California market designs for grid services to integrate renewable energy portfolios

California has adopted particularly ambitious goals for development and integration of renewable resources, reaching 20% by 2020 and 50% by 2030. Additional regulations require significant reductions in greenhouse gas emissions and elimination of once-through cooling at coastal power plants. In combination, California is experiencing major changes in its resource portfolio. The California ISO has responded to the challenges of these transitions by developing new market products including flexible ramping, load following, demand response, distributed energy resources, and storage, and in recognition that other states face similar issues, has opened its real-time energy market to new participants through its Energy Imbalance Market. These developments and remaining “next steps” are reviewed. References to supporting stakeholder processes are available at http://www.caiso.com/informed/Pages/StakeholderProcesses/Default.aspx.