Proposal
Introduction
Since COP26, there is widespread agreement that all the energy we consume in the UK must be from non-fossil fuel sources by 2050. However, the present trajectory for decommissioning coal-fired power stations along with ageing nuclear power stations means that we are becoming vulnerable with our increasing dependence on solar panels and wind turbines. Neither can provide a solid, reliable supply that meets the needs of industry or private households.
Solar output is at a maximum during sunny days in summer when the National Grid needs it least. On a cold winter’s night, solar contributes nothing.
On calm days, the overall output from wind turbines can reduce to as little as 10% of the rated capacity which can last for up to 2 weeks.
However, Britain is fortunate in having one of the largest tidal ranges in the world in the Severn Estuary capable of generating up to 10% of the total electrical power requirement of England and Wales.
Barrage locations considered over the years. Black indicates locations of most interest together with their associated peak power generation (Image in the Public Domain).
Concept
The Great Western Power Barrage proposal envisages a concrete embankment across the Severn Estuary in which turbines are installed to generate electricity from the tidal flows in and out of the estuary.
The concept is not new. With the Estuary’s colossal tidal range and energy generation potential, similar proposals have been put forward in the past.
A barrage across the Severn Estuary will provide 100% reliable and predictable power from the tides to give certainty in forward planning. With a tidal range up to 15m, it will provide a colossal 8-15 GW - equivalent to electricity from 500-1000 of the world’s largest wind turbines or from 16,200–30,400 hectares of solar panels. It will provide at least twice as much energy as any other UK power plant.
The difference today is that the UK is now actively seeking to reduce its use of fossil fuels - coal, oil and gas - and is turning to wind and solar as replacements. However, the output from these replacements fluctuates since it is weather dependent. A barrage across the Estuary is the only realistic means of providing a reliable renewables base load for the economy - without it, and as the amount of wind generation increases, the larger part of the available supplies will become more precarious. As well as having limited output during wind droughts, severe storms with high wind speeds have led to wind turbines having to be shut down as happened in South Australia in September 2018. Even if there can be compensation for this unreliability by hydrogen generation or using battery storage at critical times (with the UK’s ambitious carbon targets and advancing electrification of the economy) there is still an inescapable need for additional electricity.
A second and no less important difference is the increasing awareness of the effects of climate change. Large areas around the upper Estuary including the main population centres at Cardiff, Newport and Bristol as well as the Somerset and Gwent Levels are expected to flood more frequently.
Our proposal
Our proposal is for a barrage extending from Lavernock Point (just south of Cardiff) to near Hinkley Point (Somerset). This barrage embraces more of the Estuary to increase the amount of generation available by comparison with the earlier alignment from Lavernock Point to Brean Down. At the same time, it will protect the Somerset Levels from a repeat of the catastrophic flooding in 2014.
Indicative alignment for the Great Western Power Barrage
The benefits
Provides base load electricity to reduce the UK’s dependence on the more expensive nuclear power as well as on imported energy from sources not under its control.
Protects the estuary upstream from flooding during extreme tides and from the expected rising tide levels caused by future climate change.
Benefits the environment by re-establishing salt marshes as waterfowl habitat and reducing erosion caused by tides and waves.
A complete solution
There may be concerns over the carbon cost of the build, the loss of inter-tidal mudflats, interruptions to fish migration and access to upstream ports. However, each is capable of mitigation and indeed there are offsetting benefits. In any event, these need to be judged against the disadvantages of the alternatives, given that we must generate or find more electricity from somewhere.
The Team promoting this barrage are strongly committed to working together with the local authorities on either side of the estuary as well as with industrial partners to harness this gift of nature to benefit us all.
The barrage will be built using proven technologies. The aim for the barrage is to maximise the use of local supply chains and to enhance the economic future of the whole region. It is to provide a source of energy sustainable for future generations whilst contributing to the UK’s Net Zero targets.