This year marks the fifth anniversary of the implementation of the major national strategy for the Yellow River. Dazhong Daily and Dazhong News, together with the Party media of the nine provinces and regions along the Yellow River and the Party media of 16 cities in Shandong, launched a joint all-media reporting campaign. Reporters selected nine landmark points along the 10,000-li Yellow River and conducted around-the-clock observation, using small details to reflect the broader changes in ecological protection and high-quality development in the Yellow River Basin. In this report, the "Walking the Yellow River" reporter conducted on-site observation at a key location in the national new energy development strategic layout—the Qaidam Desert Base—visiting the "super mirror power station" and getting close to the Shandong builders on the project.
You live at the head of the Yellow River, I live at its tail. One west, one east—Qinghai and Shandong are both already leaders in China's green energy transition.
A tower-type concentrated solar power (CSP) station is sometimes called a "super mirror power station." Among a group of benchmark CSP projects in Qinghai, we found the presence of Shandong builders. Following this lead, we traveled to Qinghai and visited a key location in the national new energy development strategic layout—the Qaidam Desert Base.
On October 19, the civil construction work of the China General Nuclear Power Group (CGN) Delingha 2-million-kilowatt CSP-storage integrated project was nearing completion and was about to fully enter the installation phase. (Reported by Dazhong News reporter Tang Laibu)
The Best Sunlight and the Most Abundant Salt Lake
Early in the morning of October 17, the temperature in Golmud City, Haixi Mongolian and Tibetan Autonomous Prefecture, Qinghai Province, had dropped below zero. Local taxi driver Shi Zhongzhen told reporters that the heating season had already begun and would last until May next year, "but the sunlight here is especially good, and the roads rarely have accumulated snow."
Golmud City is one of the areas with the richest solar resources in China, and Qarhan Salt Lake, China's largest salt lake, is also located here. The brine in the salt lake can be extracted and processed into potassium nitrate and sodium nitrate, then processed into molten salt to become the energy storage medium for CSP stations, storing green energy. "The land in the Qaidam Basin is relatively flat, and the molten salt resources, a key material for CSP, rank first in the country, giving the region unique advantages for developing CSP," said Ye Cheng, deputy director of the New Energy Division of the Qinghai Provincial Energy Administration.
Heading east from downtown Golmud and crossing the vast Gobi Desert, we arrived at the China Green Development Haixi Prefecture Multi-Energy Complementary Integration and Optimization National Demonstration Project (hereinafter referred to as the "Green Development Haixi Multi-Energy Complementary Project"). Its 50,000-kilowatt tower-type CSP station was invested in by China Green Development Investment Group Co., Ltd. and built under general contracting by Shandong Electric Power Construction No. 3 Engineering Co., Ltd. of Power Construction Corporation of China (hereinafter referred to as "SEPCOIII").
At 8 a.m., entering the project base and passing through 4,400 heliostats arranged in layers around the site, we arrived beneath the 188-meter-tall receiver tower at the center of the CSP station, as if standing in a science fiction film.
How does a CSP project operate? Heliostats reflect sunlight onto the receiver at the top of the tower, and the molten salt is rapidly heated to 565°C. The high-temperature molten salt is stored in large molten salt tanks and, according to grid demand, exchanges heat with water to produce high-temperature, high-pressure steam that drives a steam turbine to generate electricity.
On the afternoon of October 17, at the Green Development Haixi Multi-Energy Complementary Project, the top of the towering molten salt tower was "lit up" by sunlight reflected from the heliostats. (Reported by Dazhong News reporter Tang Laibu)
At this time, Wang Xiaobing and Cao Jianping, workers from the heliostat cleaning team who had just finished their morning meeting, were driving cleaning vehicles to the mirror field around the CSP tower. The cleanliness of the mirror surfaces is crucial to the light-concentrating effect of a CSP station and directly affects the solar-to-heat conversion efficiency and the station's power generation. The cleaning team works in pairs: one guide and one driver. The sandy ground of the mirror field is soft, and each mirror has an area of 138 square meters. To prevent the vehicle from bumping and damaging the mirrors, a guide must walk in front of the vehicle to lead the way. Cleaning more than 200 mirrors a day requires the guide to trek nearly 20,000 steps over the sandy ground, stumbling along the way.
Entering November, this work will become more complicated. Hua Yisen, head of the CSP station, said that after local daily temperatures drop below zero, the water sprayed will freeze on the mirror surfaces, greatly reducing cleaning efficiency. In addition, local water is relatively hard, and softening it requires electricity and specialized chemicals, increasing costs. Since this summer, Hua Yisen has been designing a "dry cleaning" solution. "At present, the brush-and-water cleaning method is already very water-saving, but we should save wherever we can."
Unlike intermittent and fluctuating new energy sources such as photovoltaics and wind power, a CSP station concentrates and stores heat during the day and releases heat to generate electricity at night, without affecting grid security or the consumption of new energy. It is equivalent to a large, stable thermal "power bank."
"Sufficient peak-shaving resources are a prerequisite for the efficient use of renewable energy and the optimization of the energy structure," said Wang Zhifeng, a researcher at the Institute of Electrical Engineering of the Chinese Academy of Sciences and director of the CAS Key Laboratory of Solar Thermal Utilization and Photovoltaic Systems.
Taking the Green Development Haixi Multi-Energy Complementary Project as an example, through in-depth research and construction of CSP, shared energy storage, liquid air energy storage, and grid-forming energy storage, the project's overall curtailment rate of wind and solar power after operation is less than 5%.
