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Western Wind and Solar Integration Study Phase 2 Research

Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2) was initiated to determine the wear-and-tear costs and emissions impacts of cycling and to simulate grid operations to investigate the detailed impacts of wind and solar power on the fossil-fueled fleet in the West.

Key Findings

  • The negative impact of cycling on overall plant emissions is relatively small. The increase in plant emissions from cycling to accommodate variable renewables are more than offset by the overall reduction in CO2, NOx, and SO2. In the high wind and solar scenario, net carbon emissions were reduced by one third.

    Table comparing emission reductions due to renewables with emissions due to cycling impact

    The increase in plant emissions from cycling to accomodate variable renewables are more than offset by the overall reduction in CO2, NOx, and SO2.

  • Operating costs increase by 2–5% on average for fossil fueled plants when high penetrations of variable renewables are added to the electric grid.

    Graph illustrating that operating costs increase from .50 $/MWh to approximately 3.30 $MWh at fossil fueled plants when renewables are added to the mix.

    From a fossil fuel generator perspective, cycling costs increase with increased wind and solar penetration.

  • From a system perspective, these increased costs are relatively small compared to the fuel savings associated with wind and solar generation.

    Graph illustrating that from a system perspective, operating costs decrease when renewables are added to the mix.
  • Cycling costs vary based on penetration level and wind/solar mix.

    Table showing cycling cost data for each study scenario.

Phase 2 Publications