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Swansea Barrage Represents a Key Opportunity


Charles Hendry’s report into the exciting Swansea Lagoon has given it the thumbs up.

The former energy minister concludes:

“I started this process with interest but sceptical. The more evidence I have seen, the more persuaded I have become that tidal lagoons do have an important role to play and there should be a government strategy in place to help this happen.”

But it is not a cheap source of power. It has enemies. Among them is Jonathan Ford, writing yesterday in the FT,

Strangely, he quotes John Constable of the so-called Renewable Energy Foundation (REF), who lambasts it. The REF is a bogus organisation that does the opposite of what its name suggests. A simple Google search will reveal this, such as this piece.

That aside, it is important to factor into any calculation about this investment that the lagoon will last 3-4 times longer than Hinkley or any other nuclear power station, and so its costs should be factored over around 100 years.

Hydroelectric power dams last for a at least this length of time. Admittedly the conditions for the barrage are slightly more stressful, being in salt water, but the area of Swansea Bay to be occupied by the barrage is a doubly sheltered one – both by the Bristol Channel and the horseshoe shape of the Bay itself.

Let’s recall nuclear power’s toxic legacy, and EDF’s abysmal record, and nuclear power stations’ own unreliability (often offline for weeks at a time for maintenance and safety), which should also should be factored in.

Balance this against the modular nature of the turbines in the barrage (if one fails the others will keep working) and the predictability of the electricity (from the predictability of the tides).

Ford argues that nuclear is continuous source of power and the barrage is not, but the barrage has the ability to store energy (as water) within itself. The imminent availability of cheap electricity storage technologies will also help match supply with demand.

Tidal barrage and lagoon schemes are a new technology. Backing them will position the UK well as a world expert, leading to further lucrative business for UK plc. China is already utilising it.

We have delayed long enough and let China get ahead. Let’s get on with it.

Content Discussion

Robert Hargraves's picture
Robert Hargraves on January 18, 2017

Read this clear analysis of the issues, from the Energy Matters blog:

Jarmo Mikkonen's picture
Jarmo Mikkonen on January 18, 2017

the mean output is around 60 MW and as we shall see maximum output of 320 MW will only be achieved momentarily each month. For a lot of the time output is zero. £1.3 billion seems a huge amount to pay for a 60 MW power station

It’s over 20 million pounds per megawatt. If an EPR had a similar cost per MW, it would cost over 33 billion pounds

Roger Arnold's picture
Roger Arnold on January 18, 2017

For the type of tidal barrage that is being planned for Swansea Bay, the analysis that Robert references above looks correct to me: big intermittency issues, no baseload capability. And, of course, hugely expensive and disruptive to the bay’s ecosystem.

It’s worth mentioning, however, that other designs are possible. In an article I wrote a few years back (The Great Mexicali Energy and Shipping Canal), I sketched out a rather different sort of tidal power generation to tap the twice-daily 5 to 7 meter tides at the northern end of the Sea of Cortez (or the Gulf of California as it’s known in the U.S.) It more resembled a regular hydroelectric power system, and would be capable of supporting 24/7 power at regulated levels.

The key to those capabilities is that what I proposed was not a simple tidal lagoon. Rather, it was a series of two types of artificial lakes constructed along the course of a very large canal. Half of the lakes were high tide recharge lakes, and half were low tide discharge lakes. The two types alternated along the course of the canal near the sea. Both were connected to the canal through one-way flow gates. Water flowed into the high tide recharge lakes whenever the water level in the canal was higher than the water level in a given lake. It flowed out of the low tide discharge lakes whenever the water level in the canal was lower. The high and low lakes were connected to each other through power turbines. So the charge of water captured at high tide was parceled out as needed over the period until the next high tide.

What made that design feasible — as I saw it, anyway — was that the canal and lakes would all be constructed in largely uninhabited low-lying desert of the Colorado River delta area. The soil there is lightly compacted alluvial material that should be easy to excavate and sculpt.

That approach, unfortunately, would not work particularly well for Swansea Bay. The bay would need to be divided into two roughly equal parts, separated by a low dam. The problem is that two parts would not have sufficient surface area to hold enough water for interesting amounts of baseload power generation at the low heads involved. They could, however, provide useful capacity for pumped hydroelectric storage.