Wave energy trial in Tasmania

New technology will provide free power to King Island as it aims to prove low-cost energy generation claims.

Wave Swell Energy, a group developing ocean wave energy generation technology, is carrying out commercial validation trials off Tasmania’s King Island ahead of a potential listing.

The group has built what Wave Swell chief executive Tom Denniss described as “big concrete caverns”, which use the constant back and forth flow of the ocean to generate energy.

“As waves pass into the inside of the cavern the water level rises, this causes pressure on the air, which blows open valves at the top of the unit and turns a uni-directional turbine; as the water recedes it causes negative pressure which closes the valves, creating a cyclical process.”

The air opening and closing the valves turns a turbine, generating a consistent flow of power.

“What sets this apart from other wave generation technology is its lack of moving parts,” Mr Denniss told Fairfax Media.

“It sits just below the water line, it’s like an iceberg, but with only two-thirds underwater.”

The blocks are located in water depths of around 10 metres, and typically found up to 500 metres offshore. They connect to the mainland via undersea cables and provide energy to the onshore grid via a transformer unit.

A single, one-megawatt generation offshore unit weighs about 4500 tonnes. It is built onshore and moved into place using semisubmersible barges.

The group is carrying out commercial validation of its technology on King Island, and has signed an offtake agreement with Hydro Tasmania for an initial 200-kilowatt trial unit, and will operate during 2018 after its initial funding goals are reached.

Denniss said all energy generated will initially be provided to the King Island grid and Hydro Tasmania for free.

Current tests put generation costs at $100 per megawatt hour, or 10¢ a kilowatt hour.