Gutting the duck: a CAM analysis of energy storage technologies for California's grid

Since California began decarbonizing its energy supply nearly 20 years ago, the state has become a leader in the clean energy revolution. Backed mostly by a rapid expansion of solar energy, California now generates more renewable energy than any other state in the nation. Although California’s growth in solar energy is impressive, it does not come without challenges. Most concerning of these challenges is grid imbalance between energy supply and energy demand over the course of a day. Referred to as the “duck curve,” the imbalance raises concerns about the grid’s ability to integrate more solar energy as California moves to a 100 percent carbon free energy supply. This thesis explores energy storage as one approach to address California’s duck curve and meet the state’s energy policy goals. More specifically, I look at four energy storage technologies and perform a criteria-alternative matrix (CAM) analysis to determine which storage technology best mitigates the duck curve while helping California achieve its energy goals. The thesis concludes that policymakers and regulators should implement the four following recommendations: Recommendation #1: Adopt an “all of the above” strategy in terms of storage technologies. Recommendation #2: Pursue underground CAES as a priority for utility-scale energy storage. Recommendation #3: Expand the use hydrogen fuel cells for increased grid flexibility. Recommendation #4: Reduce reliance on solar energy by classifying large hydro as “renewable” energy.