- The second-generation bubble lubrication system significantly reduces energy consumption of commercial vessels by about 5%.
- The system reduces frictional resistance by injecting compressed air to create bubbles.
- The new version improves the air supply structure and adds automated control features.
- The system is compatible with various commercial vessels and propulsion technologies, offering expansion potential.
Chinese engineers have applied drag reduction principles related to high-speed underwater munitions to improve the energy efficiency of commercial vessels. Reports indicate that a recently constructed 50,000-ton product and chemical tanker has been equipped with a second-generation bubble lubrication system, which achieved approximately a 5% reduction in net energy consumption during a five-month operational trial. The system was developed by the Shanghai Maritime Design and Research Institute, which injects compressed air at the bottom of the hull to create a layer of bubbles, reducing friction with the surrounding water. The tanker is now in service, and results show that this technology could help shipping companies reduce fuel consumption without altering the vessel's primary propulsion system.
Additionally, the institute estimates that for tankers of this size, a 5% reduction could save approximately one ton of fuel per day.
Principle of Bubble Lubrication Technology
Bubble lubrication technology aims to reduce the contact between objects and surrounding water. For example, supercavitating torpedoes operate within a gas-filled cavity, significantly reducing their contact with water, allowing them to achieve extremely high underwater speeds. The commercial shipping system employs a different implementation of this principle. According to the South China Morning Post, the system does not create a large cavity around fast-moving munitions but continuously injects compressed air at the bottom of the hull to form a layer of microbubbles between the hull and seawater. This alters the water flow near the vessel's surface, creating a gas-liquid mixture that reduces frictional resistance.
With reduced resistance, the propulsion power required to maintain the vessel's speed also decreases. The overall efficiency improvement depends on the balance between the power saved by reducing hull friction and the electricity consumed by the compressor providing the air. The reported 5% net energy consumption savings take this additional energy demand into account, although the institute has not provided a detailed breakdown of the trial results.
System Upgrades and Automation
The second-generation bubble lubrication system was improved based on an early version tested on an 1,800 TEU feeder container ship in April 2022. Development of the upgraded system began the following month, with engineers aiming to address the earlier design's reliance on manual operation. The new version includes an improved air supply structure designed to reduce the power consumption of the compressor and adds automated control and monitoring features. Its intelligent control system adjusts the amount of air supplied to the bottom of the hull based on the vessel's speed and draft. The digital operation support system can also monitor and analyze energy efficiency in real-time.
These features aim to make the technology easier to operate under changing navigation conditions while reducing the energy required to generate bubbles. The system is designed to be compatible with different types of commercial vessels and propulsion technologies. According to the institute, it is compatible with vessels powered by LNG, electricity, methanol, and ammonia. These new developments provide additional groundwork for its deployment on commercial vessels, but broader adoption will depend on performance across different hull designs, operating conditions, and shipping routes.
Commercial Potential and Challenges of the Bubble Lubrication System
The development of the bubble lubrication system marks a significant advancement in the shipping industry's efforts to enhance energy efficiency. By reducing friction, this technology not only lowers fuel consumption but also improves operational efficiency. With the release of the new version, the system's automation and intelligent control features make it more adaptable to varying navigation conditions. However, widespread application will still need to consider the adaptability to different hull designs and operating environments, which will affect its adoption rate in commercial shipping.