Wind farms are not always built at the windiest sites

Fredrik Hedenus

Historically, wind farms have not always been built at the windiest sites. Rather, the placement of wind power installations often seems to have been somewhat random, according to a study from Mistra Electrification that looked at almost 30 states and countries. Moreover, the density of wind power in Swedish municipalities is often much lower than in many other regions.

– Sweden is a geographically large country that is sparsely populated. That is a relatively straightforward explanation as to why wind power density is low, says Fredrik Hedenus, who is Professor at Physical Resource Theory, Chalmers University of Technology.

During 2022, he together with co-workers published a paper titled Historical wind deployment and implications for energy system models, which covered 28 states and countries in Europe, the Americas and Australia. The study found no evidence of a concentration of wind power installations at the windiest sites, as is frequently assumed in energy system models.

– We found that wind power rarely has been deployed at sites with an average wind speed <6 m/s. However, we didn’t find any evidence for a strategy that exploits sites with lower wind speeds only when windier sites are already exploited. Exactly where wind power has been allocated seems to depend pretty much on local and temporary considerations, concludes Fredrik Hedenus.

The study shows that the annual level of wind power production in Sweden is 62 MWh per square kilometre. This is low compared to the levels in many European countries, such as Denmark (379 MWh per square kilometre), Germany (367), and Belgium (427). However, it is higher than in Finland, which produces 24 MWh per square kilometre. The average wind power deployment density in municipalities seldom exceeds 0.5 MW per square kilometre.

– In Sweden, the three most densely deployed municipalities produce between 0.2 and 0.3 MW per square kilometre, and most Swedish municipalities have wind power deployment densities, of <0.1 MW per square kilometre. In other countries, such as Germany, many municipalities have higher wind power deployment densities, says Fredrik Hedenus.

In Sweden, one argument in the public debate is that wind power should be built in cities like Stockholm instead of in the countryside. What is your opinion about that?

– Well, the total amounts of land in that type of area in cities are quite small, so the total amount of energy that could be generated is also small. However, it is interesting in terms of political and social acceptance. In Sweden, wind power has become a polarizing issue, and this could be a sign of that.

Have you found an explanation as to why wind power densities vary so much?
– No, we haven’t. We have looked at factors such as population density, political preferences, and other underlying variables, but we haven’t found any clear explanations. In some cases, wind farms have been built in quite densely populated areas. This will be a topic for further research. Within Mistra Electrification, we will now try to find out why certain municipalities accept more wind power than others.

“Historical wind deployment and implications for energy system models” can be found here.