Chongqing - A cruise ship glides away from Chaotianmen Port in Chongqing. On deck, visitors photograph the city's waterfront, while onboard equipment works to reduce emissions from the vessel's engines.

Chongqing's illuminated skyline stretches along the Yangtze River at night. (Photo/Chongqing Ecology and Environment Bureau)

The Changhang Chaotianmen is part of a pilot program launched in 2022 to tackle air pollution from inland passenger vessels. The project reflects Chongqing's broader efforts to reduce shipping emissions and protect the Yangtze River, China's longest waterway.

A worker inspects a low-temperature selective catalytic reduction (SCR) exhaust treatment system aboard a sightseeing vessel in Chongqing. (Photo/Chen Yu)

The pilot initially covered seven sightseeing passenger ships in Yuzhong District. Authorities installed selective catalytic reduction (SCR) exhaust treatment systems, which use a chemical reducing agent and a catalyst to convert nitrogen oxides (NOx) into nitrogen and water vapor.

He Zhenbo, a city cruise operations manager, said the equipment was adapted to the operating conditions and limited installation space aboard inland vessels.

The project also introduced a portable emissions measurement system to monitor exhaust under actual operating conditions.

The results showed NOx emissions from individual engine units were reduced by as much as 95%. After treatment, NOx concentrations were about 20% below the limit set by the International Maritime Organization's (IMO) Tier III standard, the strictest level cited in the project information.

From exhaust treatment to cleaner energy

While retrofitting existing vessels addresses pollution from the current fleet, Chongqing is also incorporating cleaner energy into newly built ships.

The Victoria Isabella, which began operating in September 2025, uses a hybrid system combining solar power, energy storage and diesel generation.

The Victoria Isabella, equipped with a hybrid solar, energy storage and diesel power system, operates from Chaotianmen Port in Chongqing. (Photo/Yuzhong District Ecology and Environment Bureau)

Solar panels cover much of its roof. The system generates more than 400,000 kilowatt-hours of electricity annually and has reduced its reliance on shore-based electricity by more than 30%, according to local environmental authorities. Its cumulative carbon reductions are equivalent to the amount absorbed by planting 1.25 million trees.

The city is also upgrading port infrastructure to support cleaner vessel operations. At several berths in the Chaotianmen area, standardized shore-power facilities allow ships to connect to electricity while docked rather than running their engines.

A dual-power floating platform provides shore-side electricity for vessels docked at Chaotianmen Port in Chongqing. (Photo/Yuzhong District Ecology and Environment Bureau)

To address the Yangtze's water-level fluctuations, which can reach 30 meters, authorities introduced dual-power floating platforms and high-voltage power supply technology. An intelligent system enables vessels to connect to shore power within 15 minutes of docking.

More than 98% of Chongqing's tourist passenger vessels now use shore power, according to the local environmental authorities.

Regulations strengthen pollution controls

Equipment upgrades are accompanied by stricter rules governing wastewater and other ship-generated pollutants.

The Chongqing Regulations on the Prevention and Control of Ship Pollution, which took effect in 2025, introduced a system requiring ships to store wastewater onboard and transfer it ashore for treatment.

Vessels must dismantle, permanently block, or seal overboard wastewater discharge pipes. All tourist passenger vessels and Yangtze and Jialing River sightseeing boats in Yuzhong District have completed the required modifications, achieving zero direct wastewater discharge.

The measures form part of broader environmental improvements along the Chongqing section of the Yangtze. During China's 14th Five-Year Plan period (2021-2025), shore-power substitution reduced fuel consumption by 12,000 tonnes. Water quality at all national monitoring sections along the Chongqing reach of the river has maintained good or excellent ratings.

Chongqing's vessel zero-emission management model has also been promoted across the Yangtze River basin. The municipality is working with Hubei on coordinated environmental legislation and with Sichuan to improve connectivity between port shore-power systems.

For Chongqing, the effort links cleaner shipping with the continued development of river tourism and inland waterways. The goal is to reduce pollution from vessels while maintaining the economic and transport functions of the Yangtze.