UK marine energy - tidal lagoon power advances

The Cardiff tidal lagoon project has secured a grid connection on its way to becoming the first full scale power facility of its type.

While the United Kingdom is leading the way with offshore wind, it is also making pioneering strides with marine power technologies.

Tidal lagoon power

One such area is lagoon power, which is being championed by the company Tidal Lagoon Power. Six projects are at various stages of development in the UK and while none are yet operational, the company is also investigating opportunities further afield in countries including Canada, France, India and Mexico.

Tidal lagoon power is based on the concept of harnessing the power in the ebb and flow of tides with the creation of an artificial lagoon – and the greater the range, the more power is potentially available.

Tidal Lagoon Power’s first project is in Swansea Bay on Wales’ south coast. Planning consent was granted in 2015 and final signoff by the government is being awaited, with the aim to start the four-year construction in 2018. The first power is expected to be generated in year three.

With a capacity of 320MW that is a ‘pathfinder’ project and the next coming up is a full scale project, ten times larger at 3,240MW.

Cardiff tidal lagoon

To be located between Cardiff and Newport in the Severn estuary, which has the second highest tidal range in the world, the Cardiff project has taken a significant step forward with the securing of a grid connection from National Grid.

And according to the project developers, it is expected to generate among the cheapest electricity of all new power stations built in the UK.

“Our offer to the UK government is to contract Swansea Bay Tidal Lagoon for a lower subsidy per megawatt hour than Hinkley Point C,” says Tidal Lagoon Power’s chief executive, Mark Shorrock.

“Looking at the pounds per megawatt hour unit cost of new build power stations, nuclear is currently priced in the nineties, the latest offshore wind projects are expected to drop into the seventies and our models show Cardiff Tidal Lagoon beating them all in the sixties.”

Continuing the comparison, the company quotes a review by former energy minister Charles Hendry that contracting Cardiff Tidal Lagoon’s 5,500GWh annual output adds less than £0.5 on average to annual household electricity bills, versus £2.39 for a similar portion of Hinkley Point C’s contracted annual output.

Current plans for Cardiff Tidal Lagoon comprise a 20.5km breakwater wall housing up to 108 tidal lagoon turbines within at least two powerhouse units.  By enclosing approximately 70km2 of the Severn Estuary, the project would pass an average of some 600 million m3 of water through its turbines on each tidal cycle – more than 11 times the volume of water available to the Swansea Bay project.

In addition to power generation, the facility could offer flexibility to the grid by holding back periods of power generation or pumping for storage. Up to 2,171MW of demand is permitted under the agreement with National Grid.

An interesting spinoff is expected to result for the environment. According to the Severn Vision Partnership Project, up to 7% of the intertidal area in the estuary could be lost to sea level rise by 2055, resulting in the loss of up to 40% of total saltmarsh habitat.  While affecting some intertidal and subtidal habitats, the Cardiff Tidal Lagoon would offer protection to a large stretch of the habitat under threat while providing additional feeding opportunities to overwintering and resident birds. 

Preliminary environmental and engineering studies have been under way for the past three years and a full application for development consent is anticipated in 2019.

Marine power innovation

More innovation in marine energy in UK is the Enabling Future Arrays in Tidal (EnFAIT) project, which is being led by Scotland-based tidal energy specialist Nova Innovation.

The aim is to extend the existing Bluemull Sound tidal array, claimed to be the first in the world to become operational, to six turbines to demonstrate that high array reliability and availability can be achieved using best practice maintenance regimes. The technology is an undersea turbine, much like a wind turbine.

Nova also is currently in the early stages of developing two tidal energy projects off the northwest coast of Wales.

A recent audit found that the northeast of England and Scotland is a leader in the offshore and subsea renewable technology, but a hotspot also is emerging at the opposite end of the country.

Marine -i, a collaboration of academic and other organisations, has secured up to £6.8m of European Regional Development Funding (ERDF) as part of a £9.3m programme to develop marine energy and other marine technology research, development and innovation activities in Cornwall and the Isles of Scilly.

Marine research has been identified as an area of high growth potential in this region in which the sea forms an important part of its history and livelihood and which has taken a number of innovative steps towards meeting its future energy needs.