Renew On Line (UK) 56

Extracts from NATTA's journal
Renew, issue 156 July-Aug 2005

3. Wave and tidal power

SeaGen goes ahead

As noted in Renew 155, Marine Current Turbines Ltd has won an award of a DTI Grant of £3.85m towards its £8 million ‘SeaGen’ 1MW tidal energy turbine project.

They aim to install the SeaGen turbine in UK waters and connected to the National Grid during 2006. It will be three times as powerful as Marine Current Turbines’ existing ‘Seaflow’ turbine, which was the world’s first offshore tidal turbine. The 300KW turbine was installed off Lynmouth, Devon in May 2003.

Martin Wright, Managing Director of Marine Current Turbines said: “We are delighted that the DTI is backing MCT’s ‘SeaGen’ Project. It’s a most critical step to achieving a practical and cost-effective commercial technology, and the DTI grant is a vital part of that process. Moreover, it was made after a very thorough assessment of our technology and its commercial prospects, and we are delighted to have won it. Above all the grant, together with the support of our investors provides a sound platform to take the technology forward and show that tidal energy has a real contribution to make to the UK’s energy mix. We believe we have made a major breakthrough in terms of extracting clean energy from the sea.”

MCT say  that its earlier ‘Seaflow’ turbine, installed off Lynmouth last year, is now successfully operating unattended and remotely controlled, and is performing better than the design expectation- the energy capture has been up to 25% better than expected. In addition it has also exceeded the originally planned project operating period and ‘will be run for at least another 12 months in its exposed location’.

Overall MCT say that the ‘Seaflow’ project, which was also supported by the DTI as well as by the EU, has been invaluable in proving the fundamentals of the technology, and significantly advancing the knowledge of all aspects of design and operations.

* The new ‘SeaGen’ turbine has twin rotors each driving a 500kW generator compared with ‘Seaflow’s’ single 300kW rotor. Tidal turbines work on the same principles as a windmill, with large underwater rotors, shaped like propellers, being driven by the huge mass of flowing water to be found at certain places in the sea.

MCT say that the fundamental advantages of this technique are:

• tidal currents are predictable far into the future: Tidal streams are driven by gravity, unlike wind, wave or solar energy which depend on the relative randomness of weather, making it possible to offer firm power which is inherently more valuable than randomly available power.

• high energy intensity: The high energy intensity of this resource means that a 1MW tidal turbine can access five to ten times as much energy per square meter of rotor than a 1MW wind turbine, resulting in a smaller and potentially lower cost machines.

• minimal environmental impact: tidal turbines are visible enough to be avoided by mariners but they have a low visual impact on the seascape, they produce no pollution or noise and their slow moving rotors which turn at less than one revolution in four seconds (15 rpm) are considered unlikely to harm marine life.

• High energy return on energy invested: tidal turbines should offer faster energy payback than most other renewables.

• Conditions under the sea in a storm are relatively benign (as is well known to submariners) so the technology is relatively immune from damage due to extreme storms and waves unlike offshore wind and wave systems- and this should reduce costs.

Lunar Power

£2.25 million more will go to Lunar Energy of East Yorkshire to develop its two way novel ducted  fan  tidal current device.  A 1MW prototype will be installed at the European Marine Energy Centre on Orkney early in 2006. If testing is successful, the company expects this to lead to larger pre-commercial devices. Energy Minister Mike O’Brien said:  “It is now fair to say that the UK is not only the world leader in this field, but also the most attractive place to locate and develop these technologies. Our support for companies such as Lunar Energy is designed to ensure that we maintain this position.” 

The UK wave energy company Ocean Power Deliver has won a contract from a Portuguese consortium for an initial £5.5m  2.25MW project using its Pelamis articulated sea-snake device.

Stingray on hold...

Lunar power and the Seaflow ‘Seagen’ tidal current projects may be doing well (see earlier) but as noted in Renew 153, the Stingray  tidal project has been put on hold. The developer, the Engineering Business, said that “this difficult decision is not a result of technical issues but is down to simple economics”.  They added: “For a small private company to stay in business the golden rule is to generate cash. There is funding available for future development but not on the scale or basis that will allow EB to rapidly or profitably make Stingray a commercial reality. Despite the significant support of the DTI, NaREC and Shetland, given the timescales involved and investment required, EB cannot continue to sustain this project on a non-profit basis. Because of this we have taken the hard decision to put Stingray on hold. Having invested significant EB funds and 4 years of our lives in demonstrating the technical viability of the system, we share the disappointment of other stakeholders. However, we have to apply our skills to projects that will ensure the long term viability of EB.”

 ... but EMREC expands

The Scottish Executive has awarded over £1m towards the establishment of a wave and tidal test centre at the European Marine Energy Centre in Orkney, as part of a package worth £6m to extend the pioneering work already being undertaken at EMEC. The wave test facility at EMEC became operational in October 2003. The first user was Ocean Power Delivery, who began testing their Pelamis device in late summer 2004. A second developer is now beginning trials and other developers may begin testing later this year or in 2006.

