SDIC Gansu New Energy has officially commissioned the Akesai Huidong hybrid solar plant in Jiuquan, Gansu Province, China. This 750 MW facility integrates a 110 MW concentrated solar power (CSP) tower with a 640 MW photovoltaic (PV) solar array, making it the largest hybrid solar project in the country.
Thousands of mirrors, meticulously arranged in concentric circles, reflect sunlight onto a towering 195-meter (640-foot) concrete pillar rising from the desert sands. This impressive structure exemplifies the potential of CSP technology, which is experiencing renewed interest despite its challenges.
The Concept of Concentrated Solar Power (CSP)
Unlike traditional photovoltaic solar panels that directly convert sunlight into electricity, CSP harnesses the sun’s heat. Large mirrors, known as heliostats, focus sunlight onto a central receiver at the top of a tower. The concentrated heat is used to generate steam, which powers a turbine to produce electricity.
Inside the receiver, molten salt is often used as the heat transfer medium due to its excellent heat retention properties. The heated molten salt is circulated through the system, enabling consistent energy production even during periods of low sunlight or at night.
As Xavier Lara, a mechanical engineer with extensive experience in CSP, explains, “It’s the same kind of turbine you’d find in a fossil fuel power plant — but without burning any fossil fuels.”
Challenges That Hindered CSP’s Growth
CSP’s early promise was overshadowed by several challenges. Projects like the Crescent Dunes solar plant in Nevada highlighted the difficulties. Completed in 2015 to power 75,000 homes, Crescent Dunes failed to meet expectations due to technical issues and maintenance complexities. After prolonged outages, it shut down in 2019, damaging CSP’s reputation.
The rapid cost reduction of PV technology further eclipsed CSP. Since 2010, the cost of PV solar power has dropped by 90%, making it significantly cheaper and easier to deploy. Solar panels require minimal maintenance, while CSP systems involve complex engineering and precise alignment of mirrors to track the sun’s movement. Additionally, molten salt, the core of many CSP systems, poses risks; if it cools below its melting point, it solidifies, clogging the pipes and requiring extensive repairs.
Why CSP Still Holds Potential
Despite these setbacks, CSP offers one key advantage: its ability to store energy. Unlike PV panels, CSP plants can store heat in insulated tanks of molten salt, which cools at a slow rate of just 1°C (1.8°F) per day. This stored heat can be converted into electricity during the night or peak demand periods, addressing the “night gap” that limits many renewable energy sources.
“The future of CSP has shifted from being a direct competitor to PV to becoming more of a storage solution,” says Richard Thonig, a researcher at the German Research Centre for Geosciences.
China’s Push for CSP
China has embraced CSP as part of its renewable energy strategy, building over 30 CSP plants in recent years. The Akesai Huidong facility exemplifies this approach, combining PV for daytime electricity production with CSP for nighttime energy needs.
China’s policy mandates that new renewable energy parks with capacities exceeding 1 GW must include at least 10% energy storage. This has encouraged the integration of CSP and PV technologies, leveraging the strengths of both systems. The government has also pledged support for the “large-scale and industrialized development of solar thermal power,” aiming to establish dedicated supply chains that could reduce the costs of CSP plants.
The Future of CSP
While global CSP adoption remains limited, with only about 7 GW of capacity installed worldwide, China’s investments signal a potential revival of the technology. By bridging the gap between daytime and nighttime power generation, CSP could play a vital role in achieving a more reliable and sustainable energy grid.
“I wouldn’t say we’re seeing a CSP renaissance,” Thonig notes. “But the technology remains promising. With the right framework conditions, CSP can be cost-effective and valuable in many regions.”
As hybrid solar facilities like Akesai Huidong demonstrate, combining CSP with PV offers a pathway to maximize the efficiency and reliability of renewable energy systems. Whether CSP can regain global momentum will depend on further innovation, cost reductions, and supportive policies worldwide.