SSE Renewables has turned to the aerospace industry to develop a new way of modelling wakes in offshore wind farms.
Measuring wake losses - when wind turbines create a wake that reduces the wind available for downwind turbines – is a vital part of the design of offshore windfarms.
Now SSE Renewables have teamed up with the Unviersity of Bristol’s Department of Aerospace Engineering to develop new ways of modelling wakes in a state-of-the-art wind tunnel.
Given the relative youth of the offshore wind industry, there are few real-life studies on the impact of wake turbulence, which can differ greatly from onshore wind farms. As such, developers rely heavily on modelling to assess the impact of design choices and any flawed analysis can result in significant financial implications.
In the SSE Renewables project, which ended late last year, plastic porous discs mounted on a flat plate were used to represent the individual turbines and, with the wind tunnel activated, the drag on these discs was measured and used to indicate any loss in energy production due to the wake interactions.
Paul Housley, part of the SSE team working on the project said: “Accurately predicting wake losses is crucial to offshore wind farm design where it is important that the spacing between turbines is small enough to allow a project of sufficient MW, but large enough for the wind farm to be efficient. Both these factors have a direct impact on CAPEX and ROI of any project.
“The locations of the individual turbines can be positioned to optimise their production. Even a 1% improvement leads to tens of millions of pounds of additional income over the wind farm lifetime.
“It is far more practical to model the turbines in a large wind farm using static porous disc than with tiny rotating blades. The design of the pattern of holes in each disc is crucial and so we used a precision laser cutter to drill these holes quickly and accurately.”
The wind tunnel facilities, technical expertise and manufacturing for the research were provided by the Department of Aerospace Engineering at the University of Bristol.
SSE has begun to successfully validate the technique using production data from operational wind farms and predictions from computational fluid dynamics (CFD) modelling, which is more commonly used in the aerospace and automotive industries. A continuation of the research in a larger wind tunnel is planned.
Paul said: “We are encouraged by the results of the initial study and are looking to increase the scale of the project to further validate our findings. Even marginal improvements in this area could optimise the efficiency of offshore wind farms.”