The United States shares with many other countries the objective of stabilising greenhouse gas (GHG) concentrations in the Earth's atmosphere at a level that would prevent dangerous interference with the climate system. Many believe that accelerating the pace of technology improvement and deployment could significantly reduce the cost of achieving this goal. The critical role of new technologies is underscored by the fact that most anthropogenic greenhouse gases emitted over the next century will come from equipment and infrastructure built in the future. As a result, new technologies and energy sources have the potential to transform the nation's energy system while meeting climate change as well as energy security and other important goals. This book identifies and describes the barriers impeding the commercialisation and deployment of climate change mitigation technologies.