America is in the midst of an energy revolution. Over the last decade, the United States has slashed net petroleum imports, dramatically increased shale gas production, scaled up wind and solar power, and cut the growth in electricity consumption to nearly zero through widespread efficiency measures. Emerging advanced energy technologies provide a rich set of options to address our energy challenges, but their largescale deployment requires continued improvements in cost and performance. Technology is helping to drive this revolution, enabled by years to decades of research and development (R&D) that underpin these advances in the energy system. //

The 2015 Quadrennial Technology Review (QTR) examines the status of the science and technology that are the foundation of our energy system, together with the research, development, demonstration, and deployment (RDD&D) opportunities to advance them. It focuses primarily on technologies with commercialization potential in the midterm and beyond. It frames various trade-offs that all energy technologies must balance across such dimensions as cost, security and reliability of supply, diversity, environmental impacts, land use, and materials use. Additionally, it provides data and analysis on RDD&D pathways to assist decision makers as they set priorities, within budget constraints, to develop more secure, affordable, and sustainable energy services.