The International Maritime Organization (IMO) has tightened regulations on emissions of CO2, SOx, NOx, and other substances in order to prevent global warming. In particular, the new SOx emission regulations imposed in January 2020 require ships to use fuel oil with a sulfur concentration of less than 0.5%.
As a result, ships must switch from Heavy Fuel Oil to one of the following four options: use low-sulfur fuel oil, use SOx scrubbers, convert to LNG fuel, or to LPG fuel. Although the initial investment in LNG-powered ships is high, LNG itself is relatively low-priced compared to Heavy Fuel Oil, so it offers significant benefits in terms of long-term cost reduction and also contributes to the reduction of CO2 emissions. As a result, LNG-powered ships have become a popular topic of interest for those involved in the shipping industry.
Building an LNG-Powered Ship Requires a Different Design than Heavy Oil-Fueled Ships
The use of LNG requires a different fuel tank and fueling system to that of a heavy oil-fueled ship, requiring a specialized design for LNG-powered ships.
The location of the fuel tanks and cargo loading space on an LNG-powered ship is a key issue, as the fuel tank volume needed to travel the same distance on an LNG-powered ship is twice as large as that of a conventional heavy oil-fueled ship. This is a disadvantage for cargo ships and ferries. In the design process, therefore, it is necessary to minimize the reduction in cargo loading space while maintaining the space for the LNG fuel tanks.
In addition, the LNG fuel gas supply system must be equipped with a cryogenic pump. This specialized pump pressurizes LNG at -162 degrees Celsius in its liquid state, which is then vaporized into gas to supply the engine.
The entire process of installing LNG fuel tanks and welding and outfitting cryogenic pipes (stainless steel pipes and double wall pipes) also requires specialist skills, that are different from those required for heavy oil-fueled ships.
Design Guidelines to Reduce Construction Costs Are Required
LNG-powered ships are more costly to build than conventional heavy oil-fueled ships. In addition to the installation of large LNG fuel tanks and LNG-related equipment, the design itself is more complex. Although it is possible to retrofit this equipment to existing vessels (LNG-ready ships) as well as new ones, this also requires a high level of technical expertise.
In shipyards that are not accustomed to handling LNG equipment, there are concerns about delays due to design changes and increased workload associated with the outfitting of cryogenic pipes.
In addition, risk assessments must be carried out to ensure the safety of the LNG fuel supply system, and design guidelines to optimize construction costs are also essential, to realize efficient ship building of LNG-powered ships.
- POINTS TO BE ADDRESSED
- Reduction of increased workload at the shipyard
- The fueling system should be provided as a package rather than in parts, to avoid complicated shipbuilding processes and increased costs
- Seeking support, including integration engineering on site
- KEY POINTS TO THE SOLUTIONS
- In order to reduce the workload in shipyards, it is highly desirable to package the fuel supply system and install it as LNG fuel gas supply system (FGSS) modules.
- Support is also required for the construction of the gas handling and peripheral equipment required for LNG fuel conversion, including design, integration engineering, and on-site outfitting.
MHI Offers FGSS Modules, Including LNG Fuel Tanks, as a Packaged Solution
To reduce the construction cost of LNG-powered ships, it is effective to modularize the parts as much as possible and reduce the manufacturing process at the shipyard.
Mitsubishi Shipbuilding Company, an MHI Group shipbuilding and ship engineering company, provides a space-saving and easy-to-maintain FGSS, which modularizes key components such as LNG fuel tanks, gas supply equipment, and control systems.
The FGSS is a fuel supply system developed by Mitsubishi Shipbuilding Company, which is based on its LNG and vaporized gas handling technology and has been developed through the company’s many years of accumulated experience in constructing LNG carriers and other projects.
Mitsubishi Shipbuilding developed the system for shipboard applications after establishing a successful track record of delivering LNG-fueled engine test facilities for land-based applications. The company can provide engineering services for IMO Type C LNG fuel tanks, and engineering support for membrane tanks.
The construction and manufacture of LNG fuel tanks and tank insulation systems for handling ultra-low-temperature LNG requires a high standard of reliability. Mitsubishi Shipbuilding is able to provide high quality products, based on its design and analysis technologies developed over many years, and strict quality control.
MHI has developed cargo handling and propulsion plant control systems (IAS) for LNG carriers, and the group's expertise is being utilized in the FGSS control system. In addition, the company has a number of engineers who are well experienced in gas handling and can customize the control system to meet customer needs.
The FGSS is both modular and compact, allowing more cargo space while reducing construction costs at the shipyard by reducing installation processes. Mitsubishi Shipbuilding will also support the safe operation of each vessel by customizing the control system and other components according to operational needs.
MHI has a wealth of experience in constructing large LNG carriers, and has accumulated a wide range of cryogenic technologies and design expertise in the course of these projects. Based on this experience, MHI will provide plant designs with excellent load-following capability and operational efficiency for a wide range of operating modes.
MHI Will also Support the Shipyard by Providing Integration Engineering for the Application of LNG as a Fuel, and On-Site Support for the Outfitting of Cryogenic Pipes
MHI Group offers comprehensive support to shipyards in the construction of LNG-powered ships, from initial assessment and planning to design, construction, and commissioning, drawing on extensive expertise. In addition, MHI will provide on-site support for the installation of LNG fuel tanks and outfitting of pipes, both of which are particularly difficult tasks in the construction of an LNG-powered ship.
Once an LNG-powered ship goes into service, the company will provide total support services for the vessel, along with after-sales services such as supplying parts and dispatching engineers.
The service offering includes gas handling training and technical support for LNG-powered ships’ crews, and special operations, such as gas-freeing before docking and cool-down after docking.
MHI will add value and improve the competitiveness of ships built at its shipyards. In doing so, the group will contribute to the proliferation of LNG-powered ships, thereby helping to further the development of maritime logistics and reduce the environmental impact of global shipping.