Looking to the ocean for energy

A letter to the editor of a Christchurch newspaper two-and-a-half years ago spurred the merging of two minds to come up with a plan to meet the country’s power needs.

Scientist David Beach of Applied Physics Limited in Christchurch, wrote to the newspaper about the potential of tidal power generation. Engineer Chris Bathurst, who also runs his own business in Christchurch – Solvent Rescue Limited – saw the letter and gave David a call.

The pair have since been working on a plan which they say in future has the potential to meet the country’s electricity needs, and were in Ashburton last night to talk to Mid Canterbury Forest and Bird members.

Tidal energy is an untapped global resource, and just recently an experimental tidal power station was created off the coast of the Orkney Islands near Scotland.

Mr Bathurst and Mr Beach are proposing to set up a tidal power station in the Cook Strait, which they say has the best waters for such a project in the Southern Hemisphere. While most straits are shallow and lack potential, the Cook Strait is deep and could easily accommodate the tidal turbines which a tidal power station would require.

Over a 10km by 10km area, the pair propose to have 6600 tidal turbine units, at a depth of from 20 to 50m. Each unit has two propeller sweeps, 20m in diameter, or four propellers 10m long each. There would be 66 units per square kilometre.

“You would have to be a fish to see it,” Mr Bathurst said.

The advantage with tidal power is that it is an entirely predictable source of power, unlike wind power which relies on when the wind blows.

“It is driven by the sun and the moon so it’s absolutely predictable and it’s a huge resource,” Mr Bathurst said.

The pair have created their own company, Neptune Power Limited, and plan to have in two years time the first prototype in the water at Cook Strait. They said they will need to go through a long process to be able to install the power station, such as working under the Resource Management Act, Foreshore and Seabed legislation, local council by laws and consulting with fishing industry representatives.

“If we have done our work and we don’t have any opposition then we don’t think there will be too many barriers to getting the thing financed up.”

They said the proposal had not cost them money to date, only plenty of their time, but at some stage they would need close to $1 million for research and development of the site, but do not expect this will be difficult to generate, with there sure to be plenty of investor interest.

Tidal power has peaks and troughs throughout the day as currents pulled by the forces of the sun and the moon ebb and flow. An advantage is that all the power is generated from one site so cables can come to the one area, minimising transition losses.

The power station they are proposing could generate an average of 7000 megawatts of power, and currently New Zealand’s electricity it generates from all its sources is 7000 megawatts.