Marine Energy

NZ Renewable Energy Overview

Approximately 75% of New Zealand’s electricity generation comes from renewable sources, particularly hydro, geothermal and wind (NZEQ, 2012).  For the last 5 years NZ governments have maintained an aspirational target of achieving 90% renewable electricity generation by 2025 and past governments have introduced legislation to promote the uptake of renewable energy.  Seeking to develop another renewable resource, marine energy, broadens the NZ energy portfolio and improves energy security, both key issues for an isolated nation like NZ.

To date New Zealand has invested very little in developing our marine energy resources or technologies but our natural resource advantage could make marine energy a significant potential contributor to future energy supply. Possibly as much as 20% of New Zealand’s electricity could be generated from marine energy sources (Huckerby & McComb, 2009).

Most NW European countries, particularly the United Kingdom, Ireland, Denmark, France, Spain and Portugal, are currently investing significantly in marine energy with the UK being the current leader in technology developments. Canada, the United States and Australia all have active projects to develop marine energy technologies and particular sites and interest in the Asia-Pacific region is growing rapidly.

In New Zealand uptake of marine energy is likely to be gradual and progressive. The development of wind energy in New Zealand provides a good template for the development of marine energy. The first wind turbine, at Brooklyn in Wellington, was an R & D demonstration project installed in 1993. Having established the potential at that site, the first wind 7-turbine wind farm was built in 1996 with the second following in 1999.  It wasn’t until about 2004 – more than 10 years after the first turbine was installed before developments began to accelerate and locally developed turbines were constructed. A similar path is likely for marine energy technologies – early demonstration projects, followed by larger and widespread commercial developments, including the development of domestic technologies. Indeed the opportunity for the latter may be greater in marine energy technologies because the technologies are not as mature as the Brooklyn turbine was when it was constructed.

Renewable Energy Sources

Left: Manapouri Power Station (Wikipedia), Centre: Brooklyn Turbine (Wikipedia), Right: Solar power plant at South Auckland Forging Engineering’s Drury base (Meridian)
 
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Marine Energy Resources

Marine energy resources have significant potential when compared with other renewable energy resources as they have higher energy densities, compared with wind, solar, and geothermal resources.

Offshore ocean waves and swells generate substantial onshore energy fluxes. The main islands are exposed to the open Southern Oceans and capture the full effects of the predominant southwesterly ‘Roaring Forties’ winds.  These bring energetic swells and waves to our west- and south-facing coasts.  New Zealand’s wave resources are ‘world-class’.   Because of the long fetch area from the Southern Ocean these swell resources are less seasonal than some locations globally.

Meanwhile New Zealand has unusual tides, which sweep anticlockwise around our coast roughly twice a day, although they have only a small range (2 – 3 m). Consequently, tidal currents have lower velocities than in other countries.  Sites of higher speed currents are patchily distributed around New Zealand, where offshore islands, passages and seabed irregularities provide a focusing mechanism and there are large areas of significant tidal current flow, for example, Cook Strait.  A notable aspect of these regions is the depth of the water column.

resources

Left: Wave resource chart for New Zealand (PPL & MetOcean Solutions 2008), Right: Tidal resource chart for New Zealand (PPL & MetOcean Solutions 2008)
 

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Environmental Issues

Evidence from deployments of marine energy converters around the world to date indicates that environmental effects and competition for space will be limited.  Most marine energy technologies will be submarine and thus have no visual impact and very little impact on surface activities.  Indeed areas set aside for marine energy farms are likely to act as de facto marine reserves, assuming other uses are excluded from these areas.  Since most other marine uses seek to avoid areas of high swells and/or currents, marine energy projects are likely to be complementary to other activities.  Further, marine energy technologies are designed to eliminate or minimize any environmental effects. Marine energy technologies will also contribute to reductions in climate changing greenhouse gas emissions. In operation they generate little or nothing in the way of gas emissions.

Whilst marine energy technologies are still relatively immature and limited in their deployments, more data will need to be gathered to confirm the limited environmental impacts on marine ecosystems and marine fauna. However, it is already clear that marine energy devices will have a light ‘footprint’ on the areas in which they are deployed.  With a high value placed on the environment by NZ society, and the many unknowns relating to this new form of energy extraction, caution is natural and wise.  Nonetheless, there is no substitute for getting devices in the water to test them and their effects on the resources and the environment.

environmental

 

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Research

Whilst the marine energy resource potential off New Zealand’s coasts is generally understood, it has not been the subject of extensive R&D, such as has been undertaken in NW Europe and North America.  Many countries have undertaken national resource assessments out to the edge of their Exclusive Economic Zones and some have Strategic Environmental Assessments to identify areas with high potential for marine energy projects.

