Biomass—The contribution of biomass to electricity production versus the use of the biomass energy resource base for the production of liquid fuels;
Transmission—The mechanisms and responsibilities for increases in transmission capacity and other upgrades for the electricity grid; and
Transportation—The degree to which renewable electricity can influence the transportation sector and reduce dependence on imported oil and liquefied natural gas through, in the near term, charging vehicle batteries and, in the long term, producing non-petroleum-based fuels.
A future characterized by a large penetration of renewable electricity represents a paradigm shift from the current electricity generation, transmission, and distribution system. There are many reasons why renewable electricity represents such a shift, including the spatial distribution and intermittency of some renewable resources, and issues related to greatly increasing the scale of deployment. Wind and solar, renewable energy resources with the potential for large near-term growth in deployment, are intermittent resources that have some of their base located far from demand centers. The transformations required to incorporate a significant penetration of additional renewables include transformation in ancillary capabilities, especially the expansion of transmission and backup power resources, and deployment of technologies that improve grid intelligence and provide greater system flexibility. Further, supplying renewable resources on a scale that would make a major contribution to U.S. electricity generation would require vast investment in and deployment of manufacturing and human resources, as well as additional capital costs relative to those associated with current generating technologies that have no controls on greenhouse gas emissions. The realization of such a future would require a predictable policy environment and sufficient financial resources.
Nevertheless, the promise of renewable resources is that they offer significant potential for low-carbon generation of electricity from domestic sources of energy that are much less vulnerable to fuel cost increases than are other electricity sources. Overall success depends on having technology, capital, and policy working together to enable renewable electricity technologies to become a major contributor to America’s energy future.