A demonstration test of the Japanese Hz Navi system, designed to produce energy-saving effects by lowering the frequency of the generator according to optimal specifications, has been concluded over a 12-month period on the NYK-operated bulk carrier ‘White Princess’.
The companies involved were NYK Line, MTI, Oshima Shipbuilding, Terasaki Electric and Daihatsu Diesel. In the demonstration test, fuel consumption was measured and a safety evaluation was conducted with the Hz Navi mode (about 57Hz) activated, and an energy-saving effect of approximately 10% was confirmed for the generator. No abnormalities were observed during the demonstration test, and it was confirmed that the vessel could be safely navigated.
Current generator frequencies are set so that onboard equipment such as pumps and motors, which operate in conjunction with the power supply frequency, can perform adequately even under the worst possible conditions, and operating at the normal frequency during normal navigation consumes extra power. Therefore, there was a need to develop a system that could reduce fuel consumption and quantity by lowering the frequency of generators to best match optimal specifications.
The Hz Navi system allows generator frequencies to be adjusted according to shipboard conditions within the range specified by ship classification rules, thereby reducing the fuel consumption and emissions of generators. The system utilises a technology jointly patented by NYK and Tsuneishi Shipbuilding known as generator frequency control technology (Patent Number JP6238600), which allows the generator frequency to be switched between the regular frequency and a lower energy-saving frequency.
Image: ‘White Princess’ took part in the Hz Navi trials (source: NYK)
