Power plants subject to a regional cap-and-trade program in the northeastern U.S. known as the Regional Greenhouse Gas Initiative (RGGI) reduced their carbon dioxide emissions by an average of 23 percent during the first three years of the program, the group says. According to a RGGI report, 206 of 211 power plants participating in the program met their compliance obligations from Jan. 1, 2009 to Dec. 31, 2011, the first three-year control period of the program. During that time, the average annual CO2 emissions were 126 million tons, a 23-percent decline compared with the previous three-year period. Emissions for the 2009-2011 period were about 33 percent below RGGI’s annual pollution cap of 188 million tons, which was due to a shift from coal to natural gas, the economic recession, and energy efficiency programs. The RGGI regime requires major power plants to buy allowances at auction for each ton of carbon dioxide they emit. Companies that emit lower emissions can sell their unused allowances to other companies. Program participants include the six New England states and New York, Delaware, and Maryland.