This paper takes the Guazhou 700 MW “Solar Thermal plus Storage” project in Jiuquan City, Gansu Province, as a case study. The project belongs to China Three Gorges Corporation and Hengji Nengmai. It is one of the first batch of large-scale “desert, Gobi, and arid” wind and PV base projects. This project combines wind power, photovoltaic power, and concentrated solar thermal power within a single renewable energy system.
1. Overall Project Scale
The project has a total installed capacity of 700 MW. This includes 400 MW of wind power, 200 MW of photovoltaic power, and 100 MW of concentrated solar thermal power. These three components together form an integrated “wind, solar, and thermal” renewable energy system. The project leverages the complementary output characteristics of multiple energy sources to improve the overall power supply capability.
2. Wind Power Component
The project installs 400 MW of wind power. This represents the largest single power source within the entire project. The wind farm primarily harnesses the abundant wind resources in the Guazhou area. Wind turbines convert wind energy into electrical energy. Step-up transformers and collection lines then deliver the power to the booster system.
Guazhou belongs to an important wind power development region in Gansu Province. The area already has a large installed wind capacity. It also features well-developed transmission facilities for renewable energy. The wind power component connects to the power system together with the PV and solar thermal components. This arrangement helps reduce the impact of output fluctuations from a single wind project.
3. Photovoltaic Component
The project installs 200 MW of photovoltaic power. The solar power system utilizes the abundant solar resources in the Guazhou area. Large-area solar panels generate electricity. Solar inverters, step-up transformers, and collection lines then complete the power aggregation process.
Compared with wind power, PV generation concentrates mainly during daytime hours. Wind power generation, however, depends on wind conditions and is not limited to daytime. The two sources therefore offer a degree of temporal complementarity.
The wind and PV parts of the project have already achieved full-capacity grid connection. This provides a foundation for the subsequent joint operation with the solar thermal storage system.
4. Solar Thermal Storage Component
The project includes 100 MW of concentrated solar thermal power generation. This part adopts tower-type solar thermal technology. It constructs two heat absorption towers, each about 200 meters tall. The distance between the two towers is approximately one kilometer. The project equips about 27,000 heliostats. The total mirror field area reaches about 800,000 square meters. These heliostats track the sun’s position and concentrate solar energy onto the heat absorption towers for thermal conversion.
5. Dual-Tower Single-Turbine Technology
The solar thermal station adopts a “dual-tower, single-turbine” configuration. This means that two heat absorption towers jointly serve one steam turbine generator set. The two towers are arranged east-west, each about 200 meters tall, with a separation of about one kilometer. This configuration differs from the traditional single-tower, single-turbine approach.
Two heat collection systems supply thermal energy to one power generation system. This design improves the resource utilization efficiency of the solar thermal system. The project entered the full-system trial operation phase in 2025.
6. The Regulation Function of Solar Thermal Storage
The biggest difference between this project and ordinary wind-solar projects lies in its solar thermal system with energy storage and peak-shaving functions. Wind and PV outputs are subject to weather conditions. In contrast, the solar thermal system can store solar energy in the form of heat through molten salt storage during daytime hours.
When wind and PV outputs decline, the thermal storage system can release heat to generate electricity. This supplements the renewable energy output. As a result, the project forms a multi-energy complementary structure consisting of 400 MW wind, 200 MW PV, and 100 MW solar thermal storage.
7. Annual Power Generation
After the project reaches full operation, public data estimate that it will supply about 1.8 billion kWh of clean electricity to the grid annually. Based on the total installed capacity of 700 MW, this generation corresponds to an annual comprehensive utilization hours of approximately 2,570 hours. At the same time, the project is expected to save about 580,000 tons of standard coal each year. It will also reduce carbon dioxide emissions by about 1.53 million tons annually.
8. Project Construction Environment
Guazhou represents a typical desert region. New energy project construction there must contend with strong winds, sandstorms, and large diurnal temperature variations. Public reports indicate that the construction encountered difficulties such as complex site terrain and wind speeds exceeding operational limits.
As a result, large equipment lifting, PV module installation, and turbine construction all required scheduling according to local meteorological conditions. For the solar thermal system, the large heliostat field also demands high installation precision. This ensures that solar energy can be accurately concentrated onto the heat absorption system.
9. Multi-Energy Joint Operation
The engineering characteristic of this project does not simply divide 700 MW into three separate parts. Instead, it achieves complementarity through the output differences among various energy sources.
When solar resources are good during daytime, both PV and solar thermal can operate simultaneously. When wind conditions are favorable, the 400 MW wind power provides additional electricity. And when both wind and PV outputs decrease, the solar thermal storage can assume a certain regulation function. This operation model improves the overall power stability of the renewable energy base. It also reduces the risk of wind and solar curtailment.
10. Conclusion
The Guazhou 700 MW project consists of 400 MW wind power, 200 MW photovoltaic power, and 100 MW solar thermal power. It adopts “dual-tower, single-turbine” solar thermal storage technology. The project demonstrates a development direction from simple wind-solar complementarity toward joint operation of wind, solar, and storage systems.
