The picture shows the site of the first phase of the construction power supply project of Zhejiang Tonglu Pumped Storage Power Station. [Photo provided to chinadaily.com.cn]

"Close the switch and send power!" Recently, following instruction from staff of the State Grid Hangzhou Power Supply Company, the first-phase of the construction power supply project of Zhejiang Tonglu Pumped Storage Power Station was completed and energized, providing power guarantee for the main construction of the pumped storage power station.

As a national key energy project with a total investment exceeding 10 billion yuan ($1.37 billion), the Zhejiang Tonglu Pumped Storage Power Station project consists mainly of an upper reservoir, lower reservoir, water conveyance system, underground powerhouse cavern group, and ground switch station. With a total installed capacity of 1,400 megawatts, it is designed to install four reversible pump-turbine generator units each with a single-unit capacity of 350,000 kilowatts. Different from traditional hydropower stations that only generate electricity, the pumped storage power station releases water from the upper reservoir to generate and transmit electricity during peak power consumption periods, and uses surplus grid power to pump water from the lower reservoir to the upper reservoir during low-power consumption periods, achieving physical energy storage.

Due to the need to comprehensively consider factors such as natural conditions, geographical location, and power grid demand, the site selection of pumped storage power stations is quite particular, and the entire construction period is relatively long. The Zhejiang Tonglu Pumped Storage Power Station, which officially began construction on Nov 20, 2022, is expected to achieve the first unit's power generation in 2030, with the overall project completed and operational by 2031. The total construction period is approximately nine years. Upon completion, it will provide core functions such as peak shaving, valley filling, and energy storage for the Zhejiang power grid and East China power grid, significantly enhancing the stability of the regional power grid and the consumption capacity of new energy.

As part of the power station project, the construction power supply project is carried out in two phases. The first-phase is led out from the 10 kV line of the 35 kV Luci Substation to the ground switch station of the power station. Approximately 7 kilometers of multi-professional mixed lines are newly built, including 12 steel tower erections with about 2 kilometers of overhead lines; erection of more than 60 utility poles with about 2.5 kilometers of overhead lines; and about 2.5 kilometers of cable lines.

"We are like pioneers, using machetes to clear temporary passages where we can only stand on one foot," said Zhou Yun, a staff member of State Grid Hangzhou Power Supply Company, pointing to the frayed edges on his work uniform snagged by thorns. As the mountainous construction section accounts for up to 80 percent, construction personnel had to carve out work passages in primeval forests densely covered with thorns on steep mountains with a slope of nearly 60 degrees. Sometimes, it took 40 minutes of hiking to reach the work site.

With the successful energization of the first-phase of the construction power supply project, the second-phase will be accelerated and put on the agenda, with other projects advanced in an orderly manner. In the future, with the completion of the Zhejiang Tonglu Pumped Storage Power Station, the group of pumped storage power stations in Zhejiang will significantly enhance the resilience of the regional power grid through functions such as peak regulation and frequency modulation, and accident standby. It is expected to promote the consumption of more than 2 billion kilowatt-hours of clean energy annually, injecting strong momentum into the realization of the "double carbon" goals.