Marine renewable energy in the UK

Middlegrunden Wind Farm
Middlegrunden Wind Farm
In recent years, the development of offshore renewable energy projects has been dramatic. It is expected that offshore renewable energy installations are likely to be the most intensive engineering interventions in UK coastal waters in the next decade. Of the current technologies in the UK, wind energy is the most developed, a number of wave and tidal power demonstrator projects are currently underway and applications for full scale wave and tidal projects are under consideration.

WDC recognises the very real threat posed by climate change to whales, dolphins and porpoises and the efforts required to mitigate this.

To try and reduce the effects of climate change and to meet requirements to reduce greenhouse gases governments are investing in new renewable energy technologies. Much of the development is going on out at sea and marine renewable energy, which is typically regarded as an abundant, inexhaustible and non-polluting resource, has the potential to contribute significantly towards the targets set by governments to produce energy from renewable sources.

Yet it is important that any offshore development should be undertaken with adequate consideration of the potential negative impacts on whales and dolphins and the wider marine environment. In trying to solve one environmental problem, we should not create another.

In recent years, the development of offshore renewable energy projects has been dramatic. It is expected that offshore renewable energy installations are likely to be the most intensive engineering interventions in UK coastal waters in the next decade. Of the current technologies in the UK, wind energy is the most developed, a number of wave and tidal power demonstrator projects are currently underway and applications for full scale wave and tidal projects are under consideration.

As a result of the European Commission’s proposed measures for renewable energy supplies and reduced carbon dioxide emissions, the UK Government has announced ambitious targets. Currently, only 2% of power comes from renewable sources. The UK Government aims to increase this contribution to 10% by 2010 (18% in Scotland) and 15% in 2020. This will include the installation of 1,000s of wind turbines around the UK coastline. It is estimated that 15-20% of the UK’s electricity demand could be met by wave and tidal energy. Renewable energy decision making powers have been devolved.

Consideration of where developments are allowed could influence the impact that they have. The scale and extent of environmental impacts resulting from such developments will vary according to location, design and the size of the development and should be appropriately monitored, with a view to an adaptive approach as we learn more about these novel technologies and the effectiveness of mitigation and management measures.

Noise from construction, in particular pile-driving which is used in the majority of foundation types particularly for offshore wind farms, may give rise to extremely loud noise levels that are high enough to impair the hearing system of marine mammals near the source, and disrupt their behaviour at considerable distance from the site.

In addition, noise arising from the operation of marine renewable energy may also have adverse effects on whales and dolphins in UK waters. Collisions with tidal arrays are possible if developments are consented in areas frequented by whales, dolphins, porpoises and seals.

Monitoring of noise levels arising from piling has taken place at a number of the UK Round 1 wind farms. These measurements have confirmed the potential for high noise levels, although these vary between sites depending upon substrate type, bathymetry and installation methods.

There is seldom enough detailed baseline data on marine mammal distribution prior to industrial activities, which means that any potential effects post construction cannot be identified (these knowledge gaps also need to be addressed by other industries, most notably in the hydrocarbon exploration and extraction sectors and the military). Studies during the construction of two offshore wind farms in Danish waters revealed a decrease in harbour porpoise abundance during the construction phase at both sites. More widely data show mixed results and so assessment must be made on a site by site basis.

Operational noise transmitted from turbines through structures into the sea may give rise to barrier effects or avoidance behaviours; although initial noise measurements suggest that the risk of this is low. Operational noise of smaller turbines (<1.5MW) is unlikely to affect whales and dolphins. A study of wind farms in Danish waters found no significant influence of the wind farms on the occurrence of harbour porpoises. Operational noise of proposed larger turbines (4-5MW) cannot yet be reliably assessed, though it is likely that these turbines will be noisier and influence a larger sea area. The Scottish Strategic Environmental Assessment for wave and tidal power considered that operational noise from tidal turbines may be a significant risk, giving rise to the potential for barrier and other disturbance effects. This may be a concern in narrows or other constrained areas utilised by migrating or foraging species.

Decommissioning of offshore renewable energy installations at the end of their commercial life may involve noise, creating activities such as cutting, drilling and the use of explosives to ensure compliance with government regulations requiring re-instatement of the seabed. The problems associated with the use of explosives are discussed in the section on ‘Oil and gas exploration’.

WDC advocates appropriate siting of developments and at least two years of baseline surveys before development.

WDC is consulted on a number of marine renewable development initiatives every year, our responses to these applications can be read on our renewable consultations page.