Environmental impact studies which are conducted early on in the development of wave and tidal-power schemes allow the schemes’ technology to be adapted to consider their impacts on marine ecosystems, according to a recent study which reports on a Swedish research wave park.
Harnessing the renewable energy of ocean waves along coastlines has huge potential and generating energy from renewable sources is one of the fastest growing industries in the world. This study reports on the Lysekil(1) research wave power park off the Swedish coast, which has been under development since 2005. Environmental and technology studies are being carried out at the same time, which enables environmental concerns to influence technological development.
The motion of the waves generates electricity using “point absorbing linear wave generators”, a type of wave energy converter (WEC). Buoys on the surface, via wires, drive generators anchored on the seabed; cables on the seabed then carry the electricity to land.
Some marine organisms colonise these buoys and buoy lines, including blue mussels, barnacles and algae, which increases biodiversity and species richness. For example, during the 2005 and 2006 summers, about 150 kg of organisms were estimated to have been attached to a single 3 metre diameter buoy. This may initially appear a cause for concern, in terms of the equipments’ efficiency. However, modelling suggests this biofouling does not impair the action of the buoy, and it is acceptable to allow it to grow on the wave energy converters.
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Concrete foundations anchoring the generators on the seabed are attractive to marine organisms and can act as artificial reefs. Complex foundations can be designed to provide more ecological niches, resulting in higher species abundance and diversity. However, new species might also be introduced which could affect existing species through competition, predation and parasitism.
The size of wave installations offshore will affect commercial fishing. For example, 1000 linear wave converters occupy an area of about 1 square kilometre. However, by acting as no-take zones and by providing artificial reefs, wave energy parks could become nature protection areas offering increased fish density, diversity and abundance.
Migratory birds are unlikely to be affected by most WECs, except perhaps for shoreline systems close to breeding colonies. However, a bigger impact is likely to be on marine populations that migrate or cover large areas while foraging, such as marine mammals.
Little is known about the long-term effects of underwater noise from construction and operation of WECs on marine species, such as whales, seals, dolphins and some species of fish that use underwater sounds to navigate, communicate, find prey and avoid predators. Additionally, further investigation is needed on the effect of electromagnetic fields, produced around sea cables, on marine organisms that use the earth’s magnetic field for navigation, such as migratory fish.
Although the technology is still under development, some forms are close to commercialisation. As all renewable energy installations have an environmental impact, the opportunity exists now for ecologists and engineers to work together to design wave power parks that address environmental concerns and conservation issues.
