FAQs

Why don't we put all the wind turbines out to sea?

Wind turbines can be sited offshore, where the wind blows harder and the available resource is enormous. Because of the flat surface of the sea wind turbines work more effectively. The wind speeds can be up to 25% higher 10 kilometres from the shore than those at the cost. Large-scale projects with much larger turbines can be visually well removed. Furthermore the wind at sea is generally less turbulent than on land. Wind turbines located at sea may therefore be expected to have a longer lifetime than land based turbines. (1)

In Europe, there are 600 MW of offshore wind farms representing 2% of current installed wind capacity. The European Wind Energy Association (EWEA) industry target sets out an increase to 13% by 2010 and 39% by 2020 - a total of 70 GW within 16 years.(2) However there are no offshore wind farms, or planned ones in New Zealand at the moment.

In comparison with onshore sites offshore wind generation in New Zealand is not cost effective yet. There are significantly higher construction and maintenance costs related to offshore wind farms and it is also very expensive to connect the electricity to the onshore grid. Another difficulty may be obtaining an approval for offshore developments.(3) Up to now offshore wind turbine technology has only been tested in relatively shallow water (in 5 to 15 meters depth). Compared with Europe the waters around New Zealand are very precipitous which means that there are not many suitable sites at the moment.

As we have nearly equivalent wind resources onshore, offshore development in New Zealand isn’t on the cards at the moment. But it might become an interesting option for the future when deep-water technology advanced and offshore sites are more cost-effective.

Notes:
(1) www.windpower.org/en/tour/wres/offshore.htm
(2) www.ewea.org/documents/0927-Offshore.pdf
(3) www.ecan.govt.nz/Energy/ren-energy-report-02/section-2-1-1.html

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