Master forsvar Christian Søndergaard

Supervisor: Tom Cronin, DTU Wind Energy

 Niels-Erik Clausen, DTU Wind Energy

Examiner: Jesper Munksgaard, HOFOR

The defence is a part of the Online Wind Energy Master

About the Online Wind Energy Master

The part-time master programme is scheduled to take two to four years, making it possible for participants to study while working. The participants come from all over the world and in August, the first participants graduate.

On Friday August 30, 2019, there will be a reception in B118 for the eight graduates. 

Abstract: Renovate, Repower or Remove; An Evaluation Process for Wind Turbine Owners Using the Case of a V47

In Denmark we have a ‘Year 2000 problem’. As can be seen from the graph below there was a massive spike in the instalment of land turbines in the years around year 2000. This means that of the around 4600 land turbines in Denmark, half of them are nearing their ‘technical design lifetime’. Many of the turbine owners of that time were either individuals (farmers with both land available and money to finance a turbine) or wind turbine cooperatives consisting of a number of individuals ‘crowd funding’ one or more turbines relatively near to where they lived.

They were not often professionals in wind power projects and although an enormous amount of knowledge from actual experience have built up over the years – this is not what they do every day and therefore this report tries to point out some possible directions, what to look for and their possible consequences in terms of moving on past year 20 of their turbines lives. Seen from a helicopter view, a land turbine owner has three obvious roads to follow, each with their individual pros and cons.

For the remainder of this report these roads will be named as follows:

  • Renovate – by this meaning both keeping exchanging larger parts as they break down seen as a cost benefit view and an upgrading approach trying to get more lifetime and/or produced energy out of the turbine.
  • Repower - Replacing old turbines with new ones is in many cases like starting over again – but new turbines are much larger and more complex and so is the approval process – is it worth the efforts?
  • Remove - For a 20-year old turbine it is often a matter of selling the turbine and maybe even the position. If the turbine is run to the end there is significant price to pay in removing the turbine and its foundations.


ons 28 aug 19
13:00 - 15:00



DTU Risø Campus
Frederiksborgvej 399, bld. 118, meeting room Poul la Cour
4000 Roskilde