So far, Scottish Enterprise has approved a contribution of £600,000, DTI has agreed to contribute £700,000 from its new marine energy fund, Orkney Islands Council has agreed a contribution of £500,000, and Highlands and Islands Enterprise has agreed to contribute a maximum of £1.08 million. The Carbon Trust will contribute £900,000 towards the revenue costs of the new facility.

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...but what about grid costs in Scotland?

Scotland has a lot of wave, tidal and wind resouces-but they are in remote locations.   Ofgem, the energy regulator, has decided that generators in remoter parts of the UK must pay higher transmission charges than those close to markets. This drew a warning from former Energy Minister Brian Wilson, still a Scottish MP, who said that it was therefore unlikely that projects would go ahead in peripheral and island areas where resources were at their best. He told the Scottish  Herald  “The Ofgem decision on locational charging is just one part of the jigsaw, but it sends a clear signal. Their view is that generation should take place close to markets, preferably south of The Wash, and they have no intention of authorising the infrastructure investment required. I said two years ago that there were huge difficulties to be overcome if all the talk about renewables was going to be turned into action and jobs.  The reality is that communities are divided, environmental bodies are more hostile to windfarms than to global warming and the political signals are very mixed. In these circumstances, it was very easy for Ofgem to maintain its ideological position.”

However it may not be quite as bad as Wilson fears.  Mike O’Brien, then still Energy Minister, outlined plans to limit grid transmission charges to renewable generators on the Scottish Islands, and potentially in the far North of the Scottish mainland, so as to protect local consumers from high electricity prices.  And he said, in general, Scotlands inclusion in the new BETTA trading arrangement should reduce prices. Under the Energy Act 2004 the government can adjust transmission charges for renewable generators in a specified area if the charges would otherwise deter renewable development in that area, and the Common Tariff Obligation (CTO) will ensure that suppliers in the North of Scotland cannot charge domestic customers in the area different prices simply on the basis of their location.

Wave and tidal 'costly'

When the House of Lords discussed wave and tidal power on 24th March, DTI Minister Lord Sainsbury commented that ‘although wave energy is not currently economic, we believe that in the longer term it has the potential for significant cost reduction. We are therefore providing support to help realise that potential. In August last year, we announced a £50m marine renewables deployment fund that will provide continued support to wave and tidal stream power technologies. That builds on the £20m of support for research and development provided to the sector since 1999 and the £1.2m provided towards the European Marine Energy Centre in Orkney. Additionally, the Carbon Trust has invested more than £6m in marine energy projects, and the Engineering and Physical Sciences Research Council has a £2.6m SUPERGEN marine programme.’

However Baroness Miller argued that wave energy was not economic yet ‘because the economies of scale needed in any energy production simply have not been reached’, in which case, given that the energy was free, predictable and involved no waste legacy, shouldn’t more effort be made and any regulatory blockages be removed?

Lord Sainsbury replied that he was ‘not certain that in this case there is an issue of economies of scale. The position is that the cost of wave and tidal energy is still orders of magnitude higher than any other at the moment. At about 15 to 20p/kWh  it is still very expensive. It is also not true to say that there is no question of legacy. There is a real question of how to decommission barrage lagoons and what impact that has on the environment. I am not aware that the regulatory system is particularly complicated. Clearly, environmental impact should be applied to this in the same way as it is to any other project in the energy field.’

The Bishop of Liverpool then intervened ‘If all reasonable exploitable estuaries were utilised, the annual generation of electricity from tidal power plants could achieve a potential of 50 TWh, equivalent to about 15% according to the DTI survey, of current UK electricity consumption’.

Lord Sainsbury agreed with that estimate but repeated ‘at the moment the issue is one of cost. The cost is something like five times higher. As is clear to everyone here, in energy policy you have to satisfy questions of cost, energy security and the environment and you have to get the right mix of energy sources to achieve those three objectives.’   He added ‘We believe that the spread between different technologies should be decided by the marketplace and not by attempts to make Government predictions’ adding that the Severn barrage project ‘would cost between £10 bn and £14 bn and also raises very strong environmental issues’.

Lord Livsey pointed to the research that has been done in Swansea Bay on tidal lagoons and suggested that in view of the potential of tidal power ‘the present contribution of £50 million to the industry is inadequate, particularly when compared with that given to wind power?’  

Lord Sainsbury replied:‘the Swansea Bay proposal uses older technology. It’s technically feasible. There’s considerable disagreement about the cost of the construction and the amount of energy that it will produce. If the figures that have been produced by the promoters of the scheme are correct, there should be no problem with obtaining commercial funding for it from the market. As no innovation is involved, it is not appropriate as an R&D project.’