New energy technologies in the U.S. made further critical advances and locked in long-term gains in 2015, according to a new study from Bloomberg New Energy Finance (BNEF) and the Business Council for Sustainable Energy (BCSE). Among other achievements, energy efficiency continued to rise, renewable power generation set new records and natural gas consumption and production surged as CO2 emissions fell to levels not seen since the 1990s, while power prices remained flat.