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.

via Tallbloke’s Talkshop

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August 3, 2019 at 01:41PM