Power Generation

Wave energy: In the late 1970s, the concern was that we would run out of oil by the 1990s, Few could even spell the word “environment”. Then, Christopher Cockerell, the inventor of the hovercraft, proposed the use of a hinged raft to generate energy from waves. It was calculated that with the wave climate to the west of the UK, these rafts could provide 7% of UK energy.

At the time I was working for A&P Appledore, a marine consulting company. I was attracted to this scheme and eventually persuaded government to give us £100k to evaluate the practicality of using the Cockerell raft

A highly compressed summary is that, as each raft required 3000 tonnes of steel (the steel weight of a typical 15000 tonne dry cargo ship), it would take the entire berth capacity of British Shipbuilders (as it then was); and the entire plate production capacity of British Steel (as it then was) to support the programme. It would take 25 years to build the line of rafts along the west coast, by which time the rafts first built would need to be scrapped and renewed. It would be a project in perpetuity! This revealed that the key question was the net energy balance. Taking account of the need for support vessels, social support for the workers and so on, was it worth it? Would we get more energy out than we put in? Note that in this discussion there is no mention of environment. If we took that much energy out of the wave climate, what would it do to the coast? We did not even consider that question!

Since that time, a lot of work has been done and more modern versions of wave energy generators capable of dealing with a hostile saline marine environment have been developed. Some interesting pieces of kit are installed now, especially in the north of Scotland.

Of course, waves depend on wind, but ocean swells travel vast distances and are not dependent on local winds so much. So wave generators are likely to have different periods of low generation to wind turbines.

Tidal power: In the 1990s there was a major study concerning the practicability of building a Severn tidal barrage from Brean Down to Lavernock Point (roughly Barry to Weston Super Mare) ABP had 5 ports on the South Wales coast, and both Cardiff and Newport would be inshore of the barrage (as would Bristol and Gloucester).

They key thing is that a tidal barrage, though not a continuous generator, is totally predictable, years ahead. By opening the generator sluices before high water, and closing them after low water, generating downtime could be managed and optimized. I was responsible for insisting that there should be 2 locks in the barrage instead of 1 to provide resilient access to the upstream ports.. In terms of scale, the project was significantly larger than Channel Tunnel, but would have provided several percent of the national base load requirement. It was eventually abandoned on mainly environmental grounds as the mud flats would be significantly reduced putting pressure on migrating birds. In addition to abandoning a steady source of power, the barrage would have provided a major flood defence against rising sea levels, and a significant road (and possibly rail) connection between Somerset and Wales.

The ecological NGOs and pressure groups are going to have to learn to engage in difficult decisions such as the use of nuclear power and the choice between some environmental reduction or face a massively changed climate.

Also

There are other possible tidal barrage sites, including Morecambe Bay, though none have the colossal tide range of the Bristol Channel.
There have been several attempts to put large turbines in strong tidal streams, with mixed success. The most promising, at Strangford Lough, was finally abandoned. It seems the hostile saline marine environment got the better of the engineering. Other sites such as St Catherine’s Point and Needles Channel (Isle of Wight) and the Pentland Firth have been considered. No doubt the technical problems will be mastered and unit costs reduced over time given proper funding.

Click here to return to previous page