Select Committee on Science and Technology Minutes of Evidence

Memorandum submitted by Professor S H Salter, Department of Mechanical Engineering, University of Edinburgh

  This note follows the list of questions in the call for evidence of 11 January 2001 with the addition of material on research facilities. The call specifically restricts evidence to non-barrier tidal schemes using the kinetic energy of the water velocity rather than the potential energy as used at La Rance and proposed for the Severn.

Is the technology available for efficient generation from waves and tides?

  The technology is not yet mature for either but the specifications for hardware are well understood, full-scale items for wave energy are being tested in commercial size prototypes and the time for efficient generation is not far off. Pilot tidal stream projects funded by the EC are under way. As in every other technology the efficiency will improve continuously as designs and manufacturing evolve, so there will not be a sharply defined moment.

Will wave and tidal stream energy become commercially viable in the near future and attractive to the private sector as a profitable investment?

  Commercial viability is difficult to define for renewable energy systems. With information about wave climate from the meteorologists and fluid loadings from tank tests we know exactly what the weight of the plant will be for stresses that the insurance market will accept. But the cost of a component as a function of weight is a carefully guarded commercial secret and jobs would be lost if accurate figures were to leak. Estimates for capital cost are therefore based on uncertain parametric figures which could easily be altered by some change in manufacturing process, for example an increased level of automation for welded fabrication or the reuse of concrete shuttering. The change could be by as much as a factor of three or more, as has occurred with wind. It is also hard to compare new installations with nuclear stations which were brought by their present owners on rather favourable terms when electricity was privatised.

  However, an even greater uncertainty is because the costs of electricity from renewable sources are completely dominated by variations in the interest to be charged on the initial capital investment. Rates can range from the 15 per cent used for assessing some UK proposals down to 0.5 per cent for money borrowed in Japan. This range of 30 to 1 feeds directly into costs per kilowatt hour. AEA Technology are to be congratulated on the recently introduced practice of plotting costs of renewable sources against assumed interest rates.

  The only practical tests of commercial viability are the reducing level of subsidy needed to make private investors build new plant and the continued solvency of the companies involved. Wind turbines are only now just starting to be installed with no form of subsidy or tax relief. Even though there were six million wind-turbines in use for water pumping in the United States at the start of the 20th century and the aircraft industry had established the necessary theory to a far higher level than was available for waves in 1973, it has taken 27 years and several billions of pounds for wind generation to achieve this break-through.

  It would be reasonable to expect a similar period for both waves and tidal-stream unless special and unpleasant circumstances force a more rapid process. However, several investors are risking their money for research installations and several research groups are investing something more valuable to them than money—their working lives—because of the belief that commercial viability will eventually be achieved.

What projects are currently running in the UK and how successful have they been? Why did past projects fail?

Tidal streams

  The Committee will be taking evidence directly from people more closely involved with their own tidal-stream projects and I am hesitant to make comments on the work of others. Two groups in Britain are led by Peter Fraenkel and Ian Bryden and funded by the EC. Both are working on pile-mounted tidal-stream generators using the horizontal-axis rotors. The horizontal configuration has proved more successful in wind energy than the vertical-axis one. Indeed the operation of the plant now being built will be very like that of an underwater wind turbine with dimensions modified for the much greater power density. The sizes that have been chosen are sensible for initial experiments. The rotors are sufficiently far below the surface to reduce wave loading.

  My own tidal-stream work has been concerned with paper studies and design calculations of a vertical-axis scheme (tried but rejected for wind) using a ring-cam power conversion mechanism developed initially for wave energy. The figure shows an artist's impression.

  The reasons that the vertical axis did not succeed for wind were that it uses symmetrical foil sections which have a slightly worse lift-to-drag ratio than asymmetric ones: that the blades are subject to reversed fatigue loading; that each blade had to pass through an idle point twice per cycle; that rotors with only two blades produced a very uneven torque.

  A vertical axis tidal stream rotor will have about 10 sets of blades so that the torque is smooth. The provision of variable pitch reduces the fraction of idle time. Buoyancy cancellation of weight encourages the use of thick foil sections, which can be made strong enough to resist fatigue.

