Engineering

Buoy measures windspeed with laser beams

Where in the sea the wind blows hardest? Wind park planners can find out in the future faster – with a buoy by researchers of the Fraunhofer Institute. The yellow colossus measures the wind strength with laser beams.

Prior to the installation of offshore wind turbines, planners need to find out where the wind blows most. “Continuously higher wind speeds at sea can compensate for back the enormous investment for the construction and grid connection”, Claudia know Rudolph, scientist at the Fraunhofer Institute for wind energy and energy system technology (FhG-IWES) in Bremerhaven. The problem: wind measurement masts, which measure the wind speed at a height up to 100 m, are quite cumbersome to install and cost-intensive. There must be a cheaper solution, the researchers have thought.

Yellow buoy shoots laser beams into the sky to measure windspeed with laser beams

New hero of the wind measurement is a yellow buoy: you is 8 m long, 2.55 m wide and proud 4.9 t hard. It is similar to the classic buoys, which are more than 30 years in the North Sea in use thus visually. The actual feature on board is a laser instrument called light detection and ranging (LIDAR) – fans of autonomous driving is known it maybe out of the self-driving Google car.

“LiDAR systems send pulsed laser beams in the atmosphere. These are reflected on particles in the air, the aerosols”, says Rudolph. “From the frequency shift of the backscattered signal the wind speed and direction in the corresponding measuring height is calculated.” So far, this was impossible for drinking buoys. For this reason, the researchers have developed a correction algorithm which compensates the movements of the buoy in the water.

Boje much cheaper than wind measurement masts

The buoy should save a lot of money in the future wind park planners. “On the high seas, the LiDAR buoy is a real alternative to wind measurement masts, determine the wind speed only at a height of 100 m,” Rudolph says. She can be namely everywhere quickly installed at sea. The cost of this be allegedly five to 10 times less.

Also the maintenance is not nearly as expensive as a measuring mast. This is because among other things, that the LiDAR instrument is enclosed in an aluminum housing with special glass. There, it is protected from salt water and extreme environmental conditions at sea. The operator must not even worry about the power supply. As the buoy is equipped with three small wind turbines and solar panels that store electricity for a week operating in three gel batteries. The data transfer works via Wi-Fi or satellite.

Promising tests in the North Sea

Promising results in initial tests in the North Sea: in the vicinity of the uninterrupted, Alpha Ventus, 45 km off Borkum, scored a test buoy laser beams in the vicinity of the measuring mast Fino 1 in height. The values of measurement mast and buoy it agreed to 99.7%. With this demonstration, the scientists want their development the offshore company Consortium Carbon trust offshore wind Accelerator (OWA) present – a non-profit corporation with the mission to promote the transition to a climate-friendly economy. “Meet the criteria of the OWA, get a pre commercial status”, says Rudolph. “This is an important signal to our potential customers. It shows that our system is fully operational.”