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A majority of U.S. states have enacted legislation requiring that renewable electricity make up as much as 25% of electric generation. In contrast to most conventional sources of power, electricity produced from wind and solar, the two most abundant sources of renewable power, are both variable and intermittent: variable because the wind does not blow all the time and clouds sometimes cover the sun, and intermittent, because there is no sun at all during the night. Today wind contributes roughly one percent and solar about one one-hundredth of a percent of all U.S. electricity generated. Biomass availability is also intermittent.

Proponents of renewables argue that large amounts of variable and intermittent power can be easily accommodated in the present power system. Opponents argue that even levels as low as 10% of generation by variable and intermittent power can cause serious disruptions to power system operation. This gap has not been bridged, in part because the level of advocacy required to enact renewables requirements has not been compatible with rigorous systems analysis.

A much-expanded role for variable and intermittent renewables is possible. But it will only happen if we adopt a systems approach that considers and anticipates the many changes in power system design and operation, while doing so at an affordable price, and with acceptable levels of security and reliability. There is a considerable risk that if we do not do the necessary planning, and develop the necessary new policy environment, serious problems could develop resulting in a major backlash against renewables in a decade or two. The U.S. cannot afford to let that happen. Reducing emissions of CO2 by 80% by mid-century will take everything we have got, including as much wind and solar as we can manage.

Building on the expertise of Carnegie Mellon's Electricity Industry Center and other research in the Department of Engineering and Public Policy, the Tepper School of Business and the Department of Electrical and Computer Engineering's Electric Energy Systems Group, and with co-investigators at the University of Vermont and the Vermont Law School, the RenewElec project will help the nation make the transition to the use of significant amounts of electric generation from variable and intermittent sources of renewable power in a way that:

  • Is cost-effective;
  • Provides reliable electricity supply with a socially acceptable level of local or large-scale outages;
  • Allows a smooth transition in the architecture and operation of the present power system;
  • Allows and supports competitive markets with equitable rate structures;
  • Is environmentally benign; and
  • Is socially equitable

Updated by Jeff Easter