  The main attraction of the vertical axis configuration for tidal-streams is that the rectangular profile can fill a large fraction of the flow window with closely-packed rotors and so can make better use of the available resource. The ring-cam is at the full rotor diameter so that torque-related stresses are not magnified by sending power to a reduced radius. Surprisingly, the large diameter of the cam makes it lighter because every cam roller is operated by every cam lobe. All the power conversion mechanism can be in a relatively spacious compartment above the surface and much of the sealing problem vanishes. However, the vertical-axis scheme is much more vulnerable to wave loading. This will require very careful tank testing in every possible combination of wave and current direction and there are at present no facilities for combined wave and current tests. Siting of vertical-axis rotors will be restricted to the more sheltered channels rather than the exposed headlands. Rotor diameters sufficient to provide the necessary stability in pitch and roll would have a power rating of 10MW or more so that the vertical-axis is not a candidate for early sea trials.

  An interesting feature of closely-packed turbines is that, if the ocean forcing function and acceptable upstream water levels allow, they can improve on the Betz efficiency limit for open field flow by blocking the channel and increasing the upstream head. This could be controlled so that units always operated with flow rates of spring tides through the entire lunar month.

  The design calculations and an estimate of electricity cost have been carried out by AEA Technology at Harwell (report AEAT 3517). More details appear in the attached pre-print of a paper to be given at the Marec 2001 conference in March,

  An indication of previous commercial viability of tidal-stream technology is that many thousands of tide mills, consisting of an undershot water-wheel mounted on a pontoon, were in operation in medieval times. The modern programme has not been running long enough to have had any failures. Tidal-stream turbines will not achieve the high efficiency of barrage systems but the investment is made in much smaller steps. The predictability makes the resource attractive to the electricity market.


  The first UK on-shore oscillating water column, built at Islay by Queen's University Belfast, has now been deliberately demolished, leaving almost no trace. Although it had a very low power rating it can be regarded as a considerable success if only through its survival.

  A second, larger, offshore oscillating water column, the Osprey, planned for installation by Applied Research Technology off Dounreay, was destroyed by heavy waves during the installation. The Committee will be interested to hear that the silt on the recovered parts was so radioactive that it would have been illegal to store it in an open laboratory. I believe that the root cause of the failure was ultimately traceable to inadequate tank testing. I was relieved to hear that the company has since acquired its own wave tank.

  Lessons learned from the first Islay plant and from Osprey have been incorporated in the Queen's University/Wavegen Limpet, a full-size onshore system built close to the site of the smaller one. This was connected to the grid at the end of 2000 and is now undergoing trials at levels limited by an undesirably meagre grid connection. I am sure that the Committee will be hearing directly from Professor Whittaker and from Wavegen Ltd.

  The early installations of wave power devices have shown that a well-chosen wave site is a poor construction site and I expect that there will in future be a move toward yard construction and floating devices. All the people involved with onshore plant agree that eventually, and perhaps quite soon, the installations must move offshore because of high power levels and more sea space. The next move in that direction is to be made by Ocean Power Delivery led by Richard Yemm. The company has built a series of models of the Pelamis system at progressively increasing scales. A full size unit will be launched next year. They have a 15 year SRO-3 licence to operate two 375 kW units at Machir Bay on Islay.

  The Pelamis produces power by hydraulic pumps at the joints of a segmented spine lying parallel to the wave direction. The company has placed particular emphasis on survival rather than on productivity or best use of sea space, but the combination of rigorous tank tests and numerical computer models has produced a very creditable power-to-weight ratio—quite as good as that of larger systems. It has been Richard Yemm's policy to use no material or component that does not have an established track record in offshore conditions. The programme will provide a great deal of information about the use of hydraulics for wave energy.

  A final wave scheme using wave overtopping with a free-floating vessel, developed by Sea Power International, has been awarded a SRO licence to generate at a site off Shetland but I am not close enough to the project to make any comment.

  As part of an EC JOULE programme the Edinburgh group designed and built parts for a turbine and a fast control-valve to be used in a Portuguese oscillating water-column in the Azores. Low-pressure air has been the preferred power conversion medium and the Wells turbine the mechanism. However, the Wells turbine does not have a very wide bank of efficient operation in real sea conditions because the blades stall at higher air flows. Our task was to build a variable-pitch version of the Wells turbine so as to prevent stall. The withdrawal of the commercial partner responsible for making the turbine blades has meant that the machine has not yet been commissioned. Our Portuguese partners, Instituto Superior Technico in Lisbon, hope to raise money to finish the blades and then install the variable-pitch turbine alongside a fixed-pitch one. The question about whether or not the extra complexity of variable pitch outweighs the smaller sizes, lower idle losses and increased productivity will be known when the first full-power efficiency data are available from the Limpet. This should be very soon and I would not like to predict where the balance will be.

