In the face of global warming and climate change the need to find sustainable and secure sources of energy has never been more urgent. The UK has the potential to generate large amounts of clean and secure electricity, by using the tidal range resources concentrated in a limited number of locations, which include the estuaries off the west coast of Britain, such as the Severn, the Mersey and the Humber. A major study led by Sustainable Development Commission (SDC) [1] is currently underway and is looking at issues related to harnessing tidal power in the UK.
Of course exploiting the tidal resources in a bay or estuary is not something new. Similar plans have been working in other countries for decades. The Rance tidal power plant, located on the Estuary of the river La Rance, near Saint Malo in France, is the world’s first electrical generating station, powered by tidal energy [2]. It was installed in the 1960s and has been functioning until today, producing a considerable amount of the country’s energy need.
The SDC takes into consideration a wide range of sites and technologies. Τhe most important study concerns the installation of hydroelectric barrage in the estuary of river Severn, near Bristol, which might cover the 10% of energy demands of entire Great Britain. However, due to the fact that it would cause “irreversible damage” to the ecosystem of area, the realisation of such scheme is doubtful. One of the other potential options regards the possibility of producing maritime renewable energy in the Mersey Estuary, while allowing the region to prosper and grow.
The river Mersey is 112 km. long and it flows through Manchester and out to the sea at Liverpool. The Mersey Estuary is of great importance to the economy and the environment of the North-west and of the United Kingdom. It is a major shipping route and the location of several industrial sites. Moreover, together with the surrounding area, it is regarded as a region of archeological and architectural importance and its ecosystem is of both local and international importance. Due to its 10m difference between high and low range, its good current velocities and the river’s unusual layout, it has a great potential to produce environmentally-friendly power.
During the last couple of years a team made up of leading experts in the field of marine power generation and technology, engineering, regeneration and the environment, has been studying the river Mersey to find ways generating electricity from its tides. The project that is co-sponsored by Peel-Holdings (the owner of the Mersey Docks and the Harbour company) [3] and the North-West Development Agency (NWDA) [4], suggests that the power hidden beneath the waves of the river could be sufficient to produce enough electricity to meet the needs of nearly half a million people.
The Mersey Estuary has been the subject of number of studies in the past, looking at the potential for a tidal barrage, but none of them was progressed further. In order to harness the natural resources of the river, academics and specialists engineers have now been looking at a wide range of technologies that would have minimal impact on shipping and would avoid harming to its valuable wildlife sanctuaries. In a meeting that took place in Liverpool last June, they came up with a reasonable list of options that could be taken forward to a further more detailed study in the future.
Among the proposed mechanical systems available for tidal energy conversion were different turbine designs, including waterwheels. Potential options include power generation from turbines that could be housed in large cylindrical structures positioned within the Estuary, although not necessarily extending right across it. An option unlikely to be considered is the development of a full scale barrage across the river, since it has been restricted by concerns over cost, shipping and local environmental impact. Many of the technologies evaluated are so new that they are still under development. As a result, the experts are likely to recommend a pilot project that would allow full implementation.
However, it has been proven that all tidal technologies have a number of environmental, social and economic impacts that need to be considered [5]. Environmental concerns in particular are quite forceful. The disruption of the area and the risk of pollution to the river from this kind of structures, are a cause of great concern, although once up and running, this form of generating electricity is quite safe to the environment. As a result, in order to select the best tidal power scheme for the Mersey Estuary, several tasks need to be undertaken as part of future studies. These include:
- Preparation of outline designs for the associated civil engineering works,
- Modeling to determine power predictions and generation performance,
- Calculation of overall construction programme and cost estimates,
- Environmental impact studies,
- Modeling to determine the impact on tides and sediment movement.
Unfortunately it will take many years to discover whether the idea of generating power in the River Mersey will progress beyond the computer animation stage. Estimations suggest that it will not be before 2010 until they get around to putting any application and at least another decade after that, before any scheme on the Mersey will be implemented. But if the scheme does proceed and the tidal resource of the river is fully exploited, large quantities of low electricity could be produced to cover the demands of a city as big as Liverpool. Such projects therefore deserve particular consideration and should be looked into carefully, since they can become part of a much wider action, aiming to tackle the twin challenges of climate change by reducing carbon dioxide emissions and ensuring secure, clean and affordable energy.
Potential for associated economic development/ regeneration studies.
vasiliki.pappas@liverpool.ac.uk
- The Sustainable Development Commission is the Government’s independent advisory body on sustainable development.
- Tidal energy exploits the natural ebb and flow of coastal tidal waters. The currents flowing in and out of these basins can be exploited to turn mechanical devices to produce energy.
- Both Peel Holding and the Mersey Docks have been involved in the renewable energy sector for some time, mainly in relation to landfill gas utilization and small-scale hydro-electric schemes.
- The North-West Regional Development Agency is one of the nine regional development agencies established by the government to develop the English regions.
- The barrage of La Rance for example has caused progressive silting of the river’s eco-system. Sand-eels and plaice have disappeared.
LINKS
