As I write on a very sunny day at the end of summer, the UK is currently consuming 34.4GW of electrical power. The major players in this generation game are
- Combined Cycle Gas Turbines (10.71 GW)
- Solar Power (8.55GW)
- Nuclear Power (5.22 GW)
- Wind (3.81 GW) [1].
This blend of daily energy is unique and driven by the regional availablity of renewable energy sources and emergent demand. Other technologies like CCGTs are on hand to rebalance the network in the event of calm winds and cloudy days. While nuclear power sits behind the scenes providing a steady yet relaible baseload. Interestingly, these rotating machines also provide stability to our grid, but thats a story for another day [2].
Increasingly the production of renewable energy is at the forefront of UK’s Net Zero Carbon objectives, with significant funding and innovation drives providing additonal momemetum to support creative ideas. These innovation drive are largely due to the UK’ legal obligation to achieve Net Zero by 2050 [3].
In contrast to the variablity of wind and solar power, tidal energy represents untapped potential for the UK’s energy mix.
Its an exciting time for the tidal power industry with many companies benefiting from the green energy drive. For Tidal applications, the Offshore Renewable Engery Catapult [4] and theTidal Stream Industry Energiser [5] are supporting a range of projects to increase the technical readiness of front running design concepts.
Tidal Stream turbines have yet to converge on a specific design. This is in part due to the complex flow regimes associated with different locations and the unavoidable challenges of submersed operating environments. As well as broader considerations such as scalability, maintainablity and full life cycle cost.
Once these systems have a proven track record in the field and demonstrated they can operate sustainably as part of the broader marine infrastructure, the tides could change for the industry. Development is always challenging and uncharted wasters, riddled with high capital expendature and no fixed promises of future revenue. However, as with most technological breakthroughs, their impact is often underestimated…
Listed below are some of the leading companies in tidal stream development that think they could be provide on track for a feasible power take-off solution and they are not alone, having received funding from the ORE Catapult and TIGER to progress their designs.
HydroQuest [6] have approached the the problem with a modular vertical axis turbine and are aiming to scale up to a 2MW prototype. Such a design has an advantage of being less dependent on directional flows, allowing it to operate in more turblent conditions. The modular design also provides good opportunity for scalability, and the seabed base allows for efficient deployment while at sea.
Orbital Marine Power’s [7] 02 device claims to be the world’s most powerful tidal turbine and has been operational since July 2021 in Orkney, where it is connected to the UK electricity grid. It is a 74m long floating superstructure, supporting two 1 MW turbines on either side for a nameplate power output of 2MW. The design is more closely related to a conventional wind turbine, with specificly designed blades to manage the density of water, whilst be optimised for the operational operational flow characteristics.
It can generate enough clean, predictable electricity to meet the demand of around 2,000 UK homes and offset approximately 2,200 tonnes of CO2 production per year.
Its floating design minimises subsea structures and the associated environmental impact of mounting on the seabed. The structure is also accessible by boat allowing schedule maintenance activites to be conducted efficeintly within the need for heavy machinery.
Minesto’s Tidal Kite Dragon Class [8] is currently being redeveloped through the TIGER funding initiative. This noval approach to power extraction uses the principle of a kite, achored to the seabed to extract power from the onboard turbine. The wing uses the hydrodynamic lift force created by the underwater current to move the kite. With an onboard control system, the kite is autonomously steered in a predetermined figure-of-eight trajectory, pulling the turbine through the water at a water flow several times higher than the actual stream speed.
The turbine shaft turns the generator which outputs electricity to the grid via a power cable in the tether and a seabed umbilical to the shore.
Proteus [4] are continuing advancements of their AR Series Turbine through TIGER. This system has also taken inspiration from conventional turbine design utilising active pitch control and full nacelle yaw rotation to maximise energy extraction while adapting to changing flow patterns. Its been designed with reliablity in mind, due to its complex structure minimising lifiting activities at sea will be an important consideration for a design of this scale.
Proteus have great ambitions for thier installed capacity over the next ten years and already have systems operating in Japan, France and Scotland.
Looking at these creative approaches to Tidal Energy is great introduction to the field and shows the range of approaches that are currently being investigated.
Our Tide is aiming to support the development of the industry by facilitating the testing and deployment of new small-scale designs by utilising the periodically submerged infrastructure of the Clevedon Pier.
The pier is a unique facility due its accessibility at low tide. Allowing engineers and designers to install and monitor systems within their operating environment, with significantly less complexity.
Our Tide hopes that this real-world testing platform will help support the development of tidal stream expertise within the UK and engage the next generation of engineers to peruse creative approaches to the UK Net Zero targets while testing them in UK waters.
Bibliography
[1] M. Stolworthy, “Gridwatch,” [Online]. Available: https://gridwatch.co.uk/. [Accessed 05 09 2023].
[2] National Grid ESO, “Stability Pathfinder,” [Online]. Available: https://www.nationalgrideso.com/industry-information/balancing-services/pathfinders/noa-stability-pathfinder. [Accessed 2023].
[3] UK Parliament , “UK Parliament – House of Lords Library,” [Online]. Available: https://lordslibrary.parliament.uk/net-zero-transformation-industry-and-regulators-committee-report/#:~:text=In%20June%202019%2C%20the%20UK,also%20set%20net%20zero%20targets.. [Accessed 2023].
[4] Offshore Renewable Energy Catapult, [Online]. Available: https://ore.catapult.org.uk/. [Accessed 2023].
[5] European Union Regional Development Fund, “Tidal Stream Industry Energiser,” [Online]. Available: https://interregtiger.com/. [Accessed 2023].
[6] HydroQuest, [Online]. Available: https://www.hydroquest.fr/en/. [Accessed 2023].
[7] Orbital Marine, “Orbital Marine – Project Sites,” [Online]. Available: https://www.orbitalmarine.com/projectsites/. [Accessed 2023].
[8] Minesto, “Our Technology,” [Online]. Available: https://minesto.com/our-technology/. [Accessed 2023].
[9] “OffshoreWind,” 2013. [Online]. Available: https://www.offshorewind.biz/2014/02/26/video-ar1500-tidal-power-turbine-system/. [Accessed 2023].