  If I had to supply reasons for the failure of the first UK wave programme I would cite over-optimism, the attempt to make very big (2GW) power stations and to assess infant devices too quickly. The programme was properly supported and enthusiastically led from 1976 to 1983, a period of only seven years, and then entered a very unhappy phase where researchers felt that they were always on the defensive. An account of this has been given to a Committee of another place (HL paper 88, 21 June 1988 page 178 and 190-206) and it does not, at present, seem helpful to repeat it here.

What role should wave and tidal stream energy have in the Government's renewable energy strategy? Should they have a higher priority?

  This must depend on whether the Government and its civil servants really want renewable energy to succeed or whether they want to appear to be supporting a programme but really want it to fail. Over the years many of the officials with whom we dealt certainly seemed to want success but this often proved to be a dangerous career move. I must warn the Committee that this danger is not confined to officials. There was a Commons Energy Committee which looked into renewables in 1992. A copy of my evidence (pages 62 to 68 of volume III) is attached. One of the Committee's recommendations was the resurrection of the wave energy programme. The Energy Committee was immediately disbanded!

  Always there seems to be a layer, or indeed layers, of senior people with negative views about renewables and the power to make them stick. This power seems to be inversely related to technical knowledge of the subject or technology in general. If the concerns about carbon levels, global warming and long-term supplies of fossil fuels are well founded, then the Government policy should be that every possible renewable source should be thoroughly researched to the point that it could rapidly be employed at some stage in the future. The demonstration of this capability would do much to limit the dangers of a manipulated market for oil or gas and could be regarded as part of a nation's defences. The costs of a vigorous research programme are very small compared with the total spending on fuel or the possible future consequences of having insufficient energy supplies. The spin-off in unexpected directions has, so far, been quite sufficient to justify what has been spent. Diversity between renewable sources with different availability reduces the problems caused by lack of firmness of supply. This could be further reduced by the use of renewable sources for the manufacture of hydrogen, methanol, ammonia or even potable water.

  Wave energy has an enormous potential for Europe particularly if, in future, we build a spur north-west from Cape Wrath. This is discussed in an attached memorandum written at the request of the EC DG XVII Small Hydro Strategy meeting. Tidal-stream energy is smaller but attractively predictable. Both are clean and have rather low conflicts with other human activities.

What research and development is being undertaken at present?

  My own present research work on waves (initially privately funded but now supported by DTI and EPSRC) involves a modification to a Swedish buoy system which makes it move along an adjustable slope rather than in the conventional heave direction. The buoy uses an internal reaction reference and has an ingenious stroke-limiting technique which gives it outstanding survival features. The slope idea has been shown to be very good with models constrained to run along a fixed guide rail. Slope gives productivity gains of four in long period waves. Our present task is to see if this remains true for a free-floating tank model. If so, a full scale device would be suitable for power generation in very deep water. The programme has recently come under threat because of a decision by Edinburgh University to demolish our test tank this July because the land is needed for other purposes.

  Most of my previous work on waves was for the duck system. This was intended to make the very best use of the sea-space by employing large numbers of close-packed devices and using every hydrodynamic trick to improve efficiency. Official analysis of the cost of duck electricity fluctuated wildly depending mainly on assumptions about reliability and was often the highest or the lowest of the many devices being assessed. The full historical list of official cost estimates is given in an attached paper, written for an IEE conference.

  For the 2 gigawatt duck design we had taken the opposite approach from Richard Yemm. We wanted to maximise the use of the available sea space. This meant that every part had to be optimised for its task and we found that many of them had to be invented. Some of the consultants employed by Harwell to assess our work reacted just as the Wright brothers would have done to drawings of a Boeing 707. However, since the closure of the first UK wave programme, we have found ways to exploit the new technologies in other applications with support from Denmark and Canada. The duck will go to sea when it is thought that there is not enough sea space and there is a need to use as much as possible of it. I do not think that the duck programme failed, merely that it will be long delayed. If the first UK wave programme were to be judged on the output of essential wave energy theory and talented young engineers, many of whom are now in senior industrial positions, I would judge it to be a great success.

