Environmental impacts of marine energy devices

Tidal and wave energy are a potentially useful energy resource to the UK and around the world. They will reduce COemission compared to fossil fuels and reduce the environmental impact of our energy use. But will using these energy source affect the environment in other ways? How do we measure environmental impact on something that hasn’t even been built yet? We can answer these questions using numerical models of marine energy devices and look at how they change the physical characteristics of the seas in the area. We can then try and link that to ecological changes. We finally then have to decide if this is a “big” impact or a negligible impact. How do we do this? Again, modelling can help by simulating various scenarios, such as sea level rise or large storms.

Below are some images of simulations done in the Pentland Firth, Scotland on the impact of placing 400 tidal turbines in the channel. We use the latest multiscale modelling technology enabling us to simulate a large portion of the continental shelf, whilst still resolving individual turbines.

Multiscale mesh

Multiscale mesh of the Pentland Firth and surrounding shelf. Resolution varies from 20km to 18m (three orders of magnitude change)

Pentland Firth bathymetry

Bathymetry in the Pentland Firth region. The shallow area south of Stroma (the Inner Sound) is the prime area for tidal turbine placement.

Mean tidal velocity over 30 days

Mean tidal velocities calculated over 30 days show the asymmetry of the tides in this region. A perfectly symmetrical tidal flow would show zero mean velocity.

Mean bed shear stress difference for 0-400 turbines

Difference in mean bed shear stress for zero and 400 turbines placed in the Inner Sound. Red colours indicate a reduction in bed shear stress when turbines are in place and therefore indicate areas where sediment would build up. Blue indicates areas where bed shear stress increases and hence sediment may be removed. Sediment is one of the controls on bethic fauna in the region.