Access to affordable, modern energy services is a prerequisite for the achievement of sustainable development and the Millennium Development Goals. New and renewable sources of energy can play a crucial role in providing needed energy access, supporting and accelerating economic and social development, creating employment opportunities, reducing greenhouse gas emissions and ensuring energy security. Rising global energy demand requires greater energy diversification and an increase in the share of new and renewable energy in the future global energy supply. The current share of renewable energy in the global energy supply is still low, however, in spite of its vast potential, because of the high costs of many renewable energy technologies. It is therefore of utmost importance to increase the cost-competitiveness of renewable energy technologies by adopting and implementing policies that ensure research, development, deployment and transfer of those technologies, especially to developing countries. Policies can stimulate the required public and private investment at the local, national and international levels and encourage public-private partnerships and international cooperation.