Tidal power belongs to renewable energy sources meaning it cannot be depleted like fossil fuels can. Tides are predictable, and this predictability is also one of the advantages that tidal power has over other energy sources because rise and fall of tides are much more cyclic than random weather patterns. This predictability gives us knowledge when the tides will be in and out. Because of this, tidal energy brings a promise of a much higher efficiency than other renewable energy sources.
Tidal energy is therefore a young but very promising emerging business. Tidal energy is increasingly becoming a serious offspring in the world of renewable energy.
The fact that Airborne, in close collaboration with customers (co) designs and builds tidal blades for the Tidal energy systems makes us proud.
The way we produce with RTM technology contributes even more to the durability of the blades. Furthermore we believe that introducing the principles of hydrodynamic behaviour in relation to composite blades can bring additional drastic efficiency improvements. Institutes like MARIN in close collaboration with the business unit Marine make this happen.
It’s the ambition of Airborne Marine to become technology leader for Tidal blades
If we assume that tidal energy as a sustainable energy source will live up to expectations, a substantial part of households in the world will be supplied with energy generated from the tides by 2020. The number of turbines on the seabed would then have to grow steadily from several dozen turbines in 2015 to hundreds in 2020 to thousands beyond 2020.
In order to facilitate this growth and thus the transition from fossil fuels to sustainable energy sources, a future-focused approach to the engineering and manufacturing of the tidal blades that is suited for large scale manufacturing is essential.
Cost effective manufacturing of heavy loaded thick walled composite structures, as tidal blades are, is a challenge in itself. Let alone executing it on large scale with a guarantee of constant high quality. To give a point of reference; for 1 MW turbine on average 3 blades with a blade length of about 8 meter and a weight of about 2500 kg is required.
Airborne Marine’s approach to this challenge is to develop and apply advanced closed mould Resin Transfer Moulding (RTM) injection technology in combination with pre forming technology. We are confident that this is the most well-balanced solution to all important topics present. These topics are solved by Airborne as follows:
The injection of thick walled large structures in a one-shot-process that is highly industrialised is a challenging concept. Airborne’s dedicated research & development department (Airborne Technology Centre) is therefore essential in creating the opportunities for our game-changing manufacturing technologies. Through Airborne Technology Centre, we have built up significant experience on a wide range of process technologies, among which the mentioned Resin Injection Technology.
A major and ultimately decisive topic in today’s development of the growing Tidal Energy market is bringing the Cost of Energy (CoE) down.
Managing the CoE is a challenge tidal turbine manufacturers are facing today. The CoE of tidal energy should be at least equal to the CoE in today’s offshore wind energy industry.
Tidal turbines are positioned 20 meter below sea level in open sea. Easy and quick repair of it is therefore not straightforward. As a result, maintenance costs are an important factor in the total cost of ownership of tidal turbines. The reliability of the turbine system and reliable blades are therefore essential conditions for success.
Another factor to bring the CoE down is directly related to the efficiency of the tidal turbines.
The efficiency of the turbine depends partly on the performance of the blades of the turbine.
Because of this, Airborne Marine focuses its efforts in the tidal turbine blades design and manufacturing on enhancing their reliability and performance.
Airborne addresses the reliability of the tidal turbine blades from the very beginning of the concept design process.
Most current tidal turbine blades design is based on two shells bonded together, as is routinely done in wind turbine blade design. Seawater conditions however are dramatically different from the air in which wind turbines perform.
To date, it remains unknown how the dynamics that are present in sea water will affect the performance of adhesive bonds over a longer period of time. When applied in structural composite products such as tidal turbine blades, it remains unpredictable what the effect of enduring heavy loads and fatigue on the blades will be on the long term.
For this reason, Airborne Marine’s standpoint is that tidal blades must be designed without adhesives in order to maximize the reliability of the blades. Based on hydrodynamic and maritime engineering experience, Airborne Marine has decided to reduce the risks caused by adhesive bonding. The application of the sophisticated and new to tidal energy Resin Transfer Moulding technology (RTM) will reduce that risk featuring double-sided tooling for thick-walled structures.
RTM technology allows us to manufacture tidal blades as a single, integrated composite part.
As a result, Airborne Marine is able to produce cost effective tidal turbine blades that are reliable and high-qualitative on the long term.
In addition, by combining RTM manufacturing technology, automation and specific basic raw materials the true cost-effective mass manufacturing will be at reach.
Airborne Marine believes that this approach will bring the requested maintenance intervals of 3 to 5 years.
Performance enhancement can be realized when the loads present on the blades or shaft, can be transferred as smoothly as possible. An optimal blade-root connection with the hub/shaft that accommodates both the (structural) loads to be transferred and the geometry required for the best hydrodynamic (performance) behavior, will enable this.
With respect to high-performance tidal blades, Airborne Marine’s standpoint is that using embedded insert technology is the answer to facilitate both heavy loaded reliable blade design and efficiently performing blades at the same time.
With the concept that Airborne Marine is now developing and introducing, the potential of having so called Slender blade designs available is now becoming reality.
The CoRMaT project was a challenging project for me as a Project Manager within Airborne Marine. Since it was also the first Tidal project for Airborne as a company it was quite a heavy project and many challenges have been faced and overcome throughout the duration of the project.
The tidal energy market itself is in the first phase of exploration, with only a limited amount of functional demonstrator project deployed in open waters. The CoRMaT EMEC project, for our client Nautricity Ltd, was to manufacture a series of 7 blades which are to be tested at the EMEC test site in Scotland. It will be the first full scale tidal turbine for Nautricity. As such, they have limited knowledge on which exact requirements the tidal blades should meet. The project team helped out to define all requirements, using Airborne’s experience from other marine projects.
During the design phase of the blades, a series of geometry changes were necessary in order to make the blade design structurally feasible. These changes also influenced the tooling design and production, since more complicated tooling was required. This was not anticipated upfront and a Change of Scope was required.
We held a meeting with all involved engineers and production workers to investigate the impact for the project planning and budget. A plan was made to minimise the additional lead-time required up to tooling delivery. Since we had foreseen the delay in such an early stage and communicated it well to our client, the change in the blade delivery schedule did not have an effect on the overall project planning of the EMEC turbine.
In November 2012 we injected the first tidal blade, using our 1-shot RTM process for thick-walled structures. The mould opening was quite a special moment. All hard work of the previous months paid out after the ‘unpacking of the present’. The result was above expectations for a first product. We celebrated this event with a piece of pie, homemade by the project manager.Maarten Bach, Project Manager Airborne Marine