The old adage expresses the inevitability of the tides – huge volumes of water moving relentlessly around our shores, like clockwork, controlled by the phases of the moon. It is only recently that humans have started to develop methods of extracting energy from this predictable source of renewable energy for our daily lives. Fossil fuel prices and security, combined with climate change predictions are driving the huge development of wind and solar energy, but the wind doesn’t always blow and “Sunshine on Leith” can be missing for long periods of the year. Tidal stream energy is a completely dependable and is quite invisible too.
Modern wind energy started with community groups in Denmark, in response to the 1970s oil crisis, and has developed into a multi-billion pounds international industry. The average height of wind turbines is now over 150m and the power generated is greater than 5MW per turbine. The huge wind blades (largest over 100m in length) are built from lightweight glass and carbon fibre-reinforced polymers for strength and durability. The Scottish Government “ScotWind” auction in January of this year has licenced 25GW (or 2,500 huge 10MW wind turbines) for offshore installation (either in the seabed or on floating platforms) over the next decades.
The development of marine renewable energy (wave, tidal stream and offshore wind energy) has been a major research activity of the School of Engineering at The University of Edinburgh since the 1970s, led originally by Professor Stephen Salter, the inventor of the most efficient wave energy machine at the time, called “Salter’s Duck”. The last 40+ years has seen huge advances in wind energy production in Scotland and the UK, with Scotland producing greater than 97% of its electricity from renewable sources in 2020, mainly from wind energy. Despite several false starts, development in marine renewables has continued, with the support of Government bodies such as Wave Energy Scotland and EPSRC, Innovate UK and European Union research and development programmes. A recent spin off company from the School of Engineering in marine renewable energy is the wave energy company Mocean Energy, who have developed the Blue-X wave energy device
To come back to the harnessing of tidal stream energy, we have an enormous, predictable source of unharnessed energy here in Europe and particularly around British waters, with large amounts of tidal energy resource located in the north of Scotland, on the Welsh coast, and in the Channel between England and France. Estimates point to 10 GW of predictable, high value tidal stream potential in European waters, with up to 100 GW of capacity globally [1].
According to the ETIP Ocean (2019) report [2], “Europe has a rich source of clean, predictable ocean energy, which today remains largely untapped. The ocean energy industry estimates that 100GW of wave and tidal energy capacity can be deployed in Europe by 2050, meeting 10% of Europe’s current electricity needs. Ocean energy produces electricity at different times from wind and solar. It is an essential solution to help a variable wind and solar production match with a variable power demand every hour of the day. This will become increasingly valuable as Europe reaches 80%-100% renewable electricity. Ocean energy is a new industry, that can deliver 400,000 EU jobs by 2050, billions of euros in exports, and industrial activity – specifically in coastal regions, where this is most needed.”
The first tidal farm to be linked to the electricity grid was the 6MW Meygen project in the Pentland Firth, Scotland where 4 seabed-mounted turbines were installed in 2018.
Scottish company, Orbital Marine Power have developed and are trialling a pre-commercial floating 2MW tidal stream turbine at the European Marine Energy Centre (EMEC) in Orkney. The following video shows the O2 turbine generating energy in Orkney and please note that it is anchored, even though it appears to be moving !
Tidal flows as shown in the video can clearly contain enormous amounts of energy. The UK Government has recognised the potential of marine energy by ringfencing £20M of support for the industry through its latest Contracts For Difference programme [3]. The cost of tidal stream energy will have to reduce by almost half from the current estimates of £150-200/MW.hours, in order to be competitive as a source of predictable, dispatchable energy.
So what is the role of university researchers in helping companies to reduce the current cost and make this tidal stream energy available to power our homes, schools and businesses ?
The main supports we can provide are by educating well-trained engineers, scientists and business graduates; and by providing advanced testing and certification facilities for the industry to improve and perfect its device designs. The University of Edinburgh established the world-leading Flowave circular tank for wave and tidal testing of marine renewable energy devices in 2013, with EPSRC funding. Flowave has become an essential part of companies’ path to development, by de-risking the device designs at an early stage. Have a look at the following video of testing of 3 scale model tidal turbines in Flowave:
https://media.ed.ac.uk/media/Three+tidal+turbines+under+test+in+FloWave/1_5y82slz3
The tidal stream energy industry is just about to enter its commercialisation phase, and many tidal farms will be built around our coasts in the next few years. The design of the fibre-reinforced composite blades that are used to generate the power is not straightforward, however, and can’t be de-risked by learning from their much longer wind turbine blade cousins. Tidal blades must last for 20-25 years in very aggressive conditions and must reliably produce power for their lifetime.
To help the industry in testing and certifying their turbine blades, the University of Edinburgh has developed the new FastBlade test facility, which will be based in Rosyth Dockyard in Fife. Funded initially by a £1.8M EPSRC grant, and with added £2.8M funding from the University, FastBlade is the first dedicated fatigue testing facility for tidal turbine blades in the world. The facility was developed in partnership with Babcock International Group and can test and certify full-scale tidal blades, as well as being available to researchers to investigate new manufacturing techniques and materials. FastBlade uses super-efficient Digital Displacement Hydraulics® (developed by a spinout company of the University, now part of the multinational Danfoss group) to do regenerative hydraulic pumping. This enables full lifetime accelerated fatigue loading of tidal turbine blades to be carried out in a matter of months, thereby verifying the design methodologies and greatly reducing the risk of blade failures during the lifetime of the turbines.
FastBlade will be officially opened on Friday May 13th and will add another chapter to our University’s research and innovation in the field of renewable energy.
References:
- https://ore.catapult.org.uk/?orecatapultreports=tidal-stream-and-wave-energy-cost-reduction-and-industrial-benefit
- https://www.oceanenergy-europe.eu/wp-content/uploads/2019/04/ETIP-Ocean-Integrated-Strategy-2019-LR.pdf
- https://www.gov.uk/government/news/uk-government-announces-biggest-investment-into-britains-tidal-power
