Tidal Power in New Zealand
Tidal power has a lot of things going for it - it is renewable and reliable as a clock but it hasn’t been exploited much in NZ due to uncertainties about the future structure of the power industry here.
In 2011, resource consents were successfully obtained for a tidal power station in Kaipara harbour. This would consist of 200 underwater turbines with enough generation to power 250,000 homes but it got put on hold because of the chaotic effects of privatisation on the power industry and the possibility of a future Labour/Green government centralising (meaning organising) power once more.
There are several forms of tidal power. In Kaipara, the turbines were planned to be 30 metres deep in a channel where the tidal flows are particularly strong. This type of system ( termed Tidal Stream Generation) does not interfere with the action of water and sediment appreciably but there may be some issues with marine life getting caught in the blades of the turbines or avoiding the area due to Electro Magnetic Forces EMF, or underwater noise. The proposal did however pass an assessment by the Environment Court
There are other forms of tidal power that can supply storage that integrates with solar or wind energy with less of an environmental impact. One such is the artificial Tidal Lagoon. This is circular walled structure with a turbine built in a place where it does not interfere with the local ecosystem. Extra seawater can be pumped into the enclosure during times of peak solar or wind production, and the water released on demand as long as the tide is at a generally lower level than the water inside.
At least two other locations in the Cook Straight and also the Chatham Islands already have consents and are just waiting for the right political environment.