Electricity generation from renewable sources grows by 72 percent in the Reference case, raising its share of total generation from 11 percent in 2009 to 14 percent in 2035. Most of the growth in renewable electricity generation in the power sector consists of generation from wind and biomass facilities (Figure 3). The growth in generation from wind plants is driven primarily by State renewable portfolio standard (RPS) requirements and Federal tax credits. Generation from biomass comes from both dedicated biomass plants and co-firing in coal plants. Its growth is driven by State RPS programs, the availability of low-cost feedstocks, and the Federal renewable fuels standard, which results in significant cogeneration of electricity at plants producing biofuels.
Renewable electricity generation, excluding hydropower, accounts for nearly one-quarter of the growth in electricity generation from 2009 to 2035 in the AEO2011 Reference case (Figure 83). The increase is supported by renewable fuel standards, State-level renewable electricity standards, and Federal tax credits. In the Reference case, generation from wind power nearly doubles its share of total generation, while generation from geothermal resources triples as a result of technology advances that make previously marginal sites attractive for development, as well as increasing the resources available at existing geothermal sites.