Development of Marine Energy in New Zealand

In 2007, the Commission initiated the “Transmission to Enable Renewables” (TTER) project which looked into the location and capacity of different types of renewable energy in New Zealand. This work was used to develop the 2008 GPAs and focused on wind, hydro and geothermal as these are the main types of renewable energy which are currently mature in New Zealand.

The Commission considers that it is important to look further into the future and assess other potential sources of energy. As marine energy is on the rise worldwide and the pace of the domestic marine energy activity has picked up over the last few years, it seems reasonable to look at this particular technology. In early 2008, Power Projects Ltd was contracted to provide advice on potential marine energy (wave and tidal) schemes including location, capacity and energy production.

• Final report on Marine energy pdf [7432 KB]

The report suggests that energy extracted from wave looks more promising in New Zealand than tidal energy and for this reason four wave and two tidal schemes have been selected to populate the GEM input data file.

Six wave farms with three different devices (Pelamis 750 kW, Pelamis 1.5 MW and Single Point Absorber 750 kW) were assessed. The yield capacity factor of the Pelamis 1.5 MW and Single Point Absorber 750 kW, seem high as they originated from modelled devices having high levels of power in a wide range of conditions. The average capacity factors of the 3 devices at each location have been used to populate the GEM input file. This yields capacity factors between 0.55 and 0.65 which might be achieved in 15 years if full commercial development of the devices is realised. The four wave sites with the highest capacity factor have been selected to be used as input for GEM. These are Port Waikato, Taranaki, Westport and Southland.

Mapping performed on tidal current velocities suggests that the best locations to capture tidal energy in New Zealand are Cape Reinga, Cook Strait and Foveaux Strait. Cape Reinga was not further studied because of the lack of transmission and distribution infrastructure. The detailed study on Foveaux Strait indicates that the turbine array provides only a small amount of energy in comparison with the energy that could be potentially harnessed from the Cook Strait currents. The likely cause of this difference is the smaller accessible area and lower current velocities. The report pointed out that large harbours and estuaries could offer a potential tidal resource. Crest Energy is currently looking at deploying a test turbine in the Kaipara harbour in Northland and therefore it seems reasonable to use the Kaipara harbour as the second potential tidal resource instead of the Foveaux Strait, the first one being the Cook Strait.

In a similar way to the wave energy, various devices have been modelled and the average capacity factor of the best sites (i.e. CS2, 3 and 4) has been used to populate GEM. As no specific information about Kaipara harbour was available the Commission has assumed a similar array size and capacity factor as for the Cook Strait sites.

The Commission has spread the six schemes evenly from 2025 to 2035 with the highest capacity factors sites developed first.

The table below provides the data which will be used as marine input data in GEM.

Table 1:    Wave and tidal schemes