  I understand that an official from EPSRC, who has better information about the whole picture of academic R&D will also be giving evidence to your Committee.

How much funding is available and how easy is it for innovative ideas to gain support?

  Again, EPSRC will be giving evidence.

Is national funding being well co-ordinated?

  Several factors make co-ordination difficult. Private investors must protect their investment by secrecy in a way that is totally foreign to academics, even if a large fraction of the money is coming from public sources. There are even stronger motives for secrecy following poor productivity or the loss of a prototype. Mistakes will then be repeated by others. It does not have to be like this. Following an aircraft accident there is a very expensive investigation with the most detailed information supplied to and carefully studied by the entire industry. This should be an obligation in return for receipt of public money.

  A strict direction by DTI would tend to violate the independence of the EPSRC. This independence is important because there is also documentary evidence that an official from ETSU tried hard, but apparently without the approval of DTRI, to discourage support for wave energy from Brussels. Over-strict co-ordination stifles original ideas. I am, therefore, on balance in favour of open published consultation between independent bodies and a degree of anarchy. However, this general view has been suddenly challenged by a serious co-ordination problem concerning test tank facilities which I would like to draw to the attention of your Committee. It concerns test facilities for wave energy research, which I regard as essential and which are expensive enough to have to be nationally co-ordinated. I discuss this further in the section on research facilities on page 11.

What sort of peer review processes are being undertaken?

  During the "seventies and eighties" funding for almost the entire renewable energy programme of academic and industry was supplied by the DTI (or Department of Energy when it existed) through the Energy Technology Support Unit at Harwell, then part of the United Kingdom Atomic Energy Authority. Now (with many of the same people in the same buildings but a changed arrangement of fences) this group has been renamed as AEA Technology. I do not know if any peer review process was involved but I expect that everything was decided by ETSU and the Department of Energy, with long range control of a committee known as ACORD that was recruited largely from the nuclear and the depletable energy industries. It has not been possible to get minutes of their meeting of 19 March 1982 from which the wave programme manager, Clive Grove-Palmer, was excluded and at which it was decided to close the UK wave programme.

  The previous Science and Engineering Research Council funded some of the projects but nobody could understand the reasons for the separation. This has now been changed. I am told that my own grant from DTI is the last to be given to a university. From now on, only industrial work will be supported by the DTI on a shared cost basis so that industry must find some of its own money or do some very creative accounting on its overhead rate. Nobody in renewable energy can yet do this nearly as well as the defence industry.

  Funding for most academic work, now including waves, is the responsibility of the Engineering and Physical Sciences Research Council, which is given money by Government but notionally makes independent decisions. I have some evidence that this independence was not complete when, in 1986, a proposal for work on wave energy was rejected on the grounds that it was not strategic, as defined by the Renewable Energy Advisory Group set up by the DTI.

  There are two modes of application. In the responsive mode, any academic can propose any research topic in any field and it will be directed to the most suitable section of EPSRC. The chances of success are about 30 per cent. For the second managed mode, with a slightly higher chance of success, EPSRC issues calls for research into particular areas such as renewable energy and University teams can apply before the given closing date. Schemes exist for applications from young, newly-appointed staff and for decisions about projects below £60,000 to get quick decisions. I strongly approve of these. For larger projects in both managed and responsive modes, copies of the grant proposal consisting of six pages and a computerised form are sent to three or four experts in the field, one of whom will have been picked from a list of three provided by the applicant. Replies from the experts are considered by a panel of about 15 people with a general engineering background. The panel will have been drawn from a college nominated by fellow academics. Two of them will have been asked to study the proposal in detail beforehand but others may be seeing it for the first time at the afternoon of the meeting.

  Sometimes the panel will decide about an award in a way which goes contrary to the indication of the referees' comments. Sometimes they will approve a proposal, but the Council will not have sufficient funds to make an award. It used to be the case that a reduced award would be offered but then everybody increased their cost estimates by the expected reduction factor and so that has now been changed. Grants are given in full or not at all: if you put in extravagant estimates you reduce your chance of success.

