Ocean Wave Energy a real option for Ireland
|A thirteen mile strech of ocean between Belmullet and Valentia on the west coast of Ireland is capable of providing up to ten per cent of the energy needs for the entire country. This can be done without atmospheric pollution and the resource is sustainable indefinitely. Vested interest and lack of Government commitment holds up the research.|
|By Brian Ó Gallachóir|
Atmospheric pollution from the burning of fossil fuels, depletion of the Earth's natural resources and the fear of radioactive emissions from nuclear plants make the concept of renewable energy resources particularly attractive today. Ocean waves are one of the world's most abundant sources of renewable energy, generated as a result of wind blowing over the ocean surface. Since winds themselves originate due to the uneven heating of the atmosphere by the sun, wave energy may be seen as a byproduct of solar energy.
The concept of harnessing wave energy is not new and there have been over a thousand ideas patented in the last two centuries. Very few of these ideas were constructed and tested at sea and until the 1970s the powering of navigation aids represented the only commercial exploitation of wave power. Early this century, several navigation buoys were equipped with a vertical tail tube open at the bottom to allow the waves to oscillate the column of water within. The resulting piston like motion of the water was used to force air through a whistle and the initial oscillating water column wave power devices were born. 1 In the 1960s the whistle was replaced with a turbine generator and to date wave powered navigation buoys which operated in the seas around Ireland represent our only commercial development of this vast resource.
It is interesting to examine the criteria used when renewable energies are considered from an economic perspective in comparison to criteria used for other sources of energy. In the case of fossil fuels, it is accurate to calculate the sale price of 1 kilo Watt hour of electricity and deduce from this that if the price is lower than for wave energy, then it is the cheaper option? How could it be without taking into account the hidden costs associated with fossil fuels such as the amount of money now devoted to researching the extent and possible ways of alleviating the damage caused to the environment? Neglected also are the research costs spent on developing the fossil fuels to their present levels of efficiency which far exceed those of renewable energies.
This is an extremely important factor in the debate surrounding the funding of research into harnessing nuclear fusion as an energy source. Most of the expenditures for energy research and development in the last 50 years have been spent on nuclear energy. This is despite the fact that in most countries, this alternative has been rejected by the general public due to the dangers associated with nuclear reactors as a result of accidents at Chernobyl, Three Mile Island and Windscale (renamed Sallafield). Are the costs of safety (if this is possible) decommissioning a nuclear plant included in the price attached to 1 kilo Watt hour of electricity?
Regarding nuclear fusion specifically, annual budgets globally are of the order of $1 billion despite the fact that the proposed date for commercial viability (which again will not take into account the research costs) is continually being projected further and further into the future.
The EC fusion budget grew steadily between 1977-1988, levelling off then at an annual amount of 400-500 million ECU with major increases to 700-800 million ECU being projected for the late 1990s.2 Wave energy by comparison has been researched by a small group of dedicated scientists and engineers since 1974 on a mere pittance. Nevertheless, one device has been developed to the commercial stage already with several others not far behind. The first EC funding was granted in 1993 amounting to 1.2 million ECU for an 18 month study. The total budget for the two year period 1994-1995 based on a 50% EC funding contribution is 5-6 million ECU.3
Wave Power Resource
It has been estimated that the total wave power resource in all the oceans at any one time is about 1 TW (ITW=Terra Watt= 109 kW) which corresponds directly to the present amount of electricity produced in the world.4
Due to Ireland's geographical location, on the downwind side of the Atlantic Ocean in the region of prevailing south-westerly winds, her coastline is exposed to one of the most vigorous wave climates in the world. Anyone who has walked along the western coastline will be well aware of this. This climate gives the Irish west coast, from Malin Head to Cape Clear, among the highest coastal wave power levels in the world.
While some instrumental recordings of waves have been made,5 the power levels have been calculated largely using wind speed information. Professor Denis Mollison was commissioned as early as 1982 to assess Ireland's wave power resource by the then National Board of Science and Technology (NBST). He used estimates that were based on wind speed information from the UK Meteorological Office's 10-layer atmospheric model. Mollison found that the overall resource around the west and south coasts of Ireland is about 25 GW (1GW - 1 Gita Watt - 106 kW) mean.6 This figure corresponds to an annual gross amount of energy of 219 Terra Watt hours which when compared to ESB figures for 1992 7 represents nearly 15 times the amount of electricity produced in that year. It will not be possible to harness all of this resource but simple estimates for a line of wave energy devices indicate that, when losses are included, a 13 mile stretch between Belmullet and Valentia could provide 10% of the ESB's generating capacity for 1992.
The ocean waves are a source of clean, natural and renewable energy. The harnessing of wave power does not cause large carbon dioxide emissions, which would allow it to play an important role in counteracting the threats of global warming. There are no dangerous and harmful byproducts which are comparable to the radioactive waste produced at nuclear power plants. As with any interactions between humans and the rest of the natural world there is however, an impact on the environment some aspect of which being negative though not all (offshore devices, for example, could help reduce coastal erosion).
