 Energy is the engine of economic development and prosperity. Growing populations and expanding industries need more and more of it. But can energy power modern economies without heating the planet or polluting our air? Each nation has to choose which types of energy to use depending on its natural resources, industry, agriculture and lifestyles. Nuclear power is one option. It currently produces about 11% of the world's electricity while releasing almost no greenhouse gases or air pollutants. About 450 nuclear power reactors operate in 30 countries. Another 60 or so reactors are under construction, mostly in Asia. About 30 other countries are considering introducing nuclear power. A nuclear power plant uses uranium as fuel. Fuel pellets are combined into large fuel assemblies and placed inside a reactor core. In the reactor the uranium atoms split. This releases energy used to boil water and produce high pressure steam. The steam turns a turbine connected to a generator which produces electricity. Nuclear power can help provide reliable amounts of base load electricity. It can reduce a country's dependence on imported fuel. And it's a low carbon energy option. Today most electricity generation is dependent on fossil fuels. When burned to produce electricity they pollute the air and release greenhouse gases such as CO2. Nuclear power by contrast produces one third of the world's low carbon electricity. Its CO2 emissions are extremely low comparable to hydro or wind power. Nuclear power is not without its challenges. The costs of construction are high. But once built plants are relatively inexpensive to operate and can provide a steady supply of electricity for decades. Like most forms of electricity generation nuclear power produces waste. Methods for disposing of waste with low levels of radioactivity are well established. Highly radioactive waste such as spent nuclear fuel removed from reactors may be reprocessed to use again as fuel. Or eventually it will be permanently placed in repositories deep underground isolated from people and the environment. Every country that uses nuclear technology has a responsibility to do so safely and securely. Following the 2011 Fukushima Daiichi accident in Japan the IAEA made a valuable contribution to improving safety globally. Countries with nuclear power reassessed safety and made improvements in light of lessons learned from Fukushima. The future may offer new possibilities for nuclear power. Remarkable research and development is being done on new generations of reactors. The first advanced water-cooled reactors have already begun operations and more than 30 are under construction. These new designs enhance safety and reliability and are expected to improve economic competitiveness. The development of prefabricated small modular reactors or SMRs is well underway. They may offer flexible power generation for a wide range of users and applications. Fast reactors have the potential to ensure that energy resources will last thousands of years while reducing the volume and toxicity of waste. Nuclear fusion would harness the reactions that power the sun. It holds the promise of providing an inexhaustible, clean and safe source of energy. The IAEA fosters research and development for the advancement of nuclear reactor technology. The agency accompanies both experienced users and newcomers at every stage of their nuclear power journey. It helps member states enhance the safe and secure management of nuclear facilities and materials. And the IAEA advises on decommissioning plants at the end of their operational life. Our daily lives depend on a reliable supply of electricity. All countries need energy for economic growth while working to mitigate the effects of climate change. Nuclear power can help countries to meet their growing energy demands as well as their goals for reducing greenhouse gas emissions.