Solar Experts Offer a Solution to Satisfy Both Sides in Ivanpah Decommissioning Battle

Two California electric utilities, Pacific Gas & Electric (PG&E) and Southern California Edison, have sought to terminate long-term power purchase agreements (PPAs) for the Ivanpah solar thermal power plant, citing underperformance and high operational costs. Since its commissioning in 2014, Ivanpah has delivered only about 70 to 80 percent of its expected annual generation. The California Public Utilities Commission (CPUC) has, however, rejected PG&E’s proposed contract terminations, emphasising the importance of maintaining clean energy sources amid rising electricity demand and the significant investments already made in associated infrastructure. Ivanpah is a pioneering concentrated solar power (CSP) tower project that notably lacks thermal energy storage, a limitation that has contributed to its economic challenges. Researchers from the National Laboratory of the Rockies highlight that Ivanpah’s direct steam system prevents it from storing energy, making it inflexible and vulnerable to fluctuations in solar radiation. This design flaw has resulted in the plant generating electricity primarily during midday when solar output is abundant but electricity prices are often low or even negative, undermining its profitability in a market increasingly valuing dispatchable and flexible power sources. Despite these operational setbacks, Ivanpah’s heliostat field—the array of mirrors that concentrate sunlight onto the central tower—has been a technical success. The solar field has demonstrated high availability and precise control, validating the scalability and reliability of heliostat technology. The core issue lies in the plant’s heat generation and storage system, which has struggled to deliver consistent output due to its direct steam design and lack of thermal storage, necessitating natural gas use during start-up and standby periods. Experts propose a retrofit solution that would preserve the high-performing heliostat field while replacing the direct steam receiver with a molten salt system that includes 12 hours of thermal energy storage. This upgrade could significantly improve Ivanpah’s economic viability by enabling the plant to store heat and dispatch electricity more flexibly, aligning with current market demands. Modelling indicates that such a retrofit could increase the plant’s internal rate of return by 30 percent compared to its original configuration, potentially satisfying both the utilities’ need for a profitable asset and the CPUC’s mandate to maintain renewable capacity. The broader concentrated solar power industry has learned from Ivanpah’s early challenges, with nearly all new CSP facilities constructed since incorporating molten salt thermal storage as standard. This evolution underscores the potential for Ivanpah to be revitalised through modern technology, offering a path forward that balances economic and environmental objectives while supporting California’s ambitious renewable energy targets.