Characterizing Opportunity Power in the California Independent System Operator (CAISO) in Years 2015-2017

Abstract

Studying the California Independent System Operator (CAISO) day-ahead and real-time markets for the period January 2015 to December 2017, we characterize the growth of curtailment and negative-priced power from renewable generators. Results show that renewable curtailment is growing rapidly, tripling to over 400 GWh from 2015-2018. Negative-priced renewable power is larger and also growing rapidly, reaching 1.5 TWh in 2017 for 40% CAGR.

Resource-hours for negative pricing grew nearly 3-fold from 80,006 to 217,728 hours, with the highest single generator reaching 955 hours in 2017 or 33% of the daylight solar hours. Spatially, the quantity of negative-priced power is concentrated at a few dozen renewable generators, reaching peaks of 170GWh at the largest generator. We also consider an averaged-price model (NetPrice) that smooths over fluctuations to estimate the usable quantities of low-priced power. Results for NetPrice show a much larger quantity of low-priced power available than with either negative-pricing or curtailment alone. Overall, these results suggest both that opportunity power is a substantial and growing resource and a number of opportunities to exploit it.