Diversity of Reliability Attributes: A Key Component of the Modern Grid
Prepared for the American Petroleum Institute
The United States (“U.S.”) electric industry is currently in the midst of a transformation driven by technological innovation, changes in the industry’s cost structure, and environmental concerns. Throughout the latter half of the twentieth century, large coal, nuclear, and hydroelectric generators provided the bulk of the country’s electricity, while natural gas and oil generators operated only during peak demand hours. Variable energy resources, such as wind and solar photovoltaic (“PV”) generators, provided only a small portion of the nation’s electricity. Most generators could change output only very slowly, but because virtually all capacity was dispatchable and variations in load were both relatively small and highly predictable, the system operator could readily deal with changes in load.