The impact of wave energy converters (WECs) on ecosystems will be minimal but site specific problems may arise. Water circulation within the near shore region may be altered by large numbers of WECs mounted on the sea-bed, which may affect migratory species such as salmon and also the growth of algal species such as Laminaria. 8
The construction of large offshore devices could have serious consequences for wave patterns and sedimentation rates. In areas in need of coastal protection this may be of benefit. The impact on drift patterns and secondary effects on the local ecology requires further study.
The visual impact of the WECs will be minimal and of more concern is the impact of transmission systems as most areas suitable for the harnessing of wave energy will have high scenic beauty. Onshore devices will emit some noise but it is expected to have a relatively low intensity. Areas in front of WECs will exhibit short, confused seas in storm conditions and the leeward side could provide shelter for small vessels. To avoid being considered a hazard to shipping adequate navigational guides must be provided. Most areas with suitable wave climates have a low density of marine traffic but fishing activities are common in these areas and care to avoid spawning or feeding grounds is essential.
Research in Ireland
Wave energy research in Ireland was initiated at Queen's University, Belfast (QUB) in 1975 following the invention by Professor Alan Wells of a self-rectifying turbine. This Well's turbine always rotates in the same direction irrespective of the direction of input flow and provides an ideal method of electricity generation from a variable oscillatory flow, upon which principle the oscillating water column (OWC) wave energy device9 is based.
The OWC consists of a large chamber enclosing a column of water which is forced to oscillate by wave action driving the air above through a turbine to generate electricity. The heart of the QUB device was an air turbine with special qualities: its rotor is driven in the same direction whether air is forced through it axially from one side or the other.
1979 marked the beginning of wave energy research in University College, Cork (UCC), the principle research centre in the South. A continuous programme of research has been carried out supported by national and EU funding. Two other Irish institutions have been involved in specific aspects of developments. University College Galway was briefly involved in a project of the International Energy Agency analysing data from a Japanese devise tested at sea, the Kaimei.
University of Limerick has considerable experience in turbine development and has worked extensively with Portuguese partners, most recently in a study on turbines need to equip a 0.5 MW wave power plant to be built in the Azores. It must be stressed that both the paucity of funding and the absence of a structured national programme have been extremely detrimental to the development of wave energy devices.
The research team at QUB were one of the groups to benefit from the official interest in wave energy which began to develop in the UK in the wake of the first OPEC oil crisis in 1974. The team embarked on a programme to investigate the design parameters of an OWC device, taking into account hydrodynamic and engineering considerations. They submitted two detailed designs for a 2GW offshore wave power station to the UK Department of Energy, the last in 1982 when the UK government made a controversial decision to cease funding the programme. After this attention was turned towards smaller scale commercial applications of wave power technology. Working in close co-operation with The Commissioners of Irish Lights, Trinity House and Munster Simms Engineering Ltd., the team tested a 100 W Wells turbine generator installed in an Irish Lights wave powered navigation buoy.10
In 1985 the team commenced work on designing a medium sized wave power unit suitable for island communities. A small gully close to the village of Portnahaven on the Isle of Islay off the west coast of Scotland was selected for a prototype demonstration.
Construction commenced on the site in the Summer of 1987 and was completed in November 1988. The turbine was installed in late 1990 with a 75 kW generator and was connected to the Islay grid in 1991.
The team were recently working in conjunction with HMRC on the final design for a 500 kW pilot plant at another location on Islay but the British government decision in July 1994 to severely cut funding for wave energy research has caused a major setback in this project.
All three areas necessary for the development of a wave energy have been simultaneously explored in UCC, namely mathematical modelling of wave energy converters (Department of Mathematical Physics), laboratory research and field trials (Hydraulics and Maritime Research Centre, HMRC). The mathematical models have used the hydrodynamic theory of water waves as a starting point to explore how waves interact with the various devices and to then develop computer models which optimise efficiency. Taking the results from these computations into account at the tank testing stage and development at sea stage can greatly reduce time spent and thus costs.
The 15 m long random wave tank at the HMRC have been used for optimisation testing of various chamber configurations for OWC devices and for developing a novel self rectifying turbine in which the rotor is constructed in radial flow configuration in an attempt to overcome some problems associated with the Well's Turbine.
Field trials were carried out at Bull Rock, an island off the Beara Peninsula which holds a lighthouse. In 1982, the Commissioner of Irish Lights decided to cap a blow hole on the Rock due to the corrosive sea-water spray. As blow holes are naturally formed oscillating water columns, HMRC inserted steel pipes into the concrete slab to monitor the air flow. Another blow hole was developed in 1984 and following strengthening work in 1985 measurements were made and this continued until November 1986.
