Power from the Mersey

A giant waterwheel stretching across the River Mersey could be used to generate renewable electricity for the Northwest, according to a new study that identifies the river as one of the top sites for tidal renewable energy in the UK.

Experts say the Mersey estuary’s large tidal range of 8-10 metres and unusual shape combine to create powerful tidal currents that could be harnessed to produce power.

The waterwheel is just one option - the largest of the projects being evaluated, a tidal barrage across the river, would generate 700 MW of electricity, enough to power 260,000 homes and save 516,000 tonnes of CO2 per year.

According to the government’s energy White Paper on the country’s future energy needs, Meeting the Energy Challenge, 'Tidal power could make a significant contribution towards meeting the twin challenges of climate change and security of supply.'

Any project to generate power on the river would also be a major boost to the UK’s position as the world leader in marine renewable energy.

However, the team behind the Mersey study are keen to emphasis that a full barrage is just one of the innovative options being looked at. Much more likely option are waterwheels, tidal turbines and open stream energy converters. The report describes how the various technologies could be used along the river.

An artificial tidal lagoon could be created in the open sea beyond the mouth of the river, with the flow of water in an out used to generate power. A tidal fence would comprise vertical turbines housed in submerged cells built across the estuary. The restriction to the flow created by the fence would accelerate water through the turbines to create power. A tidal gate could be specifically designed for the shallow waters of the Mersey. The bottom part of the sluice would be fitted with a matrix of compact turbines. Finally, central reservation in the river could be created to hold a series of open stream turbines, converting natural tidal flows into energy.

Professor Peter Guthrie, Professor of Engineering for Sustainable Development at Cambridge University, an internationally recognised expert in green technologies, has been part of the study team led by consultants Buro Happold.

'The whole principle of the study is that the technologies under consideration must be proven, but they would be used in innovative new ways,' said Professor Guthrie.

'Waterwheels produce less energy than marine current turbines, but they are robust and require low maintenance. We are trying to be innovative and novel but also reduce the risk to a minimum,' he added.

'We have been searching for a way to generate renewable energy on the river that would bring jobs and investment but we must also respect the Mersey estuary’s international importance for wildlife such as wading birds,' he concluded.

The study was co-sponsored by Peel Holdings, owner of the Peel Ports, and the Northwest Regional Development Agency (NWDA).

'We are looking at the type of technologies available for generating electrical power. It has already been established that it is tidal flow and not wave power that would be the most suitable method for the Mersey. There are different schemes that could be utilised, some visible and some hidden. It may be that a scheme will be trialled initially as part of a wide consultation process,' said Tim Bownes, chief engineer at Peel Ports.

Many of the technologies being evaluated are so new that they are still under development. For this reason, the experts are likely to recommend a pilot project that would allow testing before full implementation.