This project aims to demonstrate at model-scale a novel technology to reduce unsteady-loading for tidal turbines, improving resilience and reliability, and decreasing the levelised cost of energy. Tidal energy is a promising renewable energy source that can contribute to providing energy security to the UK. The first and second array of tidal turbines has now been deployed in Scotland, confirming the UK as a world leader in this emerging energy sector. One of the main technical challenges of harvesting energy from tidal currents is the large load fluctuations experienced by the blades. These can result in fatigue failures of the blades and in power fluctuations at the generator that must be smoothed before power can be provided to the grid. The aim of this project is to develop a technology that cancels the unsteady loading at its source, while adding minimal complexity to the turbine to ensure high resilience and reliability of the overall system. The technology currently adopted to mitigate load fluctuations in air, such as that one employed by wind turbines and aerial vehicles, is not directly transferable to tidal turbines because of the harsh marine environment and the high hydrodynamic loads. For example, complex systems requiring hinges with bearings would be subjected to fouling and would reduce the blade reliability. To address this issue, we would consider introducing local flexibility that does not affect the key structural elements of the blade, and whose displacement can mitigate load fluctuations. The lowest loaded part of the blade is the trailing edge, and this is also where the smallest shape morphing can lead to the largest changes in the overall load. We could manufacture a blade made of the same material as a conventional rigid blade (fibreglass) but with a structural design that allows the trailing edge to bend to react to flow changes. To ensure high reliability of the system, we could exploit passive deformation without sensors and actuators. The small inertia of the part of the blade that bends would enable a prompt reaction to flow fluctuations. Our preliminary studies showed that a blade with a flexible trailing edge can theoretically mitigate more than 90% of the load fluctuations without affecting the mean power output. This project aims to verify these initial results by testing model-scale prototypes. We aim to design and manufacture two sets of 0.6 m and 1.2 m span blades to undertake fluid dynamics tests on a model-scale turbine and fatigue tests, respectively. These tests will demonstrate the efficacy, robustness, resiliency and reliability of morphing blades. The project includes key tidal and wind energy technology companies: SIMEC Atlantis Energy, Orbital Marine Power, Nautricity, Nova Innovation, Schottel Hydro, ACT Blades and Wood Group. Together with these industrial partners we aim to investigate the applicability of morphing blades to different tidal technologies, from 70 kW to 2 MW, from 4 m to 20 m diameter, and both seabed mounted and floating turbines with single and multi rotors. If proven effective for tidal turbines, we would also explore with our wind energy partners (ACT Blades and Wood Group) whether this technology is suitable to complement or replace some of the existing unsteady load mitigation technology currently adopted by wind turbines. Morphing blades could contribute to reduce fatigue loads, to increase reliability and lifetime yield, and hence to reduce the levelised cost of energy. It is envisaged that this technology could be more suitable for offshore wind turbines than onshore wind turbines because of the higher relative importance of component reliability. Overall this project aims to investigate the suitability of morphing blades to mitigate unsteady loads on tidal turbines, aiming at decreasing costs of blades and increase the energy yields, and thus decrease the overall cost of tidal energy.

The production, storage, distribution and conversion of hydrogen is a rapidly emerging candidate to help decarbonise the economy. Here we focus on its role to support the integration of offshore renewable energy (ORE), a topic of increasing importance to the UK given the falling costs of offshore wind generation (with prices expected to drop to 25% of 2017 by 2023) and Government ambition. Indeed, the latest BEIS scenarios include more than 120 GW of offshore wind, and even up to 233GW in some scenarios. This brings with it significant challenges to the electricity infrastructure in terms of our ability to on-shore and integrate these variable energy flows, across a wide range of timeframes. Current ORE plants composed of fixed offshore wind structures are sited relatively close to land in shallow water and use systems of offshore cables and substations to transform the electricity produced, transmit it to the shore and connect to the grid. However, in order to exploit the full renewable energy potential and requirements for the 2050 net zero target, offshore wind farms will need to be sited further offshore and in deeper waters. This brings possibilities into consideration in which transporting the energy to shore via an alternative vector such as hydrogen could become the most attractive route. Hence we consider both on-shore and off-shore hydrogen generation. Not only can hydrogen be an effective means to integrate offshore wind, but it is also increasingly emerging as an attractive low carbon energy carrier to support the de-carbonisation of hard to address sectors such as industrial heat, chemicals, trucks, heavy duty vehicles, shipping, and trains. This is increasingly recognised globally, with significant national commitments to hydrogen in France, China, Canada, Japan, South Korea, Germany, Portugal, Australia and Spain in the last three years alone, along with the recent launch of a European hydrogen strategy, and the inclusion of hydrogen at scale in the November 2020 UK Government Green plan. Most of the focus of these national strategies is on the production of 'green' hydrogen using electrolysis, driven by renewable electricity. However, there remains interest in some countries, the UK being one example, in 'blue' hydrogen, which is hydrogen made from fossil fuels coupled with carbon capture and storage and hence a low carbon rather than zero carbon hydrogen. Today, 96% of hydrogen globally is produced from unabated fossil fuels, with 6% of global natural gas, and 2% of coal, consumption going to hydrogen production, primarily for petrochemicals, contributing around 830 million tonnes of carbon dioxide emissions per year. Currently green hydrogen is the most expensive form of hydrogen, with around 60-80% of the cost coming from the cost of the electrical power input. A critical factor that influences this is the efficiency of the electrolyser itself, and in turn the generator used to convert the green hydrogen back into power when needed. In this work we focus on the concept of a reversible electrolyser, which is a single machine that can both produce power in fuel cell mode, and produce hydrogen in electrolyser mode. Electrolysers and fuel cells fall into one of two categories: low-temperature (70-120C) and high temperature (600-850C). While low temperature electrolyser and fuel cell systems are already commercially available, their relatively low combined round-trip efficiency (around 40%) means that the reversible solid oxide cell (rSOC), which can operate at high temperatures (600-900C) is of growing interest. It can achieve an electrolyser efficiency of up to 95%, power generation efficiency of up to 65%, and hence a round-trip efficiency of around 60% at ambient pressure using products now approaching commercial availability. This project considers the development and application of this new technology to the case of ORE integration using hydrogen.