Japan's biggest floating solar plant sparks into life

A floating solar mega-power plant, with the largest production capacity of its type in Japan, started operating March 5.

"[Floating solar power plants] operate at lower temperatures than conventional solar power plants, so they are more efficient," K Srinivas Reddy, a professor of mechanical engineering at the Indian Institute of Technology Madras in Chennai, India, tells The National.

Constructed on the Yamakura Dam in Ichihara, Chiba Prefecture, the plant is projected to generate an estimated 16,170 megawatt hours [MWh] per year - enough electricity to power approximately 4,970 typical households - while offsetting about 8,170 tonnes of CO2 emissions annually, the company that developed the plant says.

The plant has been built by Tokyo-based Kyocera TCL Solar, a joint venture between Kyocera Corporation and financial services company Tokyo Century Corporation, which provided the financing.

Based in the city of Kyoto, Japan's ancient former capital, Kyocera Corporation manufactures industrial ceramics, solar power generating systems, telecommunications equipment, office document imaging equipment, electronic components, semiconductor packages, cutting tools, and components for medical and dental implant systems.

The plant uses the Hydrelio floating solar technology developed by France-based Ciel et Terre, which has been developing large-scale solar power plants since 2006. The company launched its Hydrelio system in 2011, and that market became its sole focus two years later.

Hydrelio floating platforms provide the support structures for solar panels that are installed on large water bodies such as lakes, reservoirs, canals and ponds.

The Yamakura Dam reservoir, on which the Japanese plant has been built, provides industrial-use water to companies in the Keiyo Rinkai Industrial Zone on the north-eastern coast of Tokyo Bay that covers eight cities in Chiba Prefecture. The dam is sourced by the Yoro River and is the first reservoir for industrial water services in the prefecture, managed by the Chiba Prefectural Waterworks Bureau.

Like the US with its 50 states, Japan is divided into 47 prefectures. The capital, Tokyo, is itself not a city but a prefecture.

Built on 18 hectares, or approximately one-third of the Yamakura Dam reservoir surface, and 1.5 hectares on land, the plant has 50,904 solar panels, with an estimated maximum output of 13.7 megawatts at any one time.

Floating photovoltaics are a way of opening up new sites to solar power generation, Bloomberg New Energy Finance [BNEF] head of solar analysis Jenny Chase says. Combined with bifacial module technology, which captures energy reflected off the water's surface, they have advantages over traditional panels, Ms Chase says.

"They also reduce evaporation from the reservoirs, and where the water is a hydroelectric dam lake, can make use of existing transmission infrastructure. Power production may be anti-correlated with hydroelectric production, which is useful."

However, Ms Chase says floating solar power plants are not especially different from conventional ones, but in Japan with a generous power purchase agreement and no land, the economics work. "The capacity factor of 13.5 per cent doesn't suggest the developer expects amazing benefits from cooling or reflection on to bifacial modules," Ms Chase says.

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Kyocera will not disclose the project's construction budget or the investment required to build the facility, company spokeswoman Natsuki Doi tells The National.  However, the construction cost of a floating solar power plant is about the same as a land-mounted type although civil engineering work is unnecessary, and it is easier to set up the floating mounts with solar modules, Ms Doi says.

"Therefore, the total cost of these two types are almost equal, although the mounts utilised for the floating type are more expensive than the land-mounted type," she says.

Harold Meurisse, international business developer at Ciel et Terre, told Bloomberg that a direct price comparison between floating and rooftop or ground-mounted systems is not indicative of reality. “It is a totally different kind of project."

But he said, “in some countries, we are already more competitive than ground-mounted systems." He added that this was the case in particular “where land is expensive and rare" or where "land [requires] a lot of civil engineering work like excavation, deforestation or seismic foundation [to house land-based solar]; or land where it is costly to dismantle if you have concrete foundations or you need to do grass maintenance.”

The biggest such facility in the world is being built in China's Three Gorges area. When completed in May of this year, the $151 million installation will generate 150 megawatts of electrical power. The new solar power plant will be operated by the Three Gorges Group, an instrument of the Chinese government.

back in Japan, since all energy generated from the Yamakura floating solar power plant will be sold directly to electricity companies, there is no plan to store power in battery systems. "We plan to apply a price of ¥32 [Dh1.1, before tax] per 1 kilowatt-hour, but we do not disclose the annual revenue of electricity sold," Ms Doi says.

However, media reported all the electricity generated at the plant will be sold to Tokyo Electric Power for an estimated ¥450m a year.

As there is further potential in Japan with its many reservoirs suitable for constructing floating power plants, Kyocera would like to proactively promote further development in the Japanese market, Ms Doi says.

Similar smaller plants Kyocera constructed that are already selling energy include a 2.5MW one in the city of Suzuka in Mie Prefecture, and a 1.9MW one at Shimoyama Pond in the city of Bizen, Okayama Prefecture. An 8.9MW plant is under construction in the city of Okayama City, the capital of the prefecture of the same name, Ms Doi says.

"We are considering developing similar projects overseas, mainly in Asia," she says.

For its part, Ciel et Terre Japan has built such plants in the cities of Awa in Tokushima Prefecture [4MW] and Tenri in Nara Prefecture [1MW]. The company is presently building a 5MW plant in the city of Takamatsu in Kagawa Prefecture, and a 2MW one in the city of Tsu, Mie Prefecture, Ciel et Terre Japan representative director Hajime Mori tells The National.

Mainly in western Japan, Ciel et Terre Japan is planning to build 30MW plants in the prefectures of Hyogo, Osaka, Okayama and Hiroshima, among other regions in the country. The company has set a goal to build a 100MW floating solar photovoltaic power plant by 2020, Mr Mori says.

"Based on our achievements in Japan, Ciel et Terre's head office in France is working on developing solar photovoltaic power projects in the US, Brazil, China, Taiwan, South Korea and South East Asia," he says.

Floating solar plants can be implemented on any water body, Mr Reddy says. ”So these plant may be very successful in other countries as well."

Ms Chase says there are "a bunch" of such plants in China and South Korea already. "They have invented 'boats' there too."