New Zealand has the 6th largest Exclusive Economic Zone in the world and the 10th longest coastline, so there is still much research to be undertaken.  The oceans are complex and investigating them is costly and difficult.

Key issues will be how to address environmental impacts as they are identified.  For instance, putting any marine energy converter in the sea may change the resource it is seeking to harness, e.g., a tidal current in a tidal channel.  Anticipating and quantifying these changes is important and addressing them will be a critical element to developing arrays of marine energy converters.

It is important to remember that promoting marine energy is not simply about generating clean power.  Other countries have much more serious future energy concerns than New Zealand, so they are investing heavily in offshore wind and marine energy.  A growing international market place is developing and it will focus on countries with attractive resources, which can produce power more cheaply than other places.  With this growing international market will come increasing requirements for new technologies and skills.

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Technologies

There are at least seven different ways to generate power from marine resources.  The most active developments are presently focused on waves, tidal currents and ocean thermal energy.  There are over 200 wave and tidal current devices actively being developed around the world.  These technologies are under development in a number of countries but almost all technologies are yet to mature.   The first full-scale tidal power device has been operating in Northern Ireland for about 3 years and the site may well extend to a small array.

In New Zealand a number of wave and tidal power devices have been proposed but only one, Wave Energy Technology – New Zealand, has been developed.

Technologies

Left: WET-NZ’s half-scale wave energy converter deployed at Akaroa Heads (WET-NZ), Centre: Illustration of an Openhydro tidal turbine (Openhydro). A technology similar to this was proposed for installation in the Kaipara Harbour by Crest Energy Limited. Right: MCT’s Seagen tidal turbine in Strangford Lough, Ireland (Charlotte Sterck, PPL)
 
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Supply Industry

New Zealand has capable and qualified industries with the creativity and flexibility to grasp the marine energy challenge. The response to the America’s Cup challenge in 1995 and 2000 is a good example of what can be achieved.  Oceans dominate New Zealand – 94% of New Zealand’s sovereign territory is ocean.  New Zealand’s prosperity in the 21st Century is likely to be increasingly derived from our oceans.

supply industry

Left: An RDCP being deployed in Karori Rip to collect current data (Craig Stevens, NIWA). Centre: Seaworks installing the TelstraClear cable in Lyall Bay, Wellington (Bob Waugh, BTW). Right: WET-NZ’s MEDF device being craned into the water at Seaview Marina (WET-NZ)
 
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NZ Projects

In the last 10 years up to 20 wave and tidal power projects have been proposed, though many have now fallen by the wayside.  Five projects have benefitted from an NZ Government grant scheme, called the Marine Energy Deployment Fund.  This fund was available for 4 years (2008 – 2011).  However, only three of the original projects are still in operation and two privately-funded projects have become dormant or have been abandoned.

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Summary

Development of marine energy in New Zealand faces some unique challenges: the harshness of the marine environment, the regulatory environment, willingness to invest and the present excess of electricity generation capacity. Current draft Government strategy and policy documents recognize the potential for marine energy but, since marine energy cannot make an immediate contribution, Government interest and funding tends to go elsewhere.  We need to see some long-term strategies and policies implemented to deliver the investments in marine energy projects, which at root recognize that world-class wave and tidal current resources are located around our coast and will have to be harnessed here, just as the oil and gas reserves in the Taranaki Basin have been.  The choice for New Zealand is to actively invest in R&D and technology developments now, so that we develop an export industry to service other countries with less advanced economies.

A dedicated long-term marine energy strategy, combined with a supportive R & D investment regime, would do much to promote uptake.  AWATEA is also championing a marine energy centre – for testing and demonstration projects in part to develop a domestic capabilities in marine energy.   A space allocation regime, similar to the oil and gas permitting regime, should be implemented to avoid the ‘land grab’ and subsequent moratorium, which have adversely affected aquaculture investment.  Such a land grab is likely to occur with tidal power sites, since they are relatively regionally and areally restricted.