Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Letters: Tidal lagoons – how refreshing

swansea barrage

Tidal lagoons: Exciting prospect or non-renewable threat to the planet?

Your article on Tidal Lagoon Power’s progress with plans to develop a portfolio of tidal-powered electricity generation stations was a breath of fresh air (NCE 12 March).

Refreshing both because the enterprise has been promoted from within the engineering industry and because it harnesses the only near 100% guaranteed reliable and sustainable energy source available in the UK.

It’s been a no-brainer waiting to happen and we must ask why it took so long to gestate.

It not only generates, it’s inherently low carbon, creates no hazardous waste or emissions, provides a recreation facility, does not require any public funding and is an essentially productive enterprise.

May there be many more!

  • Philip Morris (M Retd)

The generation of electricity from the second highest rising and falling tide in the world through a 70km2 tidal lagoon off the coast of Cardiff is an exciting prospect.

Design engineers will I am sure not lose sight of the huge volumes of Severn Estuary silt that will be collected in such a lagoon and the maintenance provisions that will have to be made to remove the accumulated material and the additional wear and tear that silt laden water will impose on the turbines. Not insurmountable problems but these are issues that are not likely to be as severe at the Swansea Bay scheme, which is apparently being used to answer a lot of the technical and environmental questions for Cardiff.

My own experience of tidal accumulations of silt in the Bristol Channel come from works undertaken at Avonmouth and at Sharpness, admittedly a little further up the estuary, but the mud flats exposed at low water in Cardiff Bay and at Weston-Super-Mare tell their own story.

  • John Laverick (F Retd),

In his Comment Mark Hansford suggests that industry may have a cynical view of “genuinely renewable energy such as tidal power” (NCE 12 March). I believe the situation may be simpler than that. It is quite possible, to borrow a quote from Benjamin Disraeli, that the proponents of alternative energy sources have become intoxicated with the exuberance of their own verbosity; that we have detected this, and are treating their claims with the attention they deserve.

For example, the FAQs section of Tidal Lagoon Swansea Bay’s website states that “Renewable means that the tide, and therefore the possibility of generating energy using the tide, will not run out”. This statement, and others like it, is not only wrong but also disingenuous.

Without us extracting any energy from the tides the frictional losses are reducing the Earth’s rotation rate (about 2 milliseconds/century) and, as a result of conservation of angular momentum, the Moon is retreating from the Earth (at about 40mm/year). The Earth loses rotational energy at a rate of about 3.1 TerraWatts.

Our current global energy consumption has been estimated at ~1022J/year or about 100 times the annual loss of the Earth’s rotational energy, and ~10-7 of its total rotational energy. At this rate of energy loss the Earth will keep spinning for millions of years. Tidal energy schemes act like additional friction. It is estimated that the Swansea lagoon will generate ~2 x1015J/year, so it would take about 50,000 Swansea lagoon schemes or their equivalent to create an effect comparable to the tidal energy losses due to friction.

This level of energy extraction is just conceivable at a global level, particularly given future improvements in energy extraction efficiency. Thus, while it is fair to say that the resource is plentiful it is not true to claim it is either renewable or sustainable in the normal sense of the words.

Tidal power schemes are not renewable. They will extract a small amount of energy from a large but finite pool, namely the Earth’s rotational energy.

With a little more clarity and honesty in the description of their wares, the proponents of “renewable” energy schemes might better engage those who appreciate the laws of physics which, as physics A-level is a prerequisite for accredited engineering courses in the UK, should include the UK construction industry.

  • Professor Dominic Reeve (F)

Advocates of renewable energy are always reluctant to acknowledge the intrinsic ­variability of renewables. Tidal Lagoon Power proposes to resolve the daily tidal cycle by creating a series of lagoons around the coast; but we still have the monthly cycle.

They will presumably make the most of spring tides, so there will be a need for back-up capacity (fossil-fuelled?) to make up the difference during neap tides. This back-up capacity will inevitably be idle for much of the month.

We can welcome the contribution of tidal power, but the overall costings and the strike price should recognise the idle capacity.

  • Mike Keatinge (M), Highbank, Marston Road, Sherborne, Dorset DT9 4BL


When gender quotas skew the other way

I was dismayed to see you going on yet again about gender equality in your piece on the Tideway Tunnel contractors (NCE 5 March).

The pool of female civil engineers is determined by the output from universities over three or four decades.

If high-profile employers achieve their absurd near-term targets for numerical equality between male and female engineers, this can only be at the expense of greater inequality in other workplaces.
Industry leaders (and leader writers) should get down from their podiums and focus on the laudable efforts to promote engineering to girls in schools.

As Richard Hein points out in the same issue, this issue is two-sided. My daughter recently graduated from a psychology course on which around 90% of the students were women. She is now doing a clinical masters course on which all the students are women.

I fear for the future job prospects of my daughter and of Mr Hein’s wife (not to mention more than 300,000 nurses) if masculinists start calling for gender equality in the NHS.

  • Hugh Morrison (M)


Don’t give voice to unfortunate points of view

It is an unfortunate part of industry that some people will hold viewpoints such as those of Richard Power in his “Equality of the Sexes” letter (NCE 12 March).

