Developments

Technology

The WET-NZ wave energy converter is a ‘point absorber’ device with some special characteristics that enable it to extract energy from passing waves. The device is floating but the majority of it is submerged so that as much of it as possible interacts directly with the wave energy. An object immersed in a wave field is subjected to complex motions – heave (up and down), surge (back and forth) and pitch (a rolling back and forth motion). Most devices extract only a small proportion of the total energy of a passing wave. The WET-NZ device is designed to extract as much energy as possible from more than one type of motion. Click here to see an animation of the device in operation.

Deployments

Quarter-scale Testingwet-nz

Funded by the Foundation for Research, Science and Technology, the project team has undertaken extensive research leading to the fabrication and deployment of two devices in New Zealand waters: a 1/5-scale Proof-of-Concept device and a 1/4-scale prototype . The first device was deployed in both Christchurch and Wellington for short periods over two years from 2006. Its successor was first deployed in November 2009 at Taylor’s Mistake in Christchurch, where it has since spent periods of up to 82 days in open waters. Today it continues to provide the technical team with much valuable research data.

Another 1/4-scale device is due to be built and tested off the coast of Oregon in the USA with funding received in October 2010 from the US Department of Energy. At the same time, WET-NZ will undertake detailed scale modelling at the Northwest National Marine Renewable Energy Centre's wave tanks at Oregon State University.

Half-scale TestingWET-NZ

With funding received from the NZ Government’s Marine Energy Deployment Fund, the research collaboration is also developing a 1/2-scale device. The dimensions of the 1/2-scale device are 17 x 3.5 x 1.5 m with approximately 2 m of the device above sea level. The device, designed to produce 20 kW of power, is to be manufactured at the start of 2011, with its first deployment planned for later in the year at a consented test site.

Test Sites

WET-NZ has received resource consent for two sites for testing its prototype wave energy converters. One is ~4.3 km northeast of the Waitara River estuary in Taranaki, the other is ~2.9 km south of Lyall Bay beach in Wellington. There is the potential at both of these sites to install a submarine cable that can transmit the electricity produced by the device to the shore where it can be connected to a useful load. It is proposed that the local outfall pipes can be used to protect the export cable as it runs through the surf zone and onto the shore. 

Environmental Monitoring

It is important to WET-NZ that the interaction of it’s technology with the coastal marine area is carefully monitored and managed. Robust environmental monitoring plans have been produced for both consented test sites and data collection is due to commence at the start of 2011.  Plans have been produced through consultation with DOC and the Regional councils for both consented test sites and data collection.

Commercialisation

The WET-NZ Programme will continue to develop devices with larger unit generating capacities. WET-NZ is focussed on developing a fully commercial technology to supply 3 potential markets:

  1. Utility-scale, grid-connected multi-unit arrays to supply electricity for network connection

  2. Distributed, smaller-scale devices to supply dedicated and off-grid users

  3. End-uses that include provision of drinking water in remote locations. 

The key aims of the consortium are to:

  • Demonstrate a safe, reliable and low-maintenance wave energy converter that has excellent performance characteristics (e.g., high availability and capacity factor)

  • Demonstrate a cost-competitive and robust technology, in terms of capital costs ($/kW), operating costs ($/kWh) and performance.

© 2010 PPL