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Finland-based technology group Wärtsilä and Japanese machinery industry firm Mitsubishi Heavy Industries Marine Machinery & Equipment (MHI-MME) have signed a memorandum of understanding (MOU) regarding the commercial marketing of a new energy solution for ships.

As explained, the solution combines technologies from both companies to produce greater power generation capacity and higher propeller propulsion for marine vessels.

The new energy solution is expected to be relevant to various types of vessels such as containerships, bulk carriers, car carriers and tankers.

By integrating MHI-MME’s waste heat recovery system and energy saving power generation system (WHRS) with Wärtsilä’s operational control technology for shaft generator systems, the new solution results in more energy efficient ship navigation and an improved Energy Efficiency Design Index (EEDI), the two companies said.

Wärtsilä and MHI-MME claim that the innovation is the combining of a power take off/take in (PTO/PTI) shaft generator system with the WHRS to improve the stability of the WHRS. Depending on the load of the main engine and the ship’s network, the WHRS sometimes produces electrical energy in excess of that needed by the network. Such energy can be utilized via the PTO/PTI generator and at full load, the surplus energy can be used to assist the ship’s drive by being applied directly to the propeller shaft.

At low main engine load, the WHRS can be operated in parallel with a diesel generator set. Parallel operation with a shaft generator via PTO operation is also easily implemented, according to the duo.

The design connects the WHRS generator into the DC link circuit of the PTO/PTI shaft generator rather than directly into the mains. This allows operation of the WHRS at reduced speed to create higher efficiency of the turbine system at part load. In so doing, it avoids the necessity of speed regulation valves, which cause throttle or bypass losses, the companies further explained.

“We are moving forward various energy-saving technologies and can expand our portfolio with this new solution, which we are quite convinced will satisfy present market demands for increasing environmental awareness,” Tomoo Kuzu, Executive Vice President of MHI-MME, commented.