An Estimation Model for the Number of EVs Required to Utilize V2G Technology

Renewable energy generation continues to grow, but its variability problem remains. Battery energy storage is one potential way to solve this problem and more efficiently utilize existing renewable energy infrastructure. While grid level battery projects have begun, vehicle to grid (V2G) interaction with electric vehicles (EV) could add a significant amount of energy storage. This work estimates the number of electric vehicles needed to efficiently utilize variable renewable energy resources in California using V2G interaction. Efficient use of variable renewable energy resources is defined for this paper as creating a constant power demand for conventional energy generators, as opposed to variable demand resulting from renewable energy fluctuations. While the data analyzed is specific to California, the models used and overarching "Vision for Participation" can be applied to any interconnected power network. To estimate the number of EVs required, an analytical approach is developed to create a constant difference between the daily renewable energy generation and consumer demand profiles over the course of an average day using battery storage. This difference will not only be useful as a metric for renewable energy growth, but will help utilities more efficiently dispatch their conventional generators and size their conventional portfolio. Battery deterioration is a critical component of V2G since there would need to be some transaction incentivizing EV owners to participate in powering the grid in the previously mentioned way. While this work does not provide specific pricing to EV participants, it does quantify battery deterioration on a per-charge basis, which could inform future pricing models for grid interaction. The parametric model of the capacity fade of an EV battery is developed using a combination of laboratory data and EV usage data for the most common lithium ion battery chemistry, NCA. The analysis of these two models suggest that a total of 1-2 million EVs (there are currently around 600,000) are required to effectively use V2G technology to efficiently utilize the renewable energy capability of California.