Growth in renewable energy in the U.S. over the past decade has been propelled by a number of forces, including rising fossil fuel prices, environmental concerns, and policy support at the state and federal levels. In this article, we review and discuss what are arguably the two most important...

Renewables portfolio standards (RPS) have proliferated at the state level in the United States since the late 1990s. In combination with Federal tax incentives, state RPS requirements have emerged as one of the most important drivers of renewable energy capacity additions. The focus of most RPS...

Markets for renewable electricity have grown significantly in recent years, motivated in part by federal tax incentives and in part by state renewables portfolio standards and renewable energy funds. State renewables portfolio standards, for example, motivated approximately 45% of the 4,300 MW...

Renewable energy certificates (RECs) are tradable instruments that convey the attributes of a renewable energy generator and the right to make certain claims about energy purchases. RECs first appeared in US markets in the late 1990s and are particularly important in states that accept or...

Markets for renewable energy have historically been motivated primarily by policy efforts, but a less widely recognized driver is poised to also play a major role in the coming years: utility integrated resource planning (IRP). Resource planning has re-emerged in recent years as an important...

Renewable energy certificates (RECs) represent the bundle of information that describes the characteristics of renewable electricity generation, and may be (and increasingly are) sold separately from the underlying electricity itself. RECs are a relatively new phenomenon, emerging as a tradable...

Voluntary markets for ''green'' power, and mandatory policies such as fuel source disclosure requirements and renewables portfolio standards, each rely on the ability to differentiate electricity by the ''attributes'' of the generation. Throughout North America, electricity markets are devising...