If it sounds too good to be true: Samsø, a “self-sufficient” island

Is it possible to be powered 100 percent by alternative energy sources? The authors of the Greenpeace brochure “9 myths about the German Energiewende debunked” have no doubts about it. They gave the example of the Danish islands Samsø and Ærø which according to them achieved just that. This is how they explained it (translated from Dutch):

samso aero

The Danish islands Samsø and Ærø (in total 10,000 inhabitants) run entirely on renewable energy: all electricity is generated by wind turbines and 70% of its heating comes from solar plants, small-scale biomass plant settle the difference.

If these islands are indeed only powered by renewable sources, then that is interesting. If these islands are solely reliant on alternative energy without support from fossil fuels, then this would be a strong case for a transition. But if their electricity is only powered by wind, then how do they manage to deal with the intermittency? Okay, I can understand that wind blows stronger on those islands than inland, but even then it will be a challange to use that intermittent power in a continuous working system. So how do they balance that load? Or do they only use electricity when it is available?

Also the heat generation process was not clear to me from this explanation. Did they mean that 70% of the heat was generated by solar panels? Then how could they do that in the middle of winter when there is the highest need for heating and just 7 hours of daylight? Or did they mean that 70% of its heating is generated by solar plus biomass? Then how could they be running 100% on alternative sources? Finally, what about transportation? Isn’t there a need for that on those islands? Or is that all powered by animals, biofuels or electricity?

A lot of questions, so I began reading about those islands with the focus on how they overcome intermittency when their only source of electricity is believed to be the wind. Every source that I looked at said basically the same, those island are 100% powered by alternative sources and a lot of cheering is going on:

First island in the world to be completely powered by renewable energy

100 percent transition to self-sufficiency through renewable energy

The island is 100% powered wind-generated electricity

A 100% Wind-Powered Island

Meet Denmark’s First 100% Renewable-Energy Island

Samso: World’s First 100 Percent Renewable Energy-Powered Island

Samsø the energy self-sufficient island

The Danish haven of Samso has become one of the first industrialised places on the planet to qualify as being totally energy self-sufficient

I didn’t find any critical articles. Apparently, the transition to alternative sources was completed there and it was all positive. The people of those islands even managed to do so in less than a decade and they are simple people, not green idealists.

Something is not right here. If this is a truthful representation of the facts and the transition from fossil fuels to wind and solar is such a positive and painless story, then why is not the rest of the world jumping over each other to make the transition?

The first crack in this overly positive story came when I gathered the information of where that 100% wind energy came from. Somsø has 11 onshore turbines of 1 MW, 10 offshore turbines of 2.3 MW and in 2013 it had also 12 micro-turbines. That is quite a lot for a population of about 4,000 and a yearly consumption of about 25,000 MWh. Just a back of the envelop calculation:

  • Onshore: 11 x 1 MW = 11 MWh at 22.5% (capacity somewhere between 20-25% 1) = on average 2.48 MW per turbine
  • Offhore: 10 x 2.3 MW = 23 MWh at 42.2% 1 = on average 9.71 MW per turbine
  • Together that is 2.48 + 9.71 = 12.19 MW x 24 hours x 365 days = 106,749 MWh per year

1 Onshore and offshore capacity factors

They are producing more than four times the amount of electricity that they need! That is the key to this “success” story. They doing basically the same as the Germans do. They are exporting their problem to mainland Denmark and consider it an achievement. That is the reason why I didn’t find anything on how they balance intermittent energy: nobody talked about overcoming intermittency, because Samsø doesn’t even try to overcome intermittency… It also gives the possibility to declare that they are “neutral” for the use of fossil fuels in for example transportation, because this overproduction “compensates” for all that. Mathematically this makes sense, but it has nothing to do with reality.

In reality Samsø is self-sufficient in the sense that it produces more power than it needs, but it isn’t 100% powered by alternative sources and isn’t independent from fossil fuels. They depend on the connection to the mainland in order to maintain the stability of their grid and fossