ogrocki/AP