A second type of scenario examines how renewables interact with other sources of electricity, other sources of energy, and end-use energy demands (CCSP, 2007; EIA, 2008a). Through the use of long-term energy–economic models, these scenarios enable assessment of the potential impacts of demographic, economic, and regulatory factors on renewable electricity within a framework that considers the whole energy sector. The scenarios described here are used to explore issues such as:

• How wider energy–economic interactions and the electricity market could affect market penetration by renewables;

• The impacts of environmental, economic, and/or energy policies on end-use demand and electricity generation from renewables and other sources.

These scenarios, as with the reference case scenario presented in Chapter 1, are not predictors of the future, and the results of scenarios are not forecasts. Rather, they are descriptions of one set of conditions that could result in significantly increased market penetration by one or several renewables over what is estimated based on present-day conditions and a business-as-usual future. They demonstrate the costs, benefits, and scale of the challenges associated with increasing the integration of renewables into the electricity sector.

The American Wind Energy Association and DOE’s National Renewable Energy Laboratory (NREL) developed a scenario assuming that 20 percent of electricity generation would come from wind power by 2030 (DOE, 2008). The scenario included assessments of the wind resource base, materials and manufacturing requirements, environmental and siting issues, transmission and system integration, costs, and public policy drivers (Smith and Parsons, 2007). The scenario estimated that more than 300 GW of new wind power capacity would be needed to meet a goal of 20 percent market penetration by wind, of which about 250 GW would be installed onshore and 50 GW installed offshore. Under this scenario, in 2030 wind power would produce about 1.2 million GWh out of a total U.S.