  EPSRC give useful guidance on how to write proposals and the computerised forms, which do some of the calculations automatically, are appreciated. These forms are not nearly as complex as those for a DTI or an EC project. Success depends greatly on the choice of referees and the author of an unsuccessful proposal is often angry about the ignorance and even carelessness that is sometimes shown. A particularly valuable recent change is that the applicant now sees referee comments before the panel meeting and is given the chance to reply to them. I understand that EPSRC do remove from their list of referees those who appear inadequate or biased.

  Everything seems very slow to somebody with a hot idea and a research team to feed. A particular subject area (not of course renewable energy!) can develop a small charmed circle which protects its own interests, awards itself money and seeks to exclude newcomers. Except for getting international referees who will be less likely to know the applicants it is difficult to see how this can be avoided.

  The EC grant process goes to very great lengths to prevent fraud. The identities of the expert advisers are kept secret. The first half of the process uses forms which conceal the identity of the proposer. Experts are summoned to Brussels where they are kept secluded for an intensive week of appraisal so that their work rate can be observed by officials. There seem to be many fewer of these officials than for the DTI and all those that I have met have been very well qualified technically as well as distinguished linguists. EC projects require a combination of partners across European borders. This does form European bonds but it remains true that if you want to make something that is already difficult even harder, do it with people who speak different languages and who are a long way apart.

  The extreme efforts made to prevent corruption do slow the procedure to the point where it becomes very difficult to keep small companies and research groups intact through the gaps. It might be useful to calculate the ratio of money spent preventing corruption to the amount of money lost by it. I would prefer to have more severe penalties but less delay.

  The Danish support for new wave projects is in extraordinary contrast to all the others. They want to be certain beyond all reasonable doubt that every potential idea is given the very best chance to survive and prosper. Anybody with an idea for wave energy conversion is given the Kroner equivalent of £5,000. It does not matter if the idea seems bad. It does not matter if it has already been tried and failed several times before. It does not even matter if the inventor is Danish or not. They have set up a small-scale test site at a fiord at Nissum Bredning in North Jutland with a pier, power-supplies, data-logging, analysis software, shelter, hand-tools, moorings and wave gauges. Anyone who turns up gets the money and can, literally, dive in and get to work.

  Inventors of devices which show the slightest degree of promise are then given larger amounts of money for tests in the controlled conditions of university test tank facilities. The enthusiasm of everyone and the rate of progress is impressive. It is easy to see how a country which had no aerospace programme has come to dominate the world wind industry. They have yet to learn some of the lessons from the wave UK programme but I do not think that this will take them long.

  The problems of maintaining continuity for small companies and research teams are discussed in the attached notes for the DTI through a study conducted by Ove Arup.

What are the environmental aspects of wave and tidal stream energy, particularly for marine life? How will such devices affect shipping?


  The environmental aspects of wave energy appear to be surprisingly benign. The onshore devices are built into cliffs of sharp rock; where the water is deeper it is nearly always too dangerous for leisure activities. It is quite wrong to imagine ugly obstructions in the middle of beautiful bathing beaches. The concrete of onshore installations quickly matches the rock around it because the same weed and lichens are growing. It is quite difficult to see an installation from a short distance offshore. Some designs of air-turbine may produce unpleasant noise which could well be audible above the background of wind and breaking waves.

  For offshore devices the problems seem even less, and several effects are positive. Any part of a wave plant which is not in contact with the wave is not generating useful work and so many designs show very little above the surface, some none at all. Lights and radar reflectors will have to be added but the visual intrusion to people ashore will be low. They will be better marked than moving sand banks and submerged rocks and should have a net positive effect on marine safety though improved navigation markers. Cargo ships usually keep to the shortest great-circle routes between ports which are well away from the Irish and Hebridean wave fields.

  There will be more of a conflict with fishing activities. Fish like being near wrecks and oil platforms, perhaps because they get food and protection. Fishermen know this well and get as close to oil platforms as they dare. Clams grow fatter from the warmth generated by undersea electrical cables, and clam-dredgers will deliberately work along the cable routes causing a large fraction of marine cable failures. Quite apart from the risk of collisions, fishing gear can get fouled by invisible parts of mooring systems. It would probably be best both for wave energy and, in the long term for the fishing industry itself, if a strip of sea either side of a wave installation was designated as a fish-breeding reserve and strictly protected. A consolation to fishermen is that the skills, courage and endurance need for their present trade would be very much in demand for the installation and maintenance of offshore wave energy devices.

