presented the processes required for the production of thick-section composite parts using cost-effective liquid moulding processes, such as resin transfer moulding (RTM) and vacuum assisted resin transfer/infusion moulding (VARTM). Previously, there has been a limited amount of publications on the manufacture of thick section composite structures. Therefore, a solution that presents a robust connection that can be installed within the main manufacturing stages of the blade is required. However, issues arise with bonding to the composite materials and with dislodgement during installation. Currently, there are a number of solutions available, which are installed after the blade is cured. This results in the need for a highly robust root connection. This is due to the fact that the blade weight, along with all of the static and fatigue loads and the resulting bending moments, are supported at the root of the blade. In order to ensure the longevity of the blade throughout the desired design life, the root connection must withstand the operational loadings and survive the harshest of conditions. When designing these key structural components, advanced numerical models have been developed for tidal turbine blades, which includes damage prediction modelling and the effect of the environment on mechanical performance of the blade materials. Robust connections between these two sections and at the root, along with thick section composite structures, are often used to withstand these high forces and moments. For horizontal axis tidal turbine blades, these sections are primarily the spar, which runs the length of the blade, and the root connection. The high, variable loadings on tidal turbine blades cause high bending moment and shear loads, which need to be allowed for within the structural design of the supporting sections of the blade. However, the use of this material presents the developer with an additional challenge of a reduction in performance in terms of tensile and compressive strength due to water ingression, which needs to be accounted for in the design and manufacture stage of blade production. A key material technology that can be used to produce tidal turbine blades that won’t corrode in these submerged operational conditions is fibre reinforced polymers – for example, glass fibre reinforced epoxy. While the total electricity produced in Europe from tidal energy increased by 15 GWh to a total to date of 49 GWh. In 2019, the installed capacity of tidal stream energy in Europe reached 27.7 MW, which is almost four times as much as the rest of the world. During operation, these blades encounter high, variable loading conditions, including impact loadings, while being constantly submerged in water. One of the key components for many tidal energy converters is the turbine blades, whether they are vertically, horizontally or otherwise orientated. In order to achieve greater economic and sustainability targets, each key component of a tidal turbine needs to be designed, manufactured and operated as efficiently as possible. These advances aim to increase the likelihood of survival of tidal turbine blades in operation for a design life of 20 + years.Īs the global tidal stream energy sector moves closer to commercial viability, additional challenges are presented as developers strive to lower the levelised cost of energy in order to challenge the low cost associated with generating energy from fossil fuels.

The main novelty in this study comes with the challenges that are overcome due to the size of the blade, resulting in thickness composite sections (> 130 mm in places), the fast changes in geometry over a short length that isn’t the case for wind blades and the required durability of the material in the marine environment. Therefore, in this paper, a range of advanced manufacturing technologies for producing a 1 MW tidal turbine blade are developed. As a result, the main design and manufacture challenges are related to the main structural aspects of the blade, which are the spar and root, and the connection between the blade and the turbine hub. In order to avoid issues with corrosion, tidal turbine blades are mainly manufactured from fibre reinforced polymer composite material.

As a consequence of the harsh environment, the loadings on the turbine blades are much greater than that on wind turbine blades and, therefore, require advanced solutions to be able to survive in this environment. However, due to the harsh environment that tidal turbines are deployed in, a number of design and manufacture challenges are presented to engineers.

After wind and solar energy, tidal energy presents the most prominent opportunity for generating energy from renewable sources.

Tidal blade