The AIRE project is dedicated to the development of innovative software models, incorporating novel technologies. These models will factor in long-term wind turbine operations and account for extreme weather conditions (in diverse terrains and altitudes). AIRE is gathering valuable data from four experimental sites and four commercial wind farms. This is a blog series where all the eight sites that are part of the AIRE project will be presented. This entry will introduce the experimental site managed by the project partner DTU in Denmark
Risø observational site
The Risø site at the Technical University of Denmark (DTU), stands as a key contributor to the field of wind energy research. Established in 1958 and integrated into DTU in 2007, Risø DTU is dedicated to sustainable energy solutions.
Location
The Risø site is located on the shore of the long and narrow bay of Roskilde, which extends from the Kattegat Sea in the North down to the city of Roskilde, located on the island Zealand in Eastern Denmark. In the most common, Westerly, wind direction at the site, the bay extends 5-7 km in the immediate vicinity of the site. To the East, North, and Northwest, the coastline to surrounding seas is approximately 40 km away, whereas it is at approximately double that distance for the Southwesterly and Southerly directions. Due to the close proximity to either the coast or the local water surface, the site is categorized as coastal, but depending on wind direction and observational height, the patchy agricultural landscape may dominate the measurement footprint.
Figure 1. Risø’s location.
Test site characteristics
The most prominent atmospheric measurement feature at the site is the 123m tall Risø mast. At the top of the mast, there is a small measurement platform from which a thin tubular mast extends up to 125m. The red and white Risø mast is one of the oldest research infrastructures in Denmark with observations starting in 1958. In 2020, the measurement facility was improved by tiling the surface near the mast and improving the data logging infrastructure. The platform is intended both for ground-based in-situ and remote-sensing observations via the EU infrastructure project ACTRIS.
The mast has six levels of cup anemometers, two levels of temperature observations as well as pressure relative humidity, and incoming shortwave radiation measurements. It is currently being re-instrumented with eight levels of sonic anemometers.
The mast is part of the extensive multi-mast infrastructure on the access-restricted Risø campus of the Technical University of Denmark, where the Wind Department runs a test-site for small wind turbines. Hence, the site is an important infrastructure both in the context of air pollution and wind energy.
Figure 2. Left: The Risø met mast. Top right: anemometer, pyranometer, wind vane and a view over Roskilde fjord. Bottom right: Doppler wind LiDAR placed at the top of the tower.
Role in AIRE project
In the AIRE project, the site is an important part of Work Package 2 and provides data to the datahub for the other Work Packages. The focus of the observations for AIRE are on wind profiles in the height range of tomorrow’s tall turbine as well as on precipitation that cause leading edge erosion on the wind turbine blades. Concerning the wind profile, we reach beyond the height of the Risø mast, by mounting a remote-sensing Doppler wind LiDAR on the small platform at the top of the Risø mast. In this way, the measurement range is tripling, with observations up to 370m.
Concerning precipitation, we measure the droplet-size droplet-velocity matrix with two disdrometers, as well as bulk precipitation with a so-called tipping-bucket rain gauge. These instruments are located in close proximity to each other near the bottom of the mast on the platform. To understand the precision, accuracy and instrumental limitation of all precipitation observations, a number of calibrations have been performed and analyzed. These experiments will be used to define the quality-controlled dataset, which is an ongoing activity for involved staff at all the experimental platforms.
Figure 3. Calibration of tipping-bucket rain gauge. MRR-PRO – and two disdrometers on the platform next to the base of the mast (last 2 images).
In addition to the in-situ precipitation observations, a Micro-Rain-Radar (MRR-PRO) is located at the site. This instrument measures the reflection of emitted radar pulses at 25m vertical resolution up to 3200 m. Observations from the MRR allow to detect precipitation events prior to their occurrence at the surface, which is an interesting feature of potential great value concerning wind turbine and wind farm operations. Such information allows the wind turbine operator to reduce the rotational speed of the wind turbine, which should reduce the erosion damage on the wind turbine blades. In this way, the need for costly repairs with associated power production losses is also minimized and the lifetime of the turbine may be extended.
Conclusion
The AIRE project’s innovative approach to extending atmospheric measurement capabilities at the Risø site marks a significant advancement in wind energy research. By predicting environmental impacts and optimizing operations, these efforts promise a future of more durable and sustainable wind energy.
Author: Ebba Dellwik
Editor: Lucia Salinas
March, 2024
