AKITA -- Wind power generation is being introduced across Japan both onshore and offshore as a pillar in the shift to renewable energy as a leading source of power. But the size of the wind turbines, which can tower as high as some tall buildings, and the rotation of their huge blades can apparently cause disruptions when they stand in the way of communication waves essential in people's lives today.
The city of Katagami in Akita Prefecture, which faces the Sea of Japan and is filled with rice paddies and orchards, serves as a commuter town for the neighboring city of Akita, having a population of about 32,000 people. Along the coast of both cities are 39 wind turbines, each standing about 130 meters tall, stretched out over a distance of about 10 kilometers. The company A-Wind Energy based in the city of Katagami operates the 17 turbines on the northern side, while the Akita Katagami Wind Farm company in the same city operates the 22 turbines on the southern side.
It was around the summer of 2019 that residents living along the coast started saying that their TVs weren't properly receiving signals. The problem has since been resolved, but a resident in his 40s recalls, "At the time, there was a continuation of days where I couldn't see the picture because of the noise on the screen."
Katagami is located on the southern side of the Oga Peninsula, which juts out into the Sea of Japan. The coast curves widely around to the city of Akita to the south, and the TV transmitting station is located more than 20 kilometers away, over the sea. According to experts knowledgeable about reception issues, the problem reported in Katagami is believed to have been caused by interference from the wind turbines and the rise and fall of the tides.
Radio waves have similar properties to light, moving in straight lines, and they are reflected off the ocean and other surfaces they hit. Experts say that when transmitting and receiving points are separated by a body of water, the radio waves that travel straight and the ones that reflect off the water interfere with each other. This causes a disturbance that weakens the waves by the time they reach their destination. Along the coast of Akita Prefecture, the difference between the high and low tides is 20 to 30 centimeters, so radio waves are affected by changes in the height of the water surface. In addition to the effects of topography and sea level changes, when there are turbines between the transmission and receiving points, the waves can be blocked by the turbine poles or become disrupted when they pass through the path of the blades.
However, reception problems can be resolved by changing the height of antennas or installing devices that amplify weak signals. In the city of Katagami and other areas there have been about 2,000 claims of reception trouble. In those cases, providers covered the cost of fixing them. In Europe and other areas where the introduction of wind power has progressed, cable television is mainstream, so there are apparently few reports of reception problems caused by turbines.
Is it also possible that offshore winds turbines could also disrupt reception signals? The areas off the coasts of the cities of Oga, Katagami and Akita have been designated as promotion zones for offshore wind power under Japan's law on promoting the utilization of sea areas for the development of renewable energy power generation facilities, and in the future, the government plans to hold bids to select offshore wind power generation operators. The offshore turbines are expected to be bigger than those already in operation onshore, but experts say that the same problems could indeed occur with offshore wind power.
It is not only television signals that turbines can disrupt. In August 2020, a weather radar on Mount Yahiko which straddles the village of Yahiko and the city of Nagaoka in Niigata Prefecture identified wind turbines along the coast of Akita Prefecture as "rain clouds" and a heavy rain warning was issued, but no rain fell at all. Objects that don't move, like buildings, are rarely mistakenly detected as rain clouds, but turbine blades are recognized as moving objects, causing waves to be mistakenly perceived as having reflected off rain clouds, officials say.
As it stands, it seems that there are a number of problems that need to be overcome before this form of renewable energy can progress with wind in its sails.
(Japanese original by Marika Inomori, Akita Bureau)