Energy is an important foundation for economic and social development. Mankind uses energy， historically we have converted energy sources from firewood to fossil such as coal， oil， and natural gas， to renewable energy such as hydro， wind and solar energy， every change is accompanied by a huge leap in productivity and major progress in human civilization. Energy， as the driving force for the development of modern society， contributes to the nation's economy and its citizens' interactive dynamic， as well as to their welfare. The massive development and use of traditional fossil energy has led to increasingly prominent problems such as resource shortages， environmental pollution， and climate change， which seriously threaten human survival and sustainable development. In essence， the core of sustainable development is clean development. The key is to promote renewable energy， and replace fossil energy with renewable energy such as solar， wind， and hydropower.
　　Scientific and accurate quantitative assessment of resources is the critical foundation for large-scale development and utilization of renewable energy. At present， the globally installed capacity of hydro， wind and solar power has exceeded 30% of the installed capacity of power sources， Although some achievements have been made in the development of renewable energy， there is still potential for it to expand. Therefore， it is of great importance to conduct a fine assessment on resource reserves. On the basis of establishing and improving the global renewable energy resources database， the Global Energy Interconnection Development and Cooperation Organization （GEIDCO） has established an assessment system and digital fine assessment models for renewable energy resources. These models carry out systematic calculation and quantitative assessment of theoretical potential， technical potential installed capacity and economic potential installed capacity of hydro， wind and solar energies from a global perspective. An achievement of the Global Renewable-energy Exploitation Analysis （GREAN） platform has been made， thereby the accuracy and timeliness of global renewable energy resources assessment will be effectively improved， subsequently providing an important support for large-scale development and utilization of renewable energy in relevant countries and regions.