Tidal Range – the undead of renewable energy?

Why is it that tidal range energy generation just won’t go away?

Efforts to promote a Severn Barrage faltered in 2011 and, despite recent efforts to retain their Development Consent Order, it seems that plans for a tidal lagoon by Tidal Lagoon Power in Swansea Bay may have come to an end for now.

But the number of tidal lagoon and barrage projects (otherwise known as tidal range) around the country continues to grow, attracting support from across the political spectrum.

Why are features and benefits of tidal range, that seem to be obvious to so many observers, missed by ‘the mandarins’ in Westminster?

Is our thinking too short-term?

Our Victorian forebears understood the benefits of bequeathing assets - reservoirs, water, bridges and embankments - that would serve their children, grand-children and generations to come.

In the same way, tidal range projects are designed to operate for at least 120 years and probably even longer. The benefits they offer are multi-functional and multi-generational and will continue to be delivered long after their capital cost has been repaid.

In comparison, modern nuclear plants are likely to be operational for up to 60 years. No long-term added benefits after that … just long-term and expensive decommissioning costs to be borne by future taxpayers.

Wind and solar energy farms have a design life of 30 to 40 years. The energy they produce, when they produce it, has become remarkably cheap. During the life of a tidal range scheme though, any wind or solar project will have to be decommissioned and rebuilt three or four times. How then do costs stack up?

Silo thinking?

Government Departments tend to worry about their own problems; BEIS worries about energy security and stability, DEFRA about the environment, DWP about employment. Each has their own way of assessing contributions and value for money.

Tidal range projects don’t fit neatly into any one of these silos – but contribute powerfully across all three.

A tidal lagoon is a significant low-carbon renewable energy power station, falling within BEIS’ remit. It will also provide high-GVA employment opportunities around the UK’s economic fringe – a benefit appreciated by DWP. The ability of a sea wall, whether barrage or lagoon, to help mitigate the impact of rising sea levels is of real value to coastal communities and DEFRA.

The breadth of benefits that tidal range offers is at once its greatest strength and, at the same time, to the ‘silo’ culture, its biggest weakness.

Evaluations of tidal range projects to date have almost exclusively focused on comparisons of the cost of energy produced against other sources such as wind, solar and nuclear. But this is comparing apples with pears. None of the other solutions to meeting our Net Zero targets offer anything like the co-benefits that come with a tidal lagoon or barrage. These benefits should be taken into account. But they aren’t.

Let’s favour the fair-weather favourite?

The less the UK capitalises in its natural resources and reduces its reliance on imported fuels (be that gas, LPG or uranium) the better.

The success of the wind and solar energy industries over the past 20 years is to be applauded. Their contribution to UK energy needs and achieving Net Zero targets is essential and should not be undervalued.

But there are problems looming for a network that increasingly relies on intermittent supplies of energy. When the wind doesn’t blow or the sun doesn’t shine, what fills the gap? Not just for minutes or hours, but potentially days and weeks?

That’s where tidal range steps in. Tidal range, too, is home grown and totally reliable.

Indeed, it is the tides’ utter predictability and reliability that makes it so attractive as an energy provider. No need to worry if the wind is going to blow or the sun shine … the tide will rise and fall twice a day, 365 days a year. Tidal range projects along the coast of the UK would provide reliable, steady power throughout the day and night, perhaps helping those responsible for Grid security and stability sleep better at night?

Time for a fresh assessment

Tidal range has too much potential and too many supporters to be ignored.

Recent assessments of its potential value to the UK have been narrowly focused. Rather than concentrating on simple cost of energy models, there needs to be recognition of tidal range’s unique multi-generational operating life, extensive co-benefits and contribution to the UK’s energy security and stability.

A fresh assessment of tidal range, recognising these factors and using up-to-date independent engineering and financial models is needed to provide a true comparison of its value for money against other renewable energy sources.

Only then can the potential of tidal range truly come to life.