  Behind a large offshore installation there will be a tendency for growth rather than erosion of beaches but the magnitudes of the effect are not yet known. In moderate conditions the sea behind a close-packed wave plant will be noticeably calmer and so would add to the many attractions of sailing off the west coasts of Scotland and Ireland.


  The environmental impact of tidal stream plant will be greater than for offshore waves because the highest currents are in channels and headlands close to shore. There will be conflicts with shipping and perhaps concerns about the wake vortex on small sailing vessels.

  Seamen are used to all sorts of marine hazards and usually prefer them visible, so the vertical axis rotors may have some advantage. Installations can be marked on charts more accurately than moving sandbanks. They can carry lights and radar reflectors and will not make any sudden manoeuvres. They do not carry dangerous chemicals or explosives. We can expect that tidal stream plant will be less of a hazard to ships than natural hazards and other ships.

  Marine creatures have to develop skills to avoid fast-moving attackers. There is therefore reason to hope that fish can use the pressure field around the foils to avoid them. The blades will move in a very predictable way with velocities lower than the fastest marine predators. There are no reports of fish being killed by going through the turbines of the tidal barrage turbines at La Rance or by waves on sharp rocks.

  Operators of tidal stream plant will have their own very strong incentives not to spill oil, and the oils used will be light and clean.

  Marine fouling on hydrofoils will induce a serious drop in efficiency and some anti-fouling paints are highly toxic. This will probably be the environmental factor of greatest concern but concentrations will be much lower at good tidal stream sites than in the confined conditions of a yacht harbour.

How does Britain compare with comparable nations in R&D in this field? What projects are currently being undertaken abroad and how successful have they been?

  Britain enjoyed a dominant position in both the theory and testing of wave energy during the first programme but this has faded since the mid-eighties. It was difficult for overseas governments to believe that, if wave energy could not work in the good wave climate of the British Isles, it might still work for them. It took a considerable period for their local groups to counter negative reports from here.

  Enthusiasm for waves is naturally influenced by local wave climate and so is strong in Portugal and Ireland. However, the less attractive wave climate of Denmark does not diminish their enthusiasm. I am most familiar with work in Portugal, which was built up a very effective group working on oscillating water columns as part of multination European projects. The construction of the full-size unit at Pico in the Azores was delayed by incomplete civil work for two winters in succession. Damage to the half-finished structure during winter storms was serious. It was difficult to decide whether to complete the civil works or abandon the project but finally it was completed and a fixed-pitch turbine has been installed. The Portuguese have learned how expensive it can be to work so far from an industrial base and their next oscillating water-column will be on the mainland.

  The Committee will be able to obtain better information about overseas work from Tom Thorpe at AEA Technology. Following the publication of HL paper 88, 21 June 1988, Thorpe was appointed to carry out a review of wave energy. At that time the confidence of the UK researchers in ETSU and the DTI was at rock bottom. Even though some of Thorpe's early cost estimates were above the previously disputed ones from ETSU consultants, the fairness and transparency of his analysis completely reversed the attitudes of the research community. One extraordinary change was that, instead of the ban on communications between research teams and assessors which had been imposed by Harwell, he supplied copies of his spread-sheets to all the research groups. This allowed them to see where the problems were and what should be done to remove them. His reputation spread through the world wave community, leading to a number of overseas device assessments, and he therefore has an unrivalled knowledge of the subject. I very much hope that AEA Technology will allow him to give evidence to your Committee.

  Work on tidal streams is proceeding in Norway, Italy and China. The Chinese have many sites between islands and the mainland where currents are particularly strong and where supplies of new power are urgently needed.

Research Facilities

  A central part of wave energy research at Edinburgh has been the testing of models in tanks. I believe very strongly that safe and cost-effective designs can evolve only through the most rigorous measurements of the behaviour of small-scale models in controlled and repeatable conditions. It is possible, for example, to generate exactly the same 100 year wave every 30 seconds with the model position changed by small amounts. My views are also shared by leading authorities on numerical simulation of wave behaviour, which has improved greatly in recent years but is still limited to linear conditions. There are several examples of seemingly intractable problems solved after a theoretician saw a wet model under test. My work on wave tanks may now have to come to an end for reasons which should be of concern to your Committee. It is important to realise the difference between tanks for wave energy and those that were used for towing ships.

