Mapping what lies beneath
SCIENTISTS SURVEY SHIFTING SEABED TO FIND SAFE GROUND FOR WIND FARMS
DEEP beneath the Irish and Celtic Seas, off the North Wales coastline, lies a hidden landscape of glacial scars left behind by the last Ice Age 25,000 years ago.
In the darkness there are also vast sand dunes, some several metres high, which shift slowly across the seabed with the tides and waves.
For engineers looking to anchor the next generation of wind turbines, it is a landscape fraught with hidden dangers.
Hoping to provide solutions are geo-scientists at Bangor University, using sophisticated 3D techniques to map the seabed all round the Welsh coast.
“Sand waves can be a real nuisance,” said marine geologist Dr Katrien Van Landeghem. “That’s where geo-scientists come in – we map these areas to show how the sand moves.”
She is an expert in seabed morphodynamics – the study of how shifting ocean floors affect multi-billion pound engineering projects like windfarms.
Katrien expects coastal seas to play a key role in the Government’s green ambitions to power every home in the country with wind energy by 2030.
For this to happen, many more wind farms, in much deeper waters, will be needed.
In turn wind developers will need detailed maps of the seabed to ensure turbines are firmly anchored – and to avoid disturbing habitats.
Katrien, from Belgium but living in Colwyn Bay, said: “Offshore wind is going to be vital in the accelerated schedule to provide low-cost clean power because it is tried and tested – we know the technology works.
“But we need to ensure these developments are cost-effective yet sustainable for the seabed and the animals it supports. We are going to have to develop our seabed even more carefully now.”
Bangor University’s School of Ocean Science is working with German renewable energy giant RWE on the siting of the Awel y Mor wind farm extension off the North Wales coast. When built it will be one of the world’s biggest wind farms, more than doubling the size of its neighbour, Gwynt y Mor – already the world’s fifth largest.
Awel y Mor (Sea Breeze) will lie to the west of Gwynt y Mor (Sea Wind), which has 160 turbines spread across 80 sq km of Liverpool Bay. These stand 150 metres above the sea and generate 576mW of electricity. Awel y Mor will add a further 200 turbines. Beneath the waves they extend down 30 metres, their thick steel cylinders buried tens of metres deep to secure them to the seabed.
Next generation turbines could be further out to sea and anchored by chains to the seabed 100 metres down.
RWE’s Awel y Mor project manager Tamsyn Rowe said the Bangor University work is crucial: “We want to ensure our projects are developed as responsibly as possible.”
Much of the data and resultant imagery used by RWE has been gathered from the university’s survey ship Prince Madog.
It uses a multi-beam system emitting sonar signals that bounce back to provide incredibly detailed images of the seabed. Video and photographs are also used.
The School of Ocean Sciences began surveying the seabed in 2012 and have mapped hundreds of square miles.
“We have to make sure the integrity of the seabed isn’t harmed,” said Katrien. “That includes paying attention to where we lay the cables carrying the electricity generated back to shore.”