China's Gobi Solar Plant Utilizes Molten Salt for Post-Sunset Power, Bypassing Batteries
China Three Gorges Corporation (CTG) has inaugurated the world's largest integrated solar photovoltaic and concentrated solar power (CSP) facility in the remote Gobi Desert. This groundbreaking project distinguishes itself by delivering electricity after sundown through a molten salt energy storage system, rather than conventional lithium-ion batteries. The Hami complex in Xinjiang represents a significant leap in renewable energy technology, offering a solution to the intermittency of solar power.
The Hami project, a 1-gigawatt behemoth, combines 900 megawatts of standard solar panels with a 100-megawatt concentrated solar power unit. Spanning 1,817 hectares at the foot of the Tianshan mountains, this facility involved an investment of approximately $480 million. During daylight hours, the vast array of PV panels supplies the grid with electricity. Simultaneously, the CSP unit employs 260,000 tracking mirrors, covering 800,000 square meters, to focus sunlight and heat molten salt to an impressive 550°C. This captured thermal energy is then stored, ready to be converted into steam to drive a turbine once the sun sets, providing power for up to eight hours.
It is crucial to note that the post-sunset power output, lasting for up to eight hours, originates specifically from the 100 MW CSP component, not the entire gigawatt capacity. This demonstrates a dispatchable evening block of power, tackling solar's primary challenge of nighttime generation. The plant's reliance on thermal storage, as opposed to batteries, highlights an alternative strategy for energy resilience. CTG has implemented a linear Fresnel design for the CSP section, which reportedly enhances heat-conversion efficiency by up to 10% compared to traditional Fresnel systems. Additionally, a 46-loop layout ensures continuous operation even during maintenance periods. A sophisticated centralized control system manages the output between the PV and thermal sections, maintaining precise frequency regulation and rapid response times.
While the project officially commenced commercial trial operations on July 1, its connection to the grid dates back to September 18, 2025. Since then, it has maintained a continuous load, feeding 6.54 million kWh into the regional grid. At its maximum capacity, CTG anticipates the complex will generate 2.07 TWh of electricity annually, sufficient to power roughly 830,000 homes. This output is also projected to reduce carbon dioxide emissions by approximately 1.63 million tons each year and boost Xinjiang's renewable energy utilization rates beyond 95%. This achievement surpasses the 950 MW Noor Energy 1 plant in Dubai, making Hami the world's largest CSP-PV hybrid facility.
The debate between molten salt thermal storage and lithium-ion batteries centers on their respective applications. Niu Jianle, project director for the CTG Hami project, emphasizes that lithium batteries are primarily suited for short-duration peak shaving, while CSP thermal storage excels in large capacity, extended discharge cycles, and zero operational emissions. He views the grid connection as a monumental step, transitioning the technology from laboratory research to extensive commercial implementation. The main hurdle for CSP technology has traditionally been its cost-effectiveness compared to PV-plus-battery systems, especially as lithium battery prices continue to decline. The true measure of Hami's success will be its ability to provide affordable power for an extended duration over many years, outperforming the rapidly evolving battery market.
China is heavily invested in this technology, with CTG planning to expand the Hami facility to 3 GW in a subsequent phase. Furthermore, China Energy Engineering Corp has initiated construction on a neighboring 1.5 GW hybrid project, comprising 1.3 GW of PV and 150 MW of CSP, which is poised to surpass Hami's capacity upon completion. This aggressive development underscores China's commitment to industrializing molten-salt storage at a utility scale, a strategy that many other nations have largely overlooked in favor of battery solutions. While CSP's levelized cost has historically lagged behind PV-plus-lithium, the continued innovation and large-scale deployment in China present an intriguing case study for the future of renewable energy storage. The Hami project, despite some skepticism regarding its overall contribution compared to its battery counterparts, undeniably represents a significant engineering feat and a valuable exploration into diverse energy storage solutions.