However, to give them a platform is even more concerning and hence my surprise that you chose to
print it.

Among the many flaws in his letter, the most profound is his misunderstanding of the issue. We are not equal in our characteristics, no two people are, but we are entitled to equality in our opportunities.

If Power is a member of the ICE then I would consider whether he has breached Rule 1 of the Code of Conduct: “Members must treat all persons with respect and without bias”.

And finally to Godfrey Ackers, the writer who congratulated Power on “raising his head above an excessively high parapet” (Letters last week)- that parapet is the law.

  • Rand Watkins (M)


Women are not only minority

Your editor’s note to Tom Patterson’s letter seeking suggestions for who should become the second female ICE president (NCE 19 February) surely attracts the answer of the best person available seeking that office.
The letter suggests artificially skewing the election process to ensure that we have another female president.

At first sight, the suggestion has some merit but denying the best candidate for any position the role they deserve because of perceived prejudice is a flawed strategy. Women aren’t the only minority among our membership.

  • Bob

Main point: HS2 must face up to serious questions

Curzon Street HS2

High Speed 2: Time for a review?

You ask for “the right questions” to guide debate about the role and nature of High Speed 2 (HS2) (NCE 12 March).

Government has identified broad strategic objectives for HS2 in the absence of a UK transport strategy. Indeed HS2, as by far the largest transport project in the National Infrastructure Plan, appears set to become the core of a national transport strategy. This places a heavy burden on project proponents to demonstrate it will be effective in delivering its objectives; for if it is not what is the fall-back solution?

Major projects need to follow a project development process that defines existing problems, identifies and compares all potential project solutions, and develops a robust business case for a preferred project that is shown to be implementable and bankable. Because forecasting uncertainties many years ahead are large, forecasts need to be underwritten by risk analyses and cogent arguments that set out why this project is the right project.

Without this there may be questions that cannot convincingly be answered and may undermine support for implementation.

Questions requiring answers and transparency about risks and uncertainties include the following:

  • Who would use HS2 (rich or poor), for what purposes and in what numbers?
  • Have all feasible strategic project options been identified and appraised?
  • Does HS2’s high design speed balance the requirements for intercity connectivity and avoiding sensitive AONB’s?
  • How would HS2 help support additional economic growth, and ‘rebalance he north-south divide’?
  • What impact would HS2 have on rail, road and aviation congestion?
  • How will HS2 fit into a private sector concession model?

What hard evidence is there that the benefits will justify the costs?

Answers should provide confidence that the right project has been identified, that it will be integrated successfully into its environment, and that it will provide good value for money - in other words that the UK is set on the right transport strategy

  • Roger Allport (F),

Peter Darley makes some excellent points in his letter about High Speed 2 (NCE 12 March). I too fear that the project is misguided and wasteful and will be disadvantageous for a great many.

I have no doubt that the railway between Milton Keynes and London Euston is approaching capacity but I am completely unable to make the leap of faith that takes this problem to the solution as proposed. The M6 is also full; would we build a relief road with no junctions to access the major centres of Coventry, Walsall, Wolverhampton, Stafford and Stoke on Trent so that traffic could flow faster to Manchester? In addition Euston is the proposed London terminus, taking away valuable capacity on the very line that it is being relieved.

What we need for Britain’s railway system is capacity, connectivity and inclusivity. The population spread in Britain is not like France and so what suits them may not suit us. Why build a line that avoids major population and commercial centres along the route taking the most circuitous route imaginable to Leeds and Manchester?

We need a complete rethink. What are we trying to achieve? The problem appears to be capacity at the south end of the West Coast Main Line. Why not build a new line to relieve this section only? Why not get the freight traffic off the line by building a freight only railway and free up lots of capacity for passenger growth? Surely there are other answers that are more suited to our needs than the vanity of running at over 300km/h?

  • David Holmes (F), 14 Sunfield Park Shrewsbury SY2 6PF

I’m with Peter Darley. It’s time we reviewed High Speed 2. My questions would be: is it a good investment for the taxpayer? Is it the best transport scheme for the corridor it serves? Are there better alternatives?
Carry on with sensible schemes such as the Thameslink programme, the Great Western electrification, and the countless improvements to railway stations. While these may be less prestigious, I have a strong feeling they are designed with the passenger in mind, with strong benefit to cost ratios, and few adverse effects.

Can we also review High Speed 3? I suggest it is put back in its box. I’m persuaded by Roger Hand (NCE 29 January) that HS3 is not the right trans-Pennine solution. His scheme, as described, appears to have clear advantages: lower cost; faster delivery; greater simplicity; and it leaves the environment intact.

  • Norman Pasley (M)

The input from Peter Darley was strong, but a bit late in arriving. The “cosy consensus” to which he refers includes our own Institution, the leader of consultants, a former government minister, plus at least one financial guru, and the Westminster Parties who will vote on it this year.

We need to distinguish between a high speed railway and a high capacity system. The only route for a true high speed railway in the UK is north east to Edinburgh, with one stop and able to compete with airways.

