Balancing energy requirements for continued social and economic progress against the potential resulting environmental and socio-political impacts is widely acknowledged to be a significant global challenge in the 21st century. By 2050, global electricity demand is expected to have increased by about a factor of 2.5. In 2006, nuclear energy supplied 2.6 billion MWh: 16% of the world's electricity and 23% of electricity in OECD countries. Nuclear energy could play a significant role in avoiding CO2 emissions, providing greater energy security and reducing the serious health effects that result from fossil fuel combustion. The delay and failure thus far of some major disposal programmes for highlevel radioactive waste continue to have a significant negative impact on the image of nuclear energy; governments and the nuclear industry must work together to deliver safe disposal.