Electricity Generation from Tidal Power In New Zealand

Why Tidal Power?
Making it work
The Origin of the Energy
Tidal Phases - the terms
The Political Will

Why Tidal Power?
There are many advantages with tidal power.  Firstly the energy is free.  Secondly many settlements in New Zealand started around harbors so there will be low transmission losses.  Thirdly it is reliable, tides can be predicted many years in advance and they will occur at a given time.  Herein lies the problem.  The time that the tidal flow occurs may not be ideal in as far as demand is concerned.  So tidal generation should be coupled with some form of storage.  Hydropower makes an ideal storage choice. Water or energy could be stored in these damns for times when power could not be generated at the tidal stations.

Making it work
Listed below are some of the possible elements that could be used to make tidal power work.

Area of Concern



Project Management, Engineering, Planning

AEC Professionals Inc
Lindsay Leveen


Tidal Power Expertise

Mulgor Consulting Ltd
Derek Goring


Generating Equipment

There are many sources of equipment

General Electric, Siemens and Hitachi also sell turbine generators.

Financially Interested Party

State Owned Enterprises


The Origin of the Energy
The origin of tidal energy is the rotation of the Earth.  As the Earth rotates on its axis the moon-facing tides sweep around the globe.  This causes friction, so earth's rotation is very gradually slowing.  The moon's orbit will also be affected.  The moon is pushed away from earth by 3.8cm/year in order to conserve the angular momentum lost by earth's reduced spin.  This will reduce the moon's orbital velocity, and in turn very slowly increase the length of a lunar month.

Tidal Phases
Terms are often used such as neap and spring tides.  The diagram below helps explain these.

The final price paid for electricity in New Zealand varies.  Here is a site that lists the price that retailers pay the generators for electricity:
Tidal power would have to compete with electricity generated from LPG imported into NZ from Australia or Indonesia at about $US5- per million BTUs If the plant has a heat rate of 7,000,000 BTUs per mega watt hour (best combined cycle) then the cost of the imported energy to generate power is $US35 per mega watt.  Capital and other operating costs for a combined cycle plants are about $US25 per mega watt so the cost of power is about $US60 per mega watt.  This is the value of electricity at the generation station.  To get it to customers one has to add the cost of transmission and distribution.  The above site lists the price that the retailers pay.  These prices were current in May 2004.

The Political Will
Who owns the hydro generation plant in New Zealand?  The government.  So for any chance of this idea getting off the ground it is the government who will need to provide the leadership.

Note: linked individuals and organizations don't necessarily share or agree with the views expressed on this page.

See more thoughts on Energy and the Earth

What is TVH?