Indonesia is a nation of over 10,000 islands, so supplying the entire country with electricity is a huge challenge.
Over a million people are not connected to the power grid at all.
“Those people who don’t have electricity live on remote islands, so in this situation it’s hard to connect a cable to them and it’s hard to install other expensive solutions like wind turbines,” says Luofeng Huang, a lecturer in mechanical engineering at Cranfield University.
Solar energy is one option for providing energy to these islands. It has become much cheaper in recent decades – the International Energy Agency (IEA) says it is becoming the cheapest option for new power plants.
But solar farms take up a lot of space – space that could be better used for housing, agriculture and business.
That’s why scientists and engineers are working on ways to install solar panels on the surface of the ocean, providing energy to the inhabitants of the nearby land.
“Floating solar power is very convenient because you can just put it on the water, and if you need more electricity, you can put more solar panels on it,” says Huang.
Floating solar power is already used in many places around the world, but on lakes rather than at sea.
The reason is obvious: waves can easily flood and damage solar panels.
However, research and testing is underway to find ways to keep solar panels intact and work in choppy water.
For example, the Dutch-Norwegian company SolarDuck is working with the German energy company RWE to build a floating solar power plant at a wind farm in the North Sea.
The company says it will be the largest offshore floating solar power plant in the world, capable of powering several hundred homes.
The solar panels will be placed on platforms raised several meters above the surface of the ocean. The power plant, which is scheduled to become operational in 2026, will use the wind farm’s existing wiring to transfer electricity back to shore.
Meanwhile, Ocean Sun has developed a floating platform where solar panels rest on a base that flexes as waves pass underneath.
“This has the effect of dampening the waves and preventing them from breaking up,” says founder and CEO of Borge Bjorneklett.
He says that because the panels lie completely flat, the forces acting on them decrease. The proximity of sea water also cools the cells, which improves their efficiency.
Both Ocean Sun and SolarDuck are considering placing solar farms next to wind turbines, which will smooth the flow of electricity when the wind is not blowing.
Mr. Huang says both approaches have weaknesses. By floating the panels above the sea surface, the SolarDuck system can be a more expensive solution.
“If you lift it, you need a very strong support, so it will just cost too much money,” he says.
When offered a chance to answer it, SolarDuck did not respond.
As for the Ocean Sun system, Mr. Huang is not convinced that this approach will sufficiently protect the panels from wave damage.
Mr Bjorneklett admits that his company’s system may not be suitable for the North Sea with waves as long as 30 feet (9 m). But he says the system survived Category 4 typhoons during a tank test.
“We find coastal locations, with milder sea states, to be more attractive,” he says.
Mr Huang’s team at Cranfield University is working on an alternative offshore solar power plant that he believes will be robust and cheap.
Together with academic and commercial partners in Indonesia, they hope to set up a demonstration system in the Indian Ocean in 12 months.
Dubbed Solar2Wave, it will have a floating breakwater in front of the solar panels, which Huang says will reduce wave heights by about 90%.
The reduced waves then travel through a buffer zone – a small enclosed area of water – which further reduces the power of the wave before it hits the solar panels themselves.
Maintaining a cheap breakwater will be key: “Any damage will be to the part of the breakwater that is cheap and very easy to replace and maintain,” says Huang.
While the cost of installing and maintaining any ocean solar farm will be high, in many cases such farms will be the only way to supply renewable energy in some densely populated parts of the world.
“In Singapore, for example, the cost of land is very high, and they have already used most of their roof space,” says Bjorneklett.
“If they can use the ocean surface outside of Singapore, that’s actually the only way to provide affordable renewable energy, and there’s a similar situation in other large parts of Southeast Asia as well.”
Photovoltaic farms could even be located far offshore, where they could serve as refueling points for electric ships.
More business technologies:
It definitely has a lot of potential,” says Luofeng Huang of Cranfield. “Everyone wants to solve it, so we work quite hard and it’s like a competition to see who can bring in the first successful project.”