TOKYO (Kyodo) — Wind power infrastructure being installed across Japan has interfered with Self-Defense Force radars for missile detection, prompting the Defense Ministry to request changes in some projects, multiple sources connected to the case said on Saturday.
In some cases, the ministry has also requested that such infrastructure not be installed in areas designated by the government as favorable locations for offshore wind power generation, the sources said.
The government is now considering reviewing the rules governing wind farms.
Although the ministry did not disclose specific cases, more than 10 sites, including some offshore, were subject to project changes or investigations, with some energy operators being asked to revise their plans, the sources said.
However, there is no legislation that allows defensive needs to be used as a reason to prevent the construction of infrastructure on land. This left a government official to comment that the situation could be a “flaw” that harms national security.
According to the ministry, SDF radars emit radio waves that reflect off objects, with the return signal helping to locate those objects. But large wind turbines sometimes block radio waves or create larger reflected signals, making those reflected from objects like missiles and planes harder to detect.
Onshore wind installations are mostly located along coastlines or in mountainous areas, with some of them within detection range of SDF radars, the sources said. The Air Self-Defense Force has warning radars at 28 locations nationwide.
Some wind turbines are over 100 meters tall and could have a particularly big impact on radar, with some known to have hampered Japan Meteorological Agency’s weather observations in the past.
“We are troubled now because we were suddenly told to change the plans we had made according to the rules,” said an official from a wind energy operator.
“The Department of Trade and Industry and the Department of Defense should have coordinated on this.”
Offshore wind power generation has been touted by the Ministry of Economy, Trade and Industry as an ‘asset’ for the expansion of renewables, which Japan more readily embraced after the nuclear disaster of Fukushima in 2011, and designated five sites nationwide as favorable for the exploitation of offshore winds. .
But the Ministry of Defense has asked that certain waters off Aomori prefecture in the northeast be left undisturbed because wind turbines there could interfere with radars used with surface-to-air missiles.
Concerns about North Korea’s missile threats are growing as the country has stepped up ballistic missile testing this year, including one that landed in waters off Aomori in March.
In addition to the missile tests, Chinese and Russian bombers flew over waters near Japan in May, prompting the ASDF to send fighters in response.
“We want to consider reviewing the design of the system to achieve the introduction of wind power while balancing defense capabilities,” a Defense Ministry official said.
According to the Japan Wind Power Association, a total of 2,574 wind turbines had been installed in Japan by the end of 2021.