To better assess the prospects for individual renewable electricity technologies, the panel separated its consideration of these technologies and their characteristic costs, performance, and impacts into three time periods: an initial period that considers present technologies out to the year 2020; a second that considers current and potential renewable electricity technologies over the 2020 to 2035 time period; and a third period that looks at technologies beyond 2035.
For the time period from the present to 2020, there are no current technological constraints for wind, solar photovoltaics and concentrating solar power, conventional geothermal, and biopower technologies to accelerate deployment. The primary current barriers are the cost-competitiveness of the existing technologies relative to most other sources of electricity (with no costs assigned to carbon emissions or other currently unpriced externalities), the lack of sufficient transmission capacity to move electricity generated from renewable resources to distant demand centers, and the lack of sustained policies. Expanded research and development (R&D) is needed to realize continued improvements and further cost reductions for these technologies. Along with favorable policies, such improvements can greatly enhance renewable electricity’s competitiveness and its level of deployment. Action now will set the stage for greater, more cost-effective penetration of renewable electricity in later time periods. It is reasonable to envision that, collectively, non-hydropower renewable electricity could begin to provide a material contribution (i.e., reaching a level of 10 percent or more, with trends toward continued growth) to the nation’s electricity generation in the period up to 2020 with such accelerated deployment. Combined with hydropower, total renewable electricity could approach a contribution of 20 percent of U.S. electricity by the year 2020.
In the period from 2020 to 2035, it is reasonable to envision that continued and even further accelerated deployment could potentially result in non-hydroelectric renewables providing, collectively, 20 percent or more of domestic electricity generation by 2035. In the third timeframe, beyond 2035, continued development of renewable electricity technologies could potentially provide lower costs and result in further increases in the percentage of renewable electricity generated from renewable resources. However, achieving a predominant (i.e., >50 percent) level of renewable electricity penetration will require new scientific advances (e.g., in solar photovoltaics, other renewable electricity technologies, and storage technologies) and dramatic changes in how we generate, transmit, and use electricity. Scientific advances are anticipated to improve the cost, scalability,