A new wave test basin 25 m long by 18 m wide and up 2.5 m deep has been constructed which is fitted with 40 computer controlled wave generators to simulate real sea conditions at model scale. This allows for the testing of wave energy devices to be carried out.
At present the research teams are participating in a number of EU sponsored projects which are funded under the JOULE renewable energy programme and final design for two pilot plants will be undertaken by the HMRC team with partners in Portugal and Belfast. UCC also plays a leading role in a project on the long term strategy for the development of off-shore wave energy devices.
|We hear and read mixed messages regarding renewable energy from succesive governments.||
Possibilities for Future Development
At its present stage of development wave power is an ideal energy source for small scale utilisation such as island communities. Therefore it has important implications for Ireland particularly regarding the saving of fossil fuels currently being used by such communities. Large scale harnessing of wave energy cannot be a reality for at least ten years and this will only be possible if sufficiently large resources are made available now to a strategically planned programme.
This resource is situated along an area of Ireland which has been scourged by unemployment. There is a marked absence of structural support for a long term development strategy defined by and based on the needs of the local people. This coupled with emigration, the industrialisation of the fisheries and associated problems have resulted in parts of the west fast becoming ghost towns. The harnessing of wave energy could be very useful as part of a much needed long term plan for the area.
On-shore and near-shore OWC devices are at an advanced stage of prototype development with device teams in Japan, Portugal and the UK. Ireland is playing her part in these developments, funded through the EU renewable energy programme. Specific interest in the European Parliament in 1990 led to the instigation of a review of research into wave energy conversion with a view to incorporating this into the JOULE programme. A position paper was prepared for a seminar in Brussels in April 1991 and Preliminary Research Actions were carried out in order to evaluate the status of wave energy research in general, and make proposals for research activities for a European wave energy research programme.
Initial findings were announced at a workshop held in Cork in October, 1992 and final results presented at the 1993 European Wave Energy Symposium in Edinburgh. On the basis of this work the inclusion of a wave energy research and development in the JOULE II programme was announced and projects have been supported for the 1994-1995 period. A further call for proposals was made in December 1994 for the follow up to JOULE II which will run until 1998.
But where is the Irish government support? Will matching funding for specific projects be invested?
It is part of the ESB's Environmental Policy to "utilise renewable energy sources, where economic. We will also encourage the development of new renewable resources" 11 A wonderful sentiment which fits perfectly to wave energy but one could well ask when this is to be put into practice.
We hear and read mixed messages regarding renewable energy from successive governments. The first commercial wind farm in Ireland was officially opened in November 1992 which was a great boost to renewable energy supporters. In September 1993 however, at Rhode Milled Peat Power Station, Minister Brian Cowen highlighted how this wind farm with its 6.5 MW capacity was only a token gesture. He undertook to give his "fullest consideration" to the feasibility study submitted by Bord na Móna on the possible construction of a new 120 MW peat fired station, which would be located somewhere in the midlands.12 Then came the initiative announced by Minister Noel Treacy in October 1993 to ensure that additional electricity supplies of up to 75 MW are provided from renewable energy sources before 1997.13 In terms of long-term investment of indigenous resources which would you support, the further destruction of the fast depleting boglands or the harnessing of natural renewable resources such as the waves, the wind and the sun?
Brian Ó Gallachóir is currently researching wave energy at the Department of Mathematical Physics, University College Cork.
1 Whittaker, T.J.T. 1987 Recent Developments inWave Energy Systems. Institution of Electrical Engineers 5th International Conference on Energy Options, Reading, April 1987.
2 Woolridge, Jim 1993 Focus on Fusion. Earthwatch.
3 European Wave Energy Research Network 1993 Wavelength Newsletter Issue No.2.
4 Lewis, A.W. 1993 Wave Energy: Current Research Activities and Recommendations for European Research Programme. Final Report to D.G.XII/E.
5 Lewis, A.W. 1986 Wave Energy Research in Ireland. Symposium on Utilisation of Ocean Waves, La Jolla, California.
6 Mollison, D. 1982 Ireland's Wave Power Resource. NBST.
7 ESB, 1993, Annual Report for the year ended 31 December 1992
8 Lewis, A.W. 1984 Wave Energy. An Evaluation for the Commission of the European Communities. Published by Graham and Trotman Ltd.
9 Long A.E. & Whittaker, T.J.T. 1986 Wavepower - A Challenge to Engineers. Vernon Harcourt Lecture presented at Gt. George St.
10 Whittaker, T.J.T. 1987 Recent Developments in Wave Energy systems Institution of Electrical Engineers 5th International Conference on Energy Options, Reading, April 1987
11 ESB 1993 Annual Report for the year ended 31 December 1992
12 Collier Eleanor 1993 Minister Committed to Continued Use of Peat. Tullamore Tribune, 25.9.1993
13 Dept. of the Environment 1994 Environment Bulletin Issue No. 21.