Private companies are expected to drive the development of trading markets for reducing greenhouse gas emissions and promoting renewable energy and energy efficiency. To make these markets grow, consistent measures and price standards are needed. Different options like exchanges, bilateral transactions, or listing on markets can be used to trade emissions rights. The Kyoto Protocol planned emissions trading to help countries cut emissions. The U.S. has a market for trading emissions like CO2. The structured finance market or Green Finance can support emissions trading. The renewable energy credit market looks promising for future trading. The trading of environmental commodities could become a $3 trillion market involving big energy companies.