Japan intends to double its current inter-regional power grid capacity of 24 GW by adding 23 GW of new transmission lines to accelerate the development of wind capacity in Hokkaido, Honshu and Kyushu. Indeed, the country plan to connect Hokkaido and Tokyo via undersea cable with a capacity of 8 to 12 GW, to link up Hokkaido and Honshu via undersea cable, and to couple the northern area of Tohoku and greater Tokyo via landlines. In addition, the transmission capacity between Honshu and Kyushu would be expanded. Construction may start in 2022 at the earliest. The projects are yet to be finalised and need to secure land before proceeding.
The Japanese electricity market is segmented into regional monopolies, resulting in low interregional grid usage (only 8.5% of Japan’s total electricity production in fiscal year 2019). Japans intends to generate about 10% of its total electricity output from offshore wind plants, which would be predominantly located in Hokkaido, Honshu and Kyushu. New transmission infrastructures are needed to transport electricity from these regions to urban areas such as Tokyo and Osaka.