Liverpool: huge tidal power plant on the Mersey could make city a renewable energy hotspot

Posted: August 3, 2019 by oldbrew in Energy, Tides
Tags: , ,

Map of the Manchester Ship Canal (= blue line)
[click on map to enlarge]

H/T TechXplore

Sounds expensive. But as Liverpool is near the start of the Manchester Ship Canal any barrage should have low impact on shipping, in theory at least. As far as a ‘climate emergency’ is concerned, I’ve lived near the Mersey for a long time and haven’t noticed anything out of the ordinary with the weather – so far at least 😐

Liverpool has declared a climate emergency, says The Conversation.

The mayors of both the city itself and the surrounding “city region” have recognised the emergency, and both have suggested that a tidal barrage on the River Mersey could form part of the solution.

And on a recent visit to the city, Labour leader Jeremy Corbyn said his party would support the £3.5 billion project.

Two years ago, I teamed up with colleagues at the National Oceanography Centre and University of Liverpool to look at how to realise the River Mersey’s energy potential: we concluded that a tidal power station could be part of the solution.

So what actually is a “tidal barrage”, and why do we think the Mersey is so suitable?

A tidal barrage generates electricity in a similar way to traditional hydroelectric power, using a dam (or barrage) to create a difference in height between two bodies of water.

As tidal waters flow in and out of the estuary, the barrage blocks the flow, raising the water level on one side. When the desired difference in water level is reached, the water is then allowed to flow through turbines, generating electricity.

Tidal barrages can operate in both directions and, as the tide goes in and out twice a day, are capable of producing electricity four times a day.

A few different factors make the Mersey an ideal place for a barrage. Its tidal range (the difference in water level between high and low tide) can be 10 metres or more at spring tides—the UK’s second highest, while a narrow channel at its entrance (known as “The Narrows”) means the barrage could be shorter and thus cheaper to construct. It’s also close to a large urban area, with lots of electricity demand.

We estimated a Mersey barrage could produce 0.9 to 1.5 terawatt hours of electricity each year. A terawatt is a million million watts, so this is a lot of energy—enough to supply electricity to about 300,000 homes, or more than all the homes in the city of Liverpool.

The technology has been around for a while. The world’s first tidal barrage was completed in 1966 on La Rance river in Brittany, France, and is still operational today. However, the high initial costs and potential environmental impacts mean there are still very few of these projects worldwide.

The idea to generate energy from the River Mersey’s tides was first put forward in 1981, with a series of proposals and feasibility studies since. As ever, the key issues are financial and environmental.

Full article here.

  1. oldbrew says:

    As the giant Fiddlers Ferry power station is closing in March 2020 something needs to replace it.

    The river is the Mersey.

  2. A C Osborn says:

    Yes let’s add even more intermittency to the Grid at massive cost.

  3. Graeme No.3 says:

    From your text I translate terawatts as 0.9-1.5 million MWh per year, leaving houses getting a maximum of 5MWh per year. Also, at £3.5 billion (which I take to be 3,500 million) construction cost spread over 20 years means a cost of £117 – £194 a MWh.
    Seems a decimal point dropped somewhere.
    The Rance river barrage only works one way now (or did in 2016) and was troubled by weeds. Anecdotal evidence only, but the source was an engineer with green leanings who was a bit doubtful of its value. There was also some silting of the estuary downstream.

  4. BoyfromTottenham says:

    Aw, gee, it generates power four times a day! How useful. Does it coincide with breakfast, lunch, dinner and beddy-byes? Oh no, the peaks are 30 minutes later each day… Never mind, businesses can work around this little inconvenience, can’t they? Are there any huge elevated dams nearby to use as pumped storage? I thought not. What a load of codswallop.

  5. JB says:

    “Those who are anxious to precipitate a measure will always tell us that the present is the critical moment; now is the time, the crisis is arrived, and the present minute must be seized. Tyrants have always made use of this plea; but nothing in our circumstances can justify it.” American Anti-Federalist paper #38

    “…the primary function of government is not to maintain freedom and security, but to ‘help business.’”p44 Our Enemy, the State

    “The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be lead to safety) by menacing it with an endless series of hobgoblins, all of them imaginary.” H L Mencken

  6. ivan says:

    I notice that this stupid proposal has reared its head again only after Jeremy Corbyn said his cronies said they would support it. Strange that, if it is so good there should be no need for public money, because private investors would be scrambling to hand them money.

    The Swansea tidal project was stopped because there was no government money forthcoming. If it can’t be built or run without taxpayers money being poured in to support it then any project like this should never be started and,like all unreliable renewable energy projects there should be NO subsidies or favouritism for their product – let it live or die on the open market.

  7. stpaulchuck says:

    whose brother-in-law is going to get the contract?? Another massively expensive boondoggle to line someone’s pockets with tax money.

  8. Gamecock says:

    That’s what I was thinking, BfT. People use electricity all hours of the day; four times a day is a declaration of failure before even starting.

  9. ivan says:

    Don’t forget it takes 2.75 hours plus for the tide to turn so in fact it would be generating electricity for about 12 hours out of every 24. Every 3 hours it generates electricity with the first of those 30 3 hours producing just enough to make the recording meters twitch, it could even taper off for the last hour as well depending on design. They end up with 4 hours useful electricity every 24 hours – this is why such schemes are useless.

  10. ivan says:

    it should have been ‘Every 3 hours it generates electricity with the first of those 3 hours producing’

    Sorry, fat fingers late at night.

  11. oldbrew says:

    It’s also close to a large urban area, with lots of electricity demand.

    Yes, and there are a lot of buildings close to the river banks on both sides 🤔

  12. pochas94 says:

    Make-work projects have been a feature of advanced civilizations as far back as the Pharaohs. They generate economic activity and keep the people busy and out of trouble. And, as long as they serve absolutely no useful purpose, they create an attractive image that adds immensely to their environment. Otherwise they can become an eyesore and a nuisance.

  13. P duncan says:

    Your article doesn’t state the power output. These barrages have added value as a road and rail bridge and also flood barriers. You need to add up the cost of all three to cost it.

  14. oldbrew says:

    The Mersey has few flood issues these days, certainly none worth spending billions on. And there are already two road bridges across the river from Widnes to Runcorn, one opened in 2017 with 3 lanes each way (pic below).

    There’s also a rail tunnel under the Mersey at Liverpool.

    And the Queensway and Kingsway road tunnels.

  15. pochas94 says:

    @oldbrew: That bridge is a public works project that serves a useful purpose, that is not an eyesore. It does happen.

  16. oldbrew says:

    Another new road bridge over the Mersey will be built in Warrington, only a few miles east of the one in the pic above. [April 2019 report]
    – – –
    Not forgetting the massive Thelwall viaduct taking the M6 motorway over the Manchester Ship Canal and the Mersey east of Warrington – 4 lanes each way…