Tidal projects make headway in Australia and New Zealand  

Tidal Today has a look at the state of play for tidal power projects in Australasia - Tidal projects make headway in Australia and New Zealand.

Overall, the investment climate for renewables, including tidal, is set to improve significantly and tidal resources are being investigated, mostly along Australia’s northern coastline.

Indeed, since the federal government announced its Clean Energy Future programme, a 48MW tidal project originally proposed eight years ago for the north west of Western Australia (WA) is now back on the agenda by Derby Hydro Power, while a number of other projects are also the horizon. These include three large-scale (24-300MW) tidal stream proposals by Tenax to be located at Clarence Strait, near Darwin in the Northern Territory (NT), Port Phillip Heads (Victoria), and Banks Strait (Tasmania).

The company is currently undertaking environmental impact assessments for the projects. The 200MW A$500m (£300m) NT project will use 1MW turbines, while the Port Phillip Heads Tidal Energy Project, if approved, will comprise up to 45 turbines, says Tenax.

Meantime, BioPower Systems is another Australian firm hoping the domestic industry takes off. It’s behind the Biostream tidal turbine, a unit it expects to be deployed for utility-scale power production in future. A pilot installation is located at Flinders Island, Tasmania. [The company is also developing tech for the wave energy sector, with its Biowave device now at pilot demonstration off the coast of Victoria, Australia.]

But, as the company’s CEO, Dr Timothy Finnigan, points out, to avoid causing significant disruption the electricity generated by tidal turbines must be grid-ready. As in the wind energy sector, this makes power conversion technologies a critical component to the tidal industry’s future.

“Ocean energy devices typically oscillate slowly in response to huge forces, and this presents a significant challenge in terms of harnessing the energy to produce electricity," he says. To overcome this obstacle, the company has been working on a suitable system since 2008, thanks in part to funding from the Australian commonwealth government’s Renewable Energy Development Initiative.

Last month, testing of the system – the O-Drive power conversion module – was completed, “successfully delivering stable power to the grid over extended periods with a high level of efficiency."

Developed in collaboration with Bosch Rexroth, CNC Design and Siemens, the self-contained 250kW module plugs into turbines like Biostream. It combines a hydraulic circuit, an electric generator, and complex control algorithms to convert the large forces, and slow motions, inherent to ocean waves and tides into a steady flow of electricity.

“We are pleased with the efficiency of this system, and with the quality of power that is produced," says Finnigan. “The O-Drive not only gears up the motion, but also rectifies it and smoothes it, so that we can produce grid-ready electricity using a standard electric generator."
O-Drive is also designed to be detached from a moored ocean energy system, enabling easy and cost-effective maintenance. Plus, as it also produces high-voltage power (keeping potential transmission losses to a minimum) it allows systems to be installed at substantial distances from shore.

“The system is self-regulating in variable wave or tidal conditions, such that power to the grid is stable and of utility-grade quality," says the firm, noting it is also suitable for use with offshore wind turbines.