New Study Reveals Multiple Pathways to 30% Penetration of Wind and Solar

September 16, 2015

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A new study published by the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) found that the U.S. Eastern Interconnection—one of the largest power systems in the world—can reliably support up to a 30% penetration of wind and solar power. Using high-performance computing capabilities and new methodologies, researchers at NREL conducted the Eastern Renewable Generation Integration Study (ERGIS) and modeled hundreds of gigawatts of wind and solar on system operations to examine their impacts on other generation sources such as thermal plants.

The high-performance computing center at NREL enabled the ERGIS team to increase the resolution of the analysis in several key ways:

  • Expand the range of resources analyzed by simulating large-scale adoption of solar in addition to wind in the U.S. Eastern Interconnection
  • Increase the temporal resolution to 5 minutes to understand the subhourly impact of these resources on system operations
  • Increase the spatial resolution of the model to include all synchronous components of the Eastern Interconnection and the Québec Interconnection on a comparable basis
  • Reduce scenario solve times from 545 to 20 days.

To determine the impacts of wind and solar on the Eastern Interconnection, the research team simulated four scenarios, each of which was compared to a baseline scenario that reflects current wind and solar deployment:

  1. A low variable generation scenario that 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
  2. A regional transmission 10% variable generation scenario that builds out wind and solar generation to meet 10% of the interconnection’s load with a regional transmission expansion
  3. A regional transmission 30% variable generation scenario that 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
  4. An interregional 30% variable generation scenario that chooses the best resources in terms of quality and price in the Eastern Interconnection to meet the 30% target and includes a substantial build-out of new interregional transmission facilities.

The study found that there are multiple pathways to achieve a 30% penetration of wind and solar in the Eastern Interconnection and that the simulated levels of wind and solar can be balanced across the entire Eastern Interconnection, including Canada, during normal operations. The study also found that:

  • Efficient utilization of available wind and solar depends on transmission availability and characteristics of the generation fleet
  • Annual wind and solar penetrations of 30% decrease production costs and emissions by approximately 30%
  • Wind and solar significantly impact the operation of traditional generation sources in the Eastern Interconnection in three key ways:
    • The overall dispatch of thermal generation decreases
    • Variable generation causes thermal generators to ramp and start more frequently
    • Typical daily operating patterns of generators change.                        

Wind and solar primarily displace coal and combined-cycle natural gas generation. ERGIS simulations show that annual variable-generation penetrations of 30% decrease coal, combined-cycle, and combustion turbine capacity factors by about 50%.

Learn more about DOE’s wind grid integration research efforts.