"Super Mirror Field" Uses Domestic Core Components
A laptop, two plastic stools—one red and one white—plus a lower folding campstool: this is the complete set of equipment in the "mobile office" of heliostat calibration technician Jiang Sirui. After changing roles, Jiang Sirui has been chasing the light since August this year, calibrating the deviation of heliostats at the CSP station of the Green Development Haixi Multi-Energy Complementary Project during the hottest sunshine.
"It's like focusing a camera—calibrating the heliostat's light to the target point." At 11 a.m., after calibrating one mirror, Jiang Sirui began testing. The heliostat with the specified number slowly moved and adjusted to the preset angle, and the reflected sunlight moved from the target point and converged at the designated position.
The receiver that the heliostats aim at is one of the most expensive components of a tower-type CSP station and initially could only rely on imports. At present, Wang Cheng, who serves as the head of OE (Owner's Engineer) for the tower-type CSP station at the CGN Delingha 2-million-kilowatt CSP-Storage Integrated Project (hereinafter referred to as the "CGN Delingha CSP-Storage Project") and is SEPCOIII's project leader in Qinghai, participated throughout the Green Development Haixi Multi-Energy Complementary Project.
Recalling the early days of building CSP stations in China, Wang Cheng sighed that a single receiver tube panel was priced at nearly 12 million yuan abroad, and at that time the first-phase project alone required 24 tube panels. Today, the localization rate of key components is increasing. Wang Cheng introduced that after adopting domestic equipment for the receiver, the price is about one-third that of imported equipment. Another key piece of equipment, the heliostat, also now uses domestic products. The CGN Delingha CSP-Storage Project is equipped with 21,543 domestic heliostats of 30 square meters each, with a mirror field reflection area equivalent to nearly 70 standard football fields.
The CGN Delingha 50-megawatt CSP Demonstration Project located in Delingha City. (Photo by Xinhua News Agency)
At this time in Delingha, a huge silver ocean is taking shape, with the installed heliostats shining brightly in the sunlight. "Previously, the large 138-square-meter mirrors could only be driven hydraulically; now the small 30-square-meter mirrors can be driven directly by green electricity, significantly reducing costs," Wang Cheng said.
The originally extremely costly "super mirror field" has seen a marked cost reduction after key core components achieved domestic production. Jian Zhao, deputy general manager of CGN Solar Delingha Co., Ltd., introduced that at present, the levelized cost of electricity of tower-type CSP stations in Qinghai has dropped to below 0.7 yuan/kWh.
Reporters learned from the Qinghai Provincial Energy Administration that at present, Qinghai has built 210,000 kilowatts of CSP projects and has 800,000 kilowatts under construction. It is expected that 200,000 kilowatts will be newly connected to the grid within the year, at which point CSP installed capacity will exceed 400,000 kilowatts, ranking first in the country.
Shandong People Who Light Up the Receiver Tower
"Walking the Yellow River" reporter Tang Laibu filming at the site of the CGN Delingha 2-million-kilowatt CSP-Storage Integrated Project. (Reported by Dazhong News reporter Zhang Nan)
At around 4 p.m., Golmud, which had been overcast for almost the whole day, gradually cleared up, and the sky began to turn a pure blue.
At this time, the operations and maintenance team at the CSP station's central control center was closely monitoring the DNI (direct normal irradiance) curve on the screen. Wu Chao, director of the operations and maintenance department, based on back-end data and the weather conditions shown by the cameras, gave the instruction to begin preheating. When the DNI value reached 832.78, on the mirror field monitor at the central control center, almost all of the originally blue point map turned red, and the 4,400 heliostats gradually entered working status.
Standing beneath the molten salt tower, one could see the heliostats that had been on standby begin to be activated by area, all aiming at the black receiver atop the molten salt tower, like sunflowers facing the sun. Soon, as the temperature of the receiver gradually rose, the top of the towering molten salt tower emitted a dazzling white light that was impossible to look at directly.
Entering the central control center, the operations and maintenance "brain" of the CSP station, there were four Shandong people on duty that day, including Wu Chao, all from Qingdao Huafeng Weiye Electric Power Technology Engineering Co., Ltd., a subsidiary of SEPCOIII. This year is already Wu Chao's sixth year in Qinghai.
Wang Cheng also came to Qinghai in 2018. Before that, he participated in the construction of the Noor II and III CSP stations in Morocco, the first CSP projects built by a Chinese company overseas on an EPC general contracting basis. "In 2015, we entered the field of global commercial CSP stations and accumulated rich construction and operation experience."
Jian Zhao said that CGN, which was building a tower-type CSP station for the first time, chose SEPCOIII as the project OE precisely because of its rich overseas experience. "After the receiver tower was capped, SEPCOIII gave very good suggestions on the installation of the upper receiver and its coordination with the internal steel structure platform."
The Qaidam Desert Base, included in the national "desert, Gobi, and wasteland" wind and photovoltaic large-scale base layout plan, is a benchmark for Qinghai's efforts to build a highland for the national clean energy industry. As of the end of September this year, Qinghai Province's total installed power capacity was 61.186 million kilowatts. Among this, clean energy installed capacity was 57.295 million kilowatts, accounting for 93.6%, the highest proportion in the country. The former "desert, Gobi, and wasteland" has now become a new oasis of green energy, continuously providing energy for economic development.
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