The currently planned “Y” route is a good enough compromise, but it should now be planned for high capacity, including junctions and major freight yards. Extensions might later be possible, for example towards the west.

The track for a high capacity system would be engineered to very high standards for abnormally heavy duty. The passenger coaches would all be double-deck and at least equal to the largest in the world. The loading gauge would be 5.6m and the overall width 3.2m. A train of 12 coaches would easily carry 1,100 seated, at a speed of 200km/h. Freight trains would carry HGV lorries in “piggy-back” at 150km/h, mainly at night. It has been the adoption of their own solution by the Department for Transport from the period of mid-2011 onwards and without any Engineer Appreciation Report that has to be held responsible for what is now likely to be an impending waste of public funds.

  • Brian Warburton (F),

I have to agree with Peter Darley that the case has not been made for High Speed 2. If the proposed budget for this project was spent on upgrading the country’s extensive existing railway network to increase speeds throughout the country, the effects would far outweigh those of HS2. There is so much to be done on the existing network - we have not even got electrification of all main lines throughout the country yet.
Robert Cattell (M), 5 Kings Mansions, Lawrence Street, London SW3 5ND

The weakness of High Speed 2 is that it concentrates on cutting a few minutes from getting from the platform in London to the platform in Birmingham. For most people that is only part of their journey. What we need is improvements in the performance and connectivity of the railways as a system to benefit a greater number of travellers.

The benefits of high speed rail are less in the most densely populated parts of the UK than in other countries because the journeys here are shorter and many of our long distance trains are quite fast already.

  • Ben Tatham (F), St Anthony, Pligrims Way, Westhumble, Dorking, Surrey RH5 6AW

I totally agree with Peter Darley. HS2 is a very costly white elephant. As Darley stated in his letter, the cry is that as other countries have high speed lines so the UK should also have them. This argument overlooks two points.

Firstly other countries have found that some of their expensive high speed lines are losing money.

I understand that is the case in France and possibly also in Spain.

Secondly the geography of several European countries is different than the UK, with much longer distances between cities and lower population densities than the UK. The case for HS2 appears to be based upon extrapolations in growth in rail ravel. Yes rail travel growth has been very high over the recent past in the UK, but will the present rate of growth continue indefinitely? Very probably it will not.

Increasing use of the internet, IT and increased working from home is likely to reduce the growth in business and commuting travel in the near future.

The civil engineering profession needs to look beyond its own self-interest and realise and then state very forcefully to politicians that HS2 is not required, and state that it is a colossal waste of money and scarce resources.

  • Deryk Simpson (M) 6 Upper Broom Way, Westhoughton, Bolton BL5 3YG

I have been waiting for someone to support my hitherto unvoiced opinion concerning HS2 and I was, therefore, delighted to read Peter Darley’s contribution to the debate. Apart from the issue as to the necessity for HS2, I do not believe that the UK can afford the currently estimated cost at a time when cuts are being made all round.

I was involved in the planning of the Channel Tunnel project from 1971 until 1991. I have great admiration for the way the late Sir Alistair Morton managed to persuade the financial backers of the scheme to support it. Had they known that the eventual cost would greatly exceed the original estimate there is no way the project would ever have been built. By February 1990 the costs had risen from the original estimate of £4.7bn to £7bn.

I raise this simply to emphasise that the likely eventual cost of HS2 would greatly exceed current estimates if we should be so foolish as to allow it to proceed.

The need for the Channel Tunnel was self-evident as an all-weather alternative to ferry crossing of the Channel, whereas no case has been made to justify HS2.

  • Arnold Aarons (F Retd),

China has a relatively sparse rail network covering great distances. Before its present high speed expansion trains were slow. Japan, though smaller, lends itself to a high speed corridor because of its linearity, and similarly offered limited speed before the introduction of Shinkansen. France too made a great leap forward with its TGV.

Britain already has three high-speed lines in addition to High Speed 1, where high speed is defined as at least 200 km/h, and arguments about the productive value of well-provided travelling time carry increasing weight.

Nevertheless, if we are committed to HS2, as seems likely, we should try to make the best of it, as well as take steps to avoid its possible draining effect towards London. And that means improving regional and local connectivity.

The call by One North last July is now echoed in the south east by Aecom (NCE 12 March). One part of connectivity is timetable integration between intercity, regional and local, including bus services, which some authors argue requires a single tactical (though not operating) authority, although an alternative may be high frequencies.

A question remains in how to achieve high speed high frequency regional connections over distances much less than the 150km considered the economical minimum for high speed rail, potentially enabling “virtual agglomeration” of population and economy.

What technologies could achieve a step-change in regional service without excessive cost or burden on the environment, taking account of probable future developments and energy sources? Switzerland’s proposed SwissRapide maglev network has stage lengths averaging around 60km and as short as 30km, but choice of technology in the North of England would be influenced by its complex and often sensitive geography and its existing infrastructure.

Determining what would be achievable by enhanced conventional or new technologies is as much an engineering challenge as it is a planning challenge.

  • Nicholas Taylor, 6 Chiltern Road, Little Sandhurst GU47 8NB

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.