Innovative sponge city design boosts resilience for power substations

The science and technology project "Research on Key Technologies for Sponge City Design of Typical Substations", led by the Nanjing Electric Power Design Institute and initiated by the Nanjing Municipal Commission of Urban-Rural Development, has passed an expert review. The project addresses a gap in sponge city design for power infrastructure by providing comprehensive solutions to prevent waterlogging in substations, which are critical urban facilities.

In May, the State Council's "15th Five-Year Plan for Urban Renewal" emphasized enhancing urban resilience through the development of sponge cities. Sponge cities are designed to absorb, store, filter, and reuse rainwater to enhance adaptability to climate change and better manage natural disasters. While the concept has been incorporated into parks and residential areas across China, studies focusing on safety-critical facilities like substations remain limited.

Nanjing's 220kV Raocheng Substation served as a pilot for the project. Substation sites, often constrained by safety requirements, limited space, and complex underground systems, typically rely on hard paving to protect equipment. At Raocheng Substation, which spans 0.88 hectares, with green space accounting for just 5.08 percent of the site, traditional drainage systems cannot handle intense rainfall, which can lead to waterlogging.

To counter these issues, the project developed a "point-line-area" integrated system, combining features like sunken green spaces, permeable paving, rainwater reuse, and building-side trenches. At Raocheng Substation, roads were sloped downward toward a newly-created 420.90-sq-m, 150-mm sunken green space lined with vegetation, which retains and filters rainwater before channeling it into an 86-cubic-meter storage tank. Excess water flows to municipal drains via overflow inlets, while a smart monitoring system tracks discharge and water quality in real time.

The station achieved an annual runoff control rate of 68.51 percent and a non-point source pollution reduction of 48.31 percent, surpassing targets. Similar solutions have been adopted across seven substations in Nanjing. "The sponge city design for substations is not just about preventing waterlogging within the station; it contributes to overall urban resilience. On-site retention and staggered discharge of rainwater not only help protect power grid equipment from heavy rain but also reduce the burden on municipal pipeline networks. In the future, State Grid Nanjing Power Supply Company will continue to promote the integration of sponge city technology with power grid infrastructure, offering a model for the power sector and sharing Nanjing's experience in building highly resilient cities," said Lai Haibin.