Andreas Späth

Floating solar islands

2014-09-23 09:15

Andreas Wilson-Späth

A few years ago I heard a retired engineer’s reply to a question about how much solar power would be required to supply all of South Africa with electricity. His answer: an area the size of False Bay covered entirely in solar photovoltaic (PV) panels.

To Captonians, this provided a very visual illustration of the scale involved. False Bay is big. But it’s not gigantic. On a clear day you can easily take in the entire bay with the naked eye if you’re in an elevated position (Boyes Drive above Kalk Bay, for instance).

That this is all that’s needed to power our entire country is an amazing thought. Of course the engineer wasn’t suggesting that covering all of False Bay in solar panels is what we should be doing, he was merely using a well known geographical feature to help his audience visualise the dimensions of the area necessary to generate sufficient energy to run the country on sunlight.

Interestingly, this vision is now becoming a reality in a much more literal sense in the form of solar power plants floating on water.

Land in and around urban, commercial and industrial areas – the places where electricity is needed most – tends to be at a premium. While the roofs of buildings are great locations for distributed solar power generation, space for large solar PV power stations can be hard to come by and rather pricey.

The search for alternative locations has led solar developers to mount arrays of panels on floating platforms that can be deployed on inland bodies of water such as dams and reservoirs, or along the coast.

There are additional benefits besides alleviating the space problem:

? The water on which floating solar plants rest can be used to cool the panels, keeping their silicon semiconductors at an optimal operating temperature and increasing their efficiency and lifespan. Being water cooled the panels generate more electricity than their counterparts which are mounted on roofs or on the ground.

? If deployed on freshwater reservoirs or canals, floating solar islands will lower evaporation and reduce algal growth.

The leader in implementing this innovative technology is Japan, a populous country with relatively limited available land but an exceptionally long coastline and a large number of inland water bodies. After Fukushima, floating solar power installations along with other renewable sources of energy are being explored as viable alternatives to climate-changing fossil fuel plants and dangerous nuclear power stations.

Last year, the electronics giant Kyocera, in collaboration with other companies, opened the Kagoshima Nanatsujima Mega Solar Power Plant in southern Japan. While it’s not afloat, this 11.8 hectare project juts out into Kagoshima Bay and its 290 000 solar panels produce enough electricity to supply approximately 22 000 typical Japanese homes. Facilitated by the country’s progressive feed-in tariff system that requires power utilities to purchase 100% of the electricity generated by certain renewable projects, the electricity from the plant is sold to a local power utility and fed into the national grid.

Now, a Kyocera-led consortium is constructing a flotilla of 30 water-born solar plants to be deployed on various reservoirs, each with a capacity of about 2 megawatts (MW), sufficient to power hundreds of households when in operation.

The first two plants will be located on ponds in Kato City near Osaka. By the middle of next year, the project aims to have reached a total generating capacity of around 60 MW.

India is another country that’s expanding its electricity generation into the aquatic realm. A huge 50 MW, 1.27 million square metre floating platform, as well as much smaller 20 kilowatt units, are in development.

There is no reason why this sort of thing shouldn’t work in South Africa as well. We have a long coastline and many dams of varying sizes throughout the country.

I’m not suggesting that we should generate all of our electricity on floating solar pontoons, but this technology does add yet another option to the already very broad pallet of available renewable energy choices. Not only can solar panels be installed on rooftops, on abandoned mine dumps and in disused military bases, but we can float them on dams and along the coast, too.

Now all we need is for someone to tell the government and Eskom, who, in the fog of their coal, shale gas and nuclear addiction, continue to miss the boat when it comes to renewable energy in general, let alone floating solar islands. 

- Andreas is a freelance writer with a PhD in geochemistry. Follow him on Twitter: @Andreas_Spath
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