Ships entering Zhangjiagang port in East China's Jiangsu province now can turn off their combustion engines for the duration of their stopover and instead use electricity from the local grid for their power supply.

"In the past, the diesel engines were still running after the ships stopped moving, making a lot of noise and giving off heavy black smoke," said Fan Guanghu, a ship's captain.

But things have changed now. Fan's ship recently docked at Zhangjiagang Port Group's berth No 13, and as soon as the crew shut down the diesel engine, electricians came to help them connect the cable to the onshore power box to the ship. "Now, with the use of electricity from an onshore grid connection, less pollution is produced and the environment is much better," Fan said.

Shore power has been promoted by Zhangjiagang over the years as an important step to make its port greener and more environment-friendly. The city has continued to improve its port infrastructure to support the new practice.

Last year, 85 percent of Zhangjiagang's wharves offered the service, and by  the end of August this year, all wharves in the city had adopted shore power.

Zhangjiagang Port has therefore become the first port in the province that can supply high-voltage electricity to sea vessels as well as container liners, inland vessels and other types of vessels.

According to Fan, diesel power generation costs about 300 yuan ($44) for 12 hours but that cost can be saved now thanks to the free power provided by the wharf for small and medium-sized ships.

To roll out the measure smoothly, the Zhangjiagang maritime bureau teamed up with transport, power supply and other departments to improve the shore power facilities, strengthen equipment maintenance and troubleshoot potential problems. Wharf units are also starting to provide free shore power to inland vessels for a certain period of time.