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New Study Reveals Potential 30% Penetration of Wind and Solar for the Eastern Interconnection

August 10, 2015

Using high-performance computing capabilities and new methodologies to model operations of the Eastern Interconnection—arguably the largest power system in the world—at unprecedented fidelity, NREL found that the power system can reliably support up to 30% penetration of wind and solar power.

Wind is one of the fastest growing electricity resources in the United States and in the U.S. Eastern Interconnection, as is solar. The U.S. Department of Energy (DOE) commissioned NREL to study the operational impacts of higher percentages—up to 30% penetration on an annual energy basis—of combined wind and photovoltaic (PV) generation.

The result was the Eastern Renewable Generation Integration Study (ERGIS), a scenario-based study of four potential wind and PV futures and associated operational impacts (forthcoming).

Aaron Bloom, senior project manager at NREL said, “What we looked at was the operational impact of hundreds of gigawatts of wind and solar on system operations. Then we asked a series of questions: How does it change the operations of other generators, like the thermal plants? Do they ramp more, do they start up and shut down more, are they sitting online at idle more often, or are they running full bore all the time? So we wanted to see what happens to the other power plant assets when you add all these renewables. We determined it could be done.”

The four scenarios studied were:

  • A low variable generation scenario, which holds the current amount of wind and solar power constant, removes generators slated for retirement, and adds new generators to meet the load and maintain reliability, as needed.
  • A regional transmission 10% variable generation scenario, which builds out wind and solar generation to meet 10% of the interconnection's load with a regional transmission expansion.
  • A regional transmission 30% variable generation scenario, which requires wind and solar generation within each of the ERGIS regions to provide 30% of the region's power. This scenario shares the same transmission expansion as the second scenario.
  • An interregional 30% variable generation scenario, which chooses the best resources in the Eastern Interconnection to meet the 30% target and includes a substantial build-out of new interregional transmission facilities.

Here are five key conclusions of the study.

  • Simulated levels of wind and PV generation can be balanced across the entire Eastern Interconnection, including Canada, during normal operations—at the nodal level and 5-minute resolution.
  • Multiple pathways lead to 30% penetrations of wind and PV in the Eastern Interconnection.
  • Efficient utilization of available wind and PV depends upon transmission availability and characteristics of the generation fleet.
  • Annual wind and PV penetrations of 30% decrease production costs and emissions by approximately 30%. Evaluation of capital costs associated with the generation or transmission expansion was beyond the scope of ERGIS. Further economic analysis is necessary to determine the total cost of achieving these reductions.
  • Wind and PV significantly impact the operation of traditional generation sources in the Eastern Interconnection.

—Kelly Yaker