Technology can make a significant contribution to reducing greenhouse gas emissions from the energy sector. But it can only do so if efforts to develop and deploy advanced energy technologies are redoubled and if technological advances are combined with measures that discourage the emitting of carbon by making it more expensive. Efforts with a near-term focus are needed, but so is work that will only bear fruit years from today. Both are vital. Both must start now and continue over time. Government and industry both have indispensable roles in the task of maximising energy technology’s contribution to emissions reduction. This report is a call to action to IEA Member countries to find ways, compatible with their own circumstances, to achieve that end. It reviews a large number of technologies that could prove important in reducing energy-related emissions in both the near and long term. It points out how the availability of advanced energy technology can mitigate the cost of emissions reduction, and it outlines how traditional “barriers” to using new technology can be overcome. It deals directly with the issue of what governments can do in this area and points out where government action is needed. The report builds on two previous IEA reports – Energy Technologies for the 21st Century and IEA/OECD Scoping Study: Energy and Environmental Technologies to Respond to Global Climate Change Concerns.