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Alexandra in Tech Talk,

The island nation wants to replace nuclear energy with renewable power!

The 2011 earthquake and tsunami crippled Japan’s nuclear industry, which supplied a third of the country’s electricity. Nowadays Japan looks to move on from the Fukushima disaster and meet the energy needs of its 127m people without relying on nuclear power. Before the incident around 30% of the country’s power was generated from nuclear, with plans to push this to 40%. But Fukushima destroyed public confidence in nuclear power, and with earthquakes in regions containing reactors highly likely, Japan is now looking for alternatives.

Solar power is an obvious solution for relatively resource-poor nations. It is clean, cost-competitive, has no restrictions on where it can be used and has the capability to make up for the energy shortfall. A small fact that solar researchers love to trot out is that enough sunlight falls on the earth’s landmass around every 40 minutes to power the planet for a year. To put this another way, if we covered a fraction of the Sahara desert in solar panels we could power the world many times over.

In places like Japan where space is limited, more inventive solutions are required. This is the principle reason behind the decision to move their solar power generation offshore. While the land is highly congested, and therefore expensive, the sea is largely unused. It therefore makes a good degree of sense to use this space for floating power plants.

Solar power is booming in Japan; the nation doubled its solar power capacity within two years of the 2011 Fukushima nuclear disaster, and is now a world leader along with China and the US. While physicists continue to work on floating nuclear power plant designs, which would use ocean water to cool the reactor in the event of an emergency, in the meantime floating solar power plants are having a moment in the sun.

Two floating solar power plants capable of providing electricity for 1,000 homes have been completed in Japan. The plant's 11,250 modules are expected to generate 3,300 megawatt hours (MWh) every year.

According to Kyocera, besides being typhoon-proof (due to their sturdy, high-density polyethylene and array design) floating solar plants are superior to their land-based equivalents because of the cooling effect of the water, which allows them to function more efficiently. Reservoirs are also an ideal location because the panels produce shade, which reduces water evaporation and promotes algae growth. A report by Korea Water Resources Corporation found that the lower temperatures of the floating modules mean they are 11 percent more efficient than land-based equivalents.

Floating solar plants are not as exotic as they may sound. Some are starting to appear in the UK, while larger scale projects are also planned in California's wine country. Around 25 percent of Sonoma county's vineyards have ponds (to protect against flooding), and these are already proving to be ideal plant locations. In neighboring Napa Valley, Far Niente Winery already has around 1,000 modules fixed to a pontoon on its land and others are due to follow suit. The floating plants help sustain the business, with excess power being fed back into the national grid.

Solar islands could certainly be a solution for other countries where space is an issue – it’s possible that one day a significant portion of Europe’s power could be generated by giant solar pontoons in the ocean. The technology exists and the engineering challenges are nothing that can’t be overcome.