Innovation in energy technology has widespread implications for OECD economies. Although the energy sector accounts for a small share of GDP, the pervasive use of energy throughout modern economies makes uninterrupted supplies and stable prices critical to sustaining growth. Rapid growth in energy demand coupled with growing concerns about energy security and the environment, however, raise questions about the sustainability of the current energy system and call for renewed efforts to develop and deploy new and improved energy technologies that can support a sustainable energy system. Understanding how to stimulate innovation in energy technology is therefore of growing importance.