The north-west’s first industrial revolution was built on coal, which was abundant in Lancashire. Its second could be built on wind and water, two commodities that remain plentiful.

With four large estuaries in the region, engineers at the University of Liverpool say that building barrages across them could provide more than 5 per cent of the UK’s electricity and a solution to the problem of how to increase the country’s renewable energy production.

Much focus has been on the Severn estuary near Bristol in south-west England. Its tidal range is the second highest in the world and it alone could provide 6 per cent of the UK’s energy, though there are fears for its wetlands.

But the north-west could equal it with four smaller schemes: the Solway Firth on the border with Scotland, Morecambe Bay, and the rivers Mersey and Dee.

Most work has been done on the Mersey. Peel Holdings, the property and energy company that owns the ports at the river’s mouth and much land along it, has produced a feasibility study for a scheme.

It is set to apply for planning permission within months but the battle could be hard, as environmentalists fear that a barrage could alter the estuary’s ecosystem.

Tidal barrages do not employ new technology. France built one at Le Havre in the 1960s. It was a test to see whether the idea worked. However, the country opted for nuclear generation instead. Engineers say that, while there was a big fall in wetlands and bird populations in the estuary at first, the ecosystem has now adjusted.

The Liverpool University research, in collaboration with Proudman Oceanographic Laboratory, suggests that the four barrages could meet about half of the north-west’s electricity needs.

Funded by the Northwest Regional Development Agency, the team investigated different types of tidal power, including barrages – which run from one bank of an estuary to another and guide water flow through sluices and turbines – using advanced computer modelling.

They found that the most effective mode of producing electricity was “ebb generation”, which involves collecting water as the tide comes in and releasing the water back through turbines once the tide has gone out.

However, “two-way generation”, which produces a less intense burst of power but is less damaging to the environment, could be a viable alternative.

Prof Richard Burrows, from Liverpool University’s Department of Engineering, says: “The best places to harness tidal power at meaningful scales are areas with a high tidal range such as estuaries. Tidal barrages would alter the natural motion of an estuary’s flow as the sea level changes, usually by holding back the water at high tide and then releasing it when the tide has subsided.

“This water level difference across the barrage is sufficient to power turbines for up to 11 hours a day, and, in terms of the four north-west barrages, the energy extracted could supply 5 per cent of UK electricity generation needs.”

He says that, apart from the environment, cost is the big stumbling block – they would be public infrastructure projects on the scale of motorways or big bridges, he points out.

Judith Wolf, from the Proudman Oceanographic Laboratory, says: “The problem with renewable energy generation is that it is intermittent; electricity can only be generated in line with the tidal flow. However, the tide arrives in the north-west around four hours after the Severn, so together they could increase the number of daily generation hours.

“Other tidal energy schemes around the UK coast could extend the generation window.”

The NWDA has also supported a study into a barrage across the Duddon estuary in Cumbria. Previous studies have suggested it could generate 100MW of energy – enough to power about 200,000 homes – and provide a new transport link that would cut 17 miles off the journey between Barrow and Millom.

Bendalls Engineering, part of the Carrs group in Carlisle, is a world leader in wave-power technology. It manufactured parts for “Sea Flow” and “Seagen” – the world’s first large scale grid-connected tidal turbines.

Marine current turbines are newer technology. They are driven by the water currents beneath the surface, which give a consistent energy supply.

Bendalls assisted with detailed design and completed all fabrication, assembly and in-house testing of the “Sea Flow” machine. It has been operating off north Devon near Lynmouth since 2003.

More recently, Bendalls has been involved in the manufacture of the top support structure and hydraulic lift mechanism for “Seagen”, a 1.5MW tidal turbine at Strangford Lough south-east of Belfast. “Seagen” is the world’s first large-scale grid-connected tidal turbine of its type and is working well.

Norman Bettison, managing director of Bendalls, is a veteran of the renewable energy sector in the UK.

Having seen its lead in onshore wind turbines disappear in the 1980s, he says the country must not repeat the mistake with offshore wind.

The company has invested heavily in wave power but, without an indication from the government, Mr Bettison says the sector will not take off, as other investors will hold back. Unlike nuclear, tidal and wave power is an untested technology.

The Labour and Liberal Democrat parties promised “green investment banks” that might fund such schemes. But the political uncertainty caused by the coalition between the Conservatives and the Liberal Democrats could mean the impetus for tidal power is ebbing.

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