Reliability of Electric Power from Geographically Dispersed Wind and Solar Resources

EPA Grant Number: F6C20124
Title: Reliability of Electric Power from Geographically Dispersed Wind and Solar Resources
Investigators: Fripp, Matthias
Institution: University of California - Berkeley
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2006 through September 1, 2009
Project Amount: $110,124
RFA: STAR Graduate Fellowships (2006) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Geography , Pollution Prevention/Sustainable Development , Ecological Indicators/Assessment/Restoration


Wind and solar power can provide clean, secure energy in the U.S. However, wind speeds and solar irradiance vary with weather and the time of day, and it is unclear how these energy sources will affect the reliability of the power system if they are used to meet a large share of our electricity requirements. I will conduct the first study to assess the reliability of the combination of wind and solar power, when collected from all possible locations in a large electric grid.


I will use new datasets of historical weather conditions from the National Centers for Environmental Prediction and NASA to drive a simulation of wind and solar power output at all promising locations throughout the state of California, every 3 hours over a 12-year period. The time-varying, statewide renewable power output from this simulation will then be incorporated into a model of the electric power system, to assess which other generators can be displaced in both the short and long term by renewable power equipment, while maintaining the power system’s current level of reliability. This analysis will reveal the amount of power that the renewable equipment can provide reliably and economically, without the need for dedicated backup generators. I will repeat this assessment with renewable sources dispersed across large and small geographic areas, and with different ratios of wind and solar power, to measure how the reliable supply of renewable power changes as the collection area is expanded, and as wind and solar power are combined. This research can later be extended to other regions of the U.S.

Expected Results:

This research will quantify for the first time the effect of combining wind and solar power, as well as combining renewable power from multiple locations, in order to provide a more robust understanding of how intermittent renewable energy sources will affect the electric power system. This will allow planners and policymakers to make a more orderly, confident transition to using renewable energy than would otherwise be possible. In addition, this research is likely to show that the collective output of renewable power from widely dispersed locations will be more reliable than the power currently generated by wind farms or solar equipment at any individual location, because some locations will have strong winds or clear skies when others do not. This conclusion could lead to adoption of higher targets for the use of renewable energy, allowing our society to use renewable power to reduce its environmental emissions further than previously thought.

Supplemental Keywords:

renewable energy, wind, solar, intermittency, electricity, geographic dispersion,, RFA, Scientific Discipline, TREATMENT/CONTROL, Sustainable Industry/Business, POLLUTION PREVENTION, Sustainable Environment, Energy, Technology, Technology for Sustainable Environment, Environmental Engineering, energy conservation, environmental technology, clean technologies, environmental sustainability, energy efficiency, energy technology, solar energy, alternative energy source, wind energy, wind power

Progress and Final Reports:

  • 2007
  • 2008
  • Final