  Test tanks were originally built to improve the design of ships by reducing drag and also for accurately predicting the propulsion power that a full shape would require. There was not much variation between experiments and the time and cost of the test could be accurately predicted. A new hull could be checked in an afternoon. This also tends to be true for work on oil platforms where the main requirement is for insurance purposes with observations of fluid loading and over-topping in a set of specified extreme conditions.

  Initial work on wave energy can be done in a narrow tank with a single wave maker but even at this stage devices have to be tested for productivity with a wide range of amplitudes and periods as well as in rare extremes. Furthermore, there are many more variables of shape, immersion, trim, power-conversion technique and reaction stiffness so that, even with highly automated testing, many hundreds of hours are needed. Things get still more demanding for devices which must be tested in a wide tank with all the variations of wave direction and spectral shape.

  In 1977 we were given permission to build a new and initially controversial design of wide tank which had control of directional spectra over a wide area and wave makers that could absorb energy reflected from models. The control unit and safety interlocks were planned to allow visitors to use everything themselves and we routinely allow access to undergraduate students. It was soon so much in demand that in 1980 a second one was built and, for a time, both tanks were working 24-hours shifts. The tank was built on land earmarked for the future wing of a large building and I had to promise that I would not oppose its removal after a period of five years.

  Last year, Edinburgh University made a successful bid for £7 million to the Joint Infrastructure Fund which distributes money from the Wellcome Foundation and the Office of Science and Technology for major university building projects for specific research topics. Selection is based on advice form the EPSRC referees, who could not be expected to know about EPSRC grants for wave energy.

  When I heard of the possibility of the bid I told the University authorities I would of course honour the promise I made in 1977 but that I would like money for tank relocation to be included in the application. This would have amounted to about 1 per cent of the total building cost. I was given a written assurance that this would be done. I have just learned that this clause was not included and that the site on which our tank stands will have to be vacated in June. A brand new replacement of the tank would cost about three-quarters of a million pounds and the loss of the tank means that I will seriously compromise a research project for EPSRC valued at nearly a quarter of a million. Neither the OST, nor EPSRC and certainly not Wellcome, can be blamed for an unfortunate change of policy in a university which is the result of the financial pressure now being suffered by all universities. However, perhaps any similar bids in future could carry a specific question about unintended collateral damage arising from what should have been a very happy event.

  The JIF bid could eventually perhaps have a fortunate outcome. We have been working on designs for a new tank which would be able to generate both waves and currents independently round the full 360 degrees, with continuous sweeps through all the variables of spectrum, direction and current-velocity. Its design has been influenced by the requirements of tidal-stream research but there will be many other applications. It is known from ship losses off Cape Agulhas and the Pentland Firth that some very interesting and dangerous things occur when currents move directly into waves. The tank could also be used for work on low-head hydro, tidal surges, flood defences and rising sea levels. A pre-print of a paper to given at the Marec 2001 conference describing the design of the new tank is attached.


  Proposal for a large, vertical-axis tidal-stream generator with ring-cam hydraulics. Pre-print of a paper to the Marec 2001 conference, Newcastle March 2001.

  Evidence to the Energy Committee, 11 March 1992 volume III pp62-77. HMSO.

  Changing the 1981 Spine-based ducks. IEE Renewable Energy Clean Power 2000.

  Conference 17-19 November 1993. IEE London. pp121-130

  (Discusses improvements suggested by the release of the Thorpe analysis.)

  Memorandum to the Small Hydro Strategy Meeting, 4 September 1996.

  (Discusses the European dimension and the Cape Wrath spur.)

  Political Decisions about Wave Energy. Note written at the request of DTI following the appointment of John Battle as Minister for Energy.

  (Discusses UK problems and includes a discussion on the hazards of the marine environment and argues the case that the land can be even worse.)

  Edinburgh Input to Ove Arup study on wave energy for DTI. 21 August 2000.

  (Discusses further research needs.)

  Proposals for a combined wave and current tank with independent 360º capability. Pre-print of a paper to the Marec 2001 conference, Newcastle March 2001.

  VHS video tape of wave energy experiments on models in test tanks.

9 February 2001

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