Is deep sea mining a threat to offshore wind?

Six developers have warned that the New Zealand government could set offshore wind in the nation back by 50 years if it backs plans for seabed mining in South Taranaki Bight. As governments worldwide look to balance the needs of different industries in their waters, the growth of seabed mining is a cause for concern.


May 21, 2024

  • New Zealand is considering plans for seabed mining in its waters
  • Six developers warned this could set offshore wind back 50 years
  • Seabed mining could become a global issue for offshore developers


Social media has been abuzz this month as Australia has awarded support for 12 offshore wind farms totalling 25GW. There’s still a long way to go until turbines are spinning in its waters, but the industry has taken huge strides.

However, an argument is brewing in neighbouring New Zealand that highlights an emerging threat to the offshore wind industry.

New Zealand reportedly has the potential for more than 2,500GW of offshore wind farms, mainly floating, and the government has confirmed it is looking to introduce legislation to fast track development of offshore wind farms.

But the government is also facing criticism from wind developers about its plans to fast-track the development of another industry: deep-sea mining. Mining group Trans-Tasman Resources is seeking government backing to extract iron, titanium and vanadium from the seabed of South Taranaki Bight, off Patea, for up to 35 years.

Developers BlueFloat Energy, Elemental Group, Parkwind, Sumitomo and Taranaki Offshore Partnership, which is a joint venture between Copenhagen Infrastructure Partners and New Zealand Super Fund, have jointly written to the government to warn it about the damage that allowing deep-sea mining could do to the country’s nascent offshore wind sector. Specifically, they have warned that it could set back development of New Zealand’s offshore wind industry by 50 years, until the 2070s.

This is an argument we may see in other countries in the coming years.


Seabed disruption

The developers have claimed that fast-tracking TTR’s plans for seabed mining would damage the seabed, making it incompatible for offshore wind schemes both during mining and for many years after. They said this could also put off investors that are looking to invest in the offshore wind sector in New Zealand.

They have written that the sub-sea mining projects would “significantly disrupt the seabed floor, up to a depth of 11 metres” and make it impossible to install wind turbines and cables. They wrote: “Even after an extended period of resetting, significantly more expensive foundations and equipment will be required in order to build offshore wind in the future, resulting in higher electricity prices.”

By delaying the construction of early offshore wind projects in South Taranaki Bight, New Zealand risks derailing plans to establish the country’s offshore wind sector.

Alan Eggers, chairman at TTR, accepted that seabed mining operations and offshore wind farms could not be built on the same sites at the same time, but said they could be compatible in similar areas: “In the medium-term, once we’ve been through and harvested the mineral on the seafloor, it’s possible they could establish wind farms,” he said. TTR also criticised the offshore wind industry’s “hostility” to seabed mining and its goal to stop TTR “from pursuing its lawful development of natural resources”.

We expect to see similar disputes in other countries. Demand for critical materials such as lithium and cobalt is growing as countries seek to step up their energy transitions, while also trying to diversify away from reliance on China. Nations considering their plans for seabed mining include Brazil, Canada, Germany, India, Russia, Singapore, the UK and the US.

The United Nations International Seabed Authority (ISA) said some countries are applying for permits to explore the potential for deep-sea mining in international waters, and the ISA is working on regulations about how and when they could do it.

New Zealand is also not the only country where deep-sea mining has been controversial. Canadian firm Nautilus Minerals has been developing the Solwara 1 project off the coast of Papua New Guinea to extract copper and gold since the mid-2000s, and it secured rights to develop the project in 2006. Since then, Nautilus has faced delays to the scheme following ownership disputes and local opposition, but its proposal resurfaced last year. If it permits deep-sea mining, New Zealand may see similar opposition as in Papua New Guinea.

As well as making it harder for offshore wind developers to find sites for projects, the wider concerns about deep-sea mining relate to the potential impact on fragile and diverse marine environments by harvesting seabed minerals. These risks include the direct harm to marine life; long-term disruption to species and ecosystems; potential impacts on fishing and food security; and the knock-on effects on the climate and nearby communities.

In addition, the damage wrought by seabed mining could be entirely unnecessary if the same minerals could be found on land, or if technological innovations mean those raw materials are no longer needed.

Opponents of offshore wind may raise an eyebrow. Fishing and shipping companies have long expressed their concerns about offshore wind and its potential impacts on the seabed, and now offshore wind firms are taking a similar position with a different emerging industry. One crucial difference is that the disruption of building an offshore wind farm is far shorter than mining the seabed for decades, and we have seen the offshore wind developers taking steps to limit damage and promote biodiversity.

Governments in established offshore wind markets have faced pressures for many years to balance the competing needs of the different industries and users of their waters. Now there looks set to be another powerful industry for them to take into account.