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July 06, 2015
Report by Brattle Economists Examines Feasibility of Integrating Variable Renewable Energy into Electric Grid

A new report authored by Brattle principals Jürgen Weiss and Bruce Tsuchida finds that the integration of high levels of variable renewable energy into the electric grid is both technically feasible and can be managed without compromising reliability of electric power service.

Through two in-depth case studies – the Electric Reliability Council of Texas (ERCOT) and Xcel Energy Colorado – the authors find that integrating variable renewable energy at penetration levels of 10-20% on average and at times above 50% (i.e., high relative to the current levels throughout most of the United States) is possible. Additionally, both ERCOT (and the distribution utilities in ERCOT) and Xcel Energy Colorado have managed to successfully integrate increasing amounts of variable renewable energy resources at costs that have generally been small to modest.

The Brattle report also finds that deploying new and innovative solutions can further mitigate the challenges of integrating variable renewable generation, at least in some cases with significant cost savings compared to traditionally used integration approaches. The authors identify a range of methods and technologies used by ERCOT and Xcel Energy Colorado that, if adopted by other U.S. ISOs/RTOs and utilities, can help with integrating increasing shares of variable renewable generation. These include:

  • changes in ancillary services, which manage short-term mismatches between electric supply and demand, with fast-ramping gas-fired generation, demand response, storage, and other technologies;
  • improved forecasting of production from wind;
  • increased flexibility of fossil power plants on the system;
  • evolving capabilities of renewable generation itself to contribute to reliability;
  • expansion of transmission infrastructure; and
  • newer approaches under development, which include utilizing large-scale storage, dynamically managing the capacity of transmission lines, and allowing demand response to play a bigger role in managing system variability (and emergency situations).
“Integrating Renewable Energy into the Electricity Grid: Case studies showing how system operators are maintaining reliability,” was prepared for the Advanced Energy Economy Institute (AEEI), and is available for download below.