Deep reductions in CO2 emissions from the global energy system are technically feasible over the course of the next century, using various combinations of low CO2 energy technologies, Moreover, an energy future characterized by deep emissions reduction over the longer term is plausibly achievable with costs for energy services that are approximately the same as estimated future costs of energy services based on conventional energy - given adequate time (several decades) and an economic and political climate conducive to the needed innovations, Strong and sustained investments would be needed for research and development, demonstration and diffusion of a wide range of energy technologies characterized by low or zero CO2 emissions, Since at present the levels of investment are low and declining, new public and private sector energy innovation policies are needed.