EWEA Blog - Wind resource assessment results: how accurate can we be?

The wind is not the same everywhere, every day. It can vary depending on the landscape, the altitude and the climate. A turbine on a mountain in Switzerland will not have the same wind conditions as a turbine on a delta in Italy. Yet for wind energy developers and investors, knowing as far as possible how much energy a planned farm will produce – ‘resource assessment’ – is crucial.

“Resource assessment determines whether your wind farm will make money or go bust,” says Will Barker from ZephIR. “An accurate assessment means more profit and less risk for the investor.”

“If you get the resource assessment wrong, there’s uncertainty for manufacturers and financiers”, agrees Stefan Ivanell from Gotland University.

What’s more, as wind turbines evolve –getting taller and with larger rotors – measuring the resource becomes even more complex. And what impact does one wind turbine in a wind farm have on the wind that blows over the other turbines?

Well over 200 people – including those quoted above – attended EWEA’s most recent technology workshop, in Dublin on 25-26 June, to find out about the latest developments in this technical field.

The highlight of the workshop was the results of an ‘assessment comparison exercise’. Prior to the workshop, 60 teams from 56 different organisations in 17 countries had downloaded from EWEA’s website all the information required to perform an assessment of the energy production of a real 22 turbine wind farm in eastern Scotland owned by RES. Their estimates were compared with each other and contrasted with the “real” figures – and the results were presented in Dublin.

The teams’ estimates of the power production averaged 75.7 GWh (the range went from 64 to 91 GWh). The real energy production – observed over five years – was 76.25 GWh – a difference of just 0.1%. The six teams with the most accurate estimations used a range of models to get their results.

“Wind resource assessment works if you do it right!” concluded Niels Gylling Mortensen from DTU Wind Energy, who presented the results. However he pointed out that there is always an element of the unknowable “human factor”.

The Dublin workshop was organised by EWEA with the Irish Wind Energy Association. EWEA’s technology workshops are organised in response to requests from members. The next workshop, on wind power forecasting both onshore and offshore, is entitled ‘From R&D to commercial offering – a 360° view of present and future’ and will be held on 3-4 December 2013 in Rotterdam, The Netherlands. It is organised in association with the Anemos Consortium.

More information: www.ewea.org/events/workshops