The largest electricity system control area in the United States has implemented a tracking system for renewables generation. Dubbed the Generation Attribute Tracking System (GATS), it will record emissions data, fuel source, location, state program qualification and ownership for each megawatt hour produced in states covered by PJM Interconnection. PJM is a regional transmission organisation that serves 51 million people in all or parts of Delaware, Indiana, Illinois, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia. A subsidiary, known as PJM EIS, was created to handle the GATS database. When power is generated, its attributes are recorded in a database and a unique serial number for that megawatt hour is produced. That allows tracking by certificate of renewable energy for such uses as documenting claims about green power and paves the way for trading certificates within the PJM area. "Developing and launching the GATS has been a win for everyone," says Kenneth W. Laughlin, president of PJM EIS. "It allows states to implement energy policy and it allows energy sellers to meet the state's requirements. It allows renewable generators to monetize the environmental value of their production."