Visit to Plant

Dioxide-contaminated Land Revived as Solar Power Plant

2014/06/30 10:53
Kiyotaka Nakanishi, Nikkei BP CleanTech Institute
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Hashimoto City is situated in the northernmost part of Wakayama Prefecture and adjoins Osaka Prefecture to the north and Nara Prefecture to the east. "Wakayama Hashimoto Solar Way," a solar power plant that construction consulting company Kokusai Kogyo Co Ltd (Chiyoda-ku, Tokyo) has developed in Hashimoto City, was completed in April this year (Fig. 1).

The plant, where 2,832 solar panels are arrayed across the 12,500m2 area of land, has an output of 708kW. The solar panels are the product of Toshiba Corp (SunPower Corp of the US), and the PV inverters are the product of Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC).

Wakayama Prefecture enjoys so much sunshine that it can be counted within the top ten prefectures that boast the highest annual amount of sunshine across Japan. It is, however, largely mountain forests with a small amount of large flatland.

The site of "Wakayama Hashimoto Solar Way" is also not completely large flatland. Elongated north-south, approximately one-third of the land on the south side slopes. The central area of the power plant site is strangely left vacant (Fig. 2). There is a reason for this. Buried under the area where no solar panels are set up is a gigantic concrete container that seals soil contaminated by dioxide.

The site was polluted by dioxide, which was once a major social issue. The site had originally been owned by an industrial waste disposer, but the prefecture took over the land from the disposer for ¥100 million (approx US$985,707) in 2003 to accelerate its pollution control measures. The land was left idle for ten years even after being decontaminated. In July 2013, Wakayama Prefecture made a public offering of the land's rental use as a solar power generation project site. Kokusai Kogyo was chosen as the power producer.

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