A Demonstration of the Performance of S2G (Ship to Grid) System in a Detached Fishing Island

摘要

We have demonstrated a newly developed S2G two-way electricity transportation system (from ship to grid and from grid to ship) to prove the effective use of renewable energy for ship propulsion and successful reduction of CO_2 emission. This research is conducted under the research program of "Empirical study of the independence distribution energy system technology based on DC technology in a detached island and a fishing village" financed by the Ministry of Environment of Japan subsidy 2014-2016. In this paper, the following results are shown. To conduct the research, a plug-in hybrid electric fishing boat (50 kW electric motor, 140 kW diesel engine with a 10kW generator and a 20 kWh Li-ion battery system) was prepared, named PHEB-2, developed under collaboration research between Osaka City University and the Kansai Electric Power Co., Inc. One electric vehicle (total battery of 20 kWh) was also used to transport the electric energy obtained by the solar cell power line (the grid) with the Li-ion 46 kWh battery system to the boat as the normal G2S operation. The PHEB-2 can also generate electricity so that the electric energy can be supplied from the boat to the grid via the electric vehicle when natural disasters happen. It is proved that the newly developed S2G system worked successfully using high efficiency DC-DC converters. It is shown that the transportation efficiency of the S2G system from the ship to the grid and vice versa was kept at 90%. It is also quantitatively shown that the plug-in hybrid boat (PHEB) provides an outstanding CO_2 reduction of more than 80% compared with the simple diesel engine operation when a professional fixed position fishing pattern at the research island (Nushima, Hyogo, Japan) was conducted. The population of Nushima is 500 and the number of fishing boats is 162. The remarkable reduction of oil consumption is due to the high efficiency of the electric motor and the good performance of the idling stop function of the electric motor propulsion during fixed fishing operation.