On July 3, a 30-minute drive from Dunhuang in northwestern China's Gansu province revealed a towering structure rising 260 meters above the arid Gobi Desert. At its peak, a brilliant light shone as if a second sun had emerged, dazzling onlookers from hundreds of meters away.
This site is home to China's first 100-megawatt (MW) molten salt tower solar power plant, built by the Chinese technology company Shouhang High-Tech with an investment of approximately 3 billion yuan (about $664 million). Amid the global challenge of providing substantial electricity due to the rise of artificial intelligence (AI), this facility represents a cutting-edge renewable energy experiment that harnesses solar power around the clock.
The plant spans 780 hectares, equivalent to about 2.36 million square meters, or 1,100 soccer fields. This vast area is lined with over 12,000 heliostats—large mirrors that reflect sunlight toward the tower. Each mirror covers an area of 115 square meters, larger than a typical 1,000-square-foot apartment.
Upon the guide's suggestion, I cautiously placed my hand on one of the mirrors. Contrary to expectations of intense heat, it felt only lukewarm. This is because the mirrors reflect sunlight rather than absorb it.
The heliostats continuously adjust their angles to track the sun's movement, directing sunlight to the top of the 260-meter tower. Here, the heat is used to raise molten salt to temperatures between 540 and 560 degrees Celsius.
The molten salt is then sent to a steam chamber, where it heats water to create steam that drives turbines to generate electricity. After transferring its heat, the molten salt returns to a cooling tank at 300 degrees Celsius, where it is reheated in a continuous cycle. To prevent the molten salt from solidifying below 290 degrees Celsius, the plant maintains it in a liquid state.
The primary advantage of molten salt technology is its ability to store heat. While conventional solar power generation ceases at sunset, molten salt can store heat for up to 11 hours, enabling electricity production even at night. This capability addresses the intermittency often associated with renewable energy.
The Dunhuang plant can generate a maximum of 2.27 gigawatt-hours (GWh) of electricity daily, enough to power approximately 300,000 households in China. A plant representative stated, "The annual planned output is 390 million kilowatt-hours, which will reduce carbon dioxide emissions by about 350,000 tons each year."
Dunhuang is one of the most favorable locations in China for solar energy generation. With an average annual precipitation of just 39.9 millimeters and evaporation reaching 2,486 millimeters, the dry climate allows for 3,246.7 hours of sunshine each year. The area’s low cloud cover and high direct normal irradiance (DNI) make it particularly suitable for concentrating solar power technologies like molten salt.
Along the road leading to the Dunhuang molten salt power plant, rows of black solar panels stretch endlessly. During the day, these panels generate substantial electricity, and at night, the molten salt's stored heat continues to supply power, creating a complementary system between solar and thermal energy.
Recently, China has been rapidly constructing molten salt solar power plants in Gansu, Qinghai, and the Xinjiang Uygur Autonomous Region, focusing on regions with abundant sunlight. This strategy aims to enhance the stability of a renewable energy-centric power system by integrating thermal storage capabilities with the expansion of solar and wind energy.
This approach supports China's solar energy development. Last year, solar power generation in China reached 1.17 million GWh, a 40% increase from the previous year, surpassing wind power generation for the first time at 1.13 million GWh. Solar energy now accounts for 11% of China's total power generation, a significant increase from less than 1% a decade ago. Last year's solar output even exceeded Japan's total electricity production.
China is transforming its northwestern deserts into the world's largest renewable energy base to achieve the dual carbon goals set by President Xi Jinping, aiming for peak carbon emissions by 2030 and carbon neutrality by 2060.
In response to the surging electricity demand in the AI era and the challenge of achieving carbon neutrality, China is accelerating the establishment of a new power system centered on renewable energy, including solar, wind, and molten salt technologies.
* This article has been translated by AI.
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