The National Renewable Energy Laboratory (NREL) released Phase 2 of the Western Wind and Solar Integration Study (WWSIS-2), a follow-up to the initial WWSIS released in May 2010, which examined the viability, benefits, and challenges of integrating as much as 33% wind and solar power into the electricity grid of the western United States. Grid operators have always cycled power plants to accommodate fluctuations in electricity demand as well as abrupt outages at conventional power plants, and grid operators use the same tool to accommodate high levels of wind and solar generation. WWSIS found adding greater amounts of wind and solar power to be technically feasible if certain operational changes could be made, but it raised questions regarding the impact of added cycling on power plant wear-and-tear costs and emissions.

Funded by the Department's Wind Program, Solar Technologies Office, Office of Electricity Delivery and Energy Reliability, and NREL, the new study found that incorporating these renewable energies did increase cycling, but the increased costs and emissions generated from cycling were small compared to reductions resulting from less fossil fuel use.

  • The study finds that the carbon emissions induced by more frequent cycling are negligible (<0.2%) compared with the carbon savings reductions achieved through increased wind and solar power generation.
  • Compared to the study's business-as-usual scenario, sulfur dioxide emissions reductions from increased wind and solar are 5% less than the baseline and nitrogen oxide emissions are 2% less than the baseline due to cycling of fossil-fueled generators.
  • The study also finds that high levels of wind and solar power would reduce fossil fuel costs by approximately $7 billion per year across the west, while incurring cycling costs of $35 million to $157 million per year.

You can find both the Western Wind and Solar Integration Study Phase 2 report and a fact sheet summarizing it on the Wind Program's updated Renewable Systems Integration R&D Web page.