Albatrozz has developed a wind turbine technology to generate electricity at lower speeds. The brand new start-up was inspired by the behaviour of landing seabirds. By actively oscillating the tips of turbine blades, energy production can be increased by a few percents, says Geert van Ek from RG Projecten, together with the University of Groningen and EmpowerMi the founders of Albatrozz.

For which problem did you find a solution?

“Over a full year wind turbines regularly go offline because the wind speed is too low. Because there is not enough wind or because the turbines catch each other's wind. A typical wind turbine is designed to deliver full power at higher wind speeds. On land, half of the year wind speeds are lower than required to deliver full power. At sea the situation is slightly better, although it concerns al lot of time too, especially now wind farms are installed closer together. The lower the wind speed, the less electricity turbines produce. Until the moment the wind turbine switches off completely, because the wind contains too little energy for the drive chain. Depending on the type of wind turbine, this happens at wind speeds of 4.5 m/s and lower. We have a technical solution to deliver power even at lower wind speeds than normally feasible for that type of turbine."

What is the core of your solution?

“The University of Groningen discovered several years ago that if you actively oscillate wind turbine blades, you can get more power from wind at lower speeds. This discovery is derived from the behaviour of landing seabirds. Their wings are too large to move them up and down. They therefore wiggle with their wings. This oscillating movement can double the vertical force (lift) which is very useful at low travelling speed. We apply the same principle to wind turbine blades. Simply put, this can be demonstrated by cutting the last 2-3 meters of a turbine blade and providing it with a rotation shaft and an oscillation drive. The tips need to rotate around 10 degrees. Because they are thin and flexible, this requires little energy. The frequency varies, depending on the rotation speed of the blades, from 0.5 Hz up to 5-10 or perhaps even 15 Hz. Thanks to this oscillation, the air flow exerts greater force on the blades, so that they continue to generate power even at lower wind speeds. At higher wind speeds the system switches off and the wind turbine will deliver power as per original power curve for that turbine. "

What is so groundbreaking about your solution?

“Most applications for increasing the efficiency of wind turbine blades are static: dragon tails, triangles or pins in the blades to improve aerodynamics or aeroelastic behaviour. We are the first to apply a dynamic, active drive in the blade itself. That is the only way to maximize efficiency at lower wind speeds. And that is precisely where a lot of profit can be made. You do need an active system to harvest the additional lift and to prevent stall. We have succeeded in retaining the lift force and thus preventing the pressure from falling away. This is the first technical application with such an approach. "

What are the benefits of your solution?

“Thanks to our innovation, suppliers and owners can produce a few percent more electricity with the same turbine: the operating time of wind turbine will be increased – the cut-in speed is lower so it will deliver power more hours per year - and the wind turbine delivers more power at lower wind speeds. Considering that a wind farm of 700 MW yields around 1 mln EUR a day, every percent more is a considerable amount. In addition, the electricity price rises at lower wind speeds, as supply decreases. This makes our solution commercially even more attractive. ”

How far are you now?

“We have performed tests on flow tanks and we have developed a scale model of 1.5 meters and tested it in a wind tunnel. These tests confirmed and exceeded our modelling results and have proven that the principle works. Now we plan to demonstrate the effect on a pilot scale. We are planning a modification of an existing commercial wind turbine of 250 kW – 2,5 MW. We want to realise this together with partners from the wind industry. There is a lot of interest from wind farm owners, turbine suppliers and R&D companies. ”

What are your challenges?

“Robustness and performance. We must demonstrate that the principle also works in practice. That the system is reliable and runs smoothly without negative impact on availability. In addition, the modified blades must generate so much more electricity that this outweighs the cost of the drive. The best option is to integrate our innovation integrally into the design of new wind turbines, but for the time being we are aiming to adapt existing blades. The industry has ample knowledge and capacity to develop and optimize this for future applications."

What are your next steps?

“We plan to sign a consortium agreement for the pilot in August 2019 with a combination of partners who want to support the pilot project with their knowledge and practical commitment. We want to have a wind turbine operational in the course of next year. We will closely monitor the performance so we can share the results which will be ratified by an independent authority. Ultimately we want to offer this innovation to the market under license. Onshore wind is the most obvious, because of the lower wind speeds, easy access and existing infrastructure. However, we certainly see potential for offshore wind.”

What is the added value of Offshore Wind Innovators?

“As a consultant I have been involved in wind farms such as Gemini, Westermeer and Rentel windpark. Thanks to this network, we are already talking to potential partners. Offshore Wind Innovators can support us in expanding our network and increasing our awareness in the wind industry. The more suitable companies we can mobilize, the better. "

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