Today, another profound transformation is underway. A combination of forces is taking us from a carbon-centric, inefficient energy system to one that emphasizes efficiency and draws from diverse energy sources-including the sun. In 2012, more than half of total net additions to global electric generating capacity came from renewable sources. Since 2008, U.S. electricity generation from wind and solar power has more than doubled. Sharp and largely unforeseen growth in the U.S. shale gas market has altered the dynamics of the global energy landscape and helped spark a renaissance in U.S. manufacturing. These changes, together with improvements in energy efficiency and a changing transportation sector, have contributed to a drop in U.S. carbon emissions, which hit a 20-year low in 2012. At the same time, the business of energy is changing from one focused on kilowatt hours to one focused on services. The roles that distribution and transmission play could change dramatically as we move toward an energy system that is more diverse, more dispersed, and more carbon neutral. Energy is becoming a more essential component of strategies to safeguard and improve our security, economy, and environment. As the U.S. Energy Department's only national laboratory focused on renewable energy and energy efficiency, the National Renewable Energy Laboratory (NREL) is uniquely positioned to help inform and guide energy system transformation. NREL complements its scientific research with high- quality, credible, technology-neutral, and objective analysis that spans the entire energy portfolio to inform policy and investment decisions as renewable energy and energy efficiency technologies move from concept to commercialization to market penetration. For 35 years, our work with the public and private sectors has catalyzed the emergence of a clean energy industry that is creating jobs and providing viable, low-carbon energy options at home and around the world.