Pioneering ship-grid energy project sets sail

As summer brings peak electricity demand, energy storage has emerged as a critical tool for balancing grid loads, attracting widespread attention. In Lianyungang, Jiangsu province, a pioneering project has achieved bidirectional ship-grid interaction, turning electric vessels into "mobile power banks" at the port. The innovation creates an advanced maritime source-grid-load-storage application scenario for China's new-type power system.

Compared with vehicle-to-grid applications, ship-grid interaction presents greater technical challenges, particularly in terms of power ratings and safety requirements. Zhu Guangqing, deputy director of the marketing department at the Lianyungang branch of State Grid Jiangsu Electric Power, said the company had worked with research institutions to develop a coordination device that uses grid-forming control algorithms.

"The equipment enables seamless transitions between power-consuming and power-supplying modes once electric tugboats are docked," Zhu said. He added that once high-voltage direct-current, high-power discharge technology matures, a fully electric tugboat could feed more than 5,000 kilowatt-hours of electricity back into the grid within one to three hours. That is equivalent to the combined discharge capacity of 100 standard electric vehicles.

Four all-electric tugboats are currently operational at Port of Lianyungang, forming a 20,000-kWh mobile energy storage cluster capable of supporting five large quay cranes running simultaneously.

The tugboats charge during offpeak hours and sell surplus energy back to the grid during periods of peak demand, reducing the port's energy costs, strengthening grid resilience and delivering both economic and environmental benefits.

The port has established a green microgrid integrated into its operations to ensure the safe and efficient use of electrified facilities.

According to Zhuang Jun, an expert at the Shanghai branch of the China Electric Power Research Institute, the large-scale adoption of ship-grid interaction will facilitate the development of an intelligent shipport-grid energy ecosystem.

The Lianyungang project provides a model for domestic ports pursuing the green transition of the shipping sector. It enables intelligent dispatch, automated settlement and credit management for ship-borne energy storage while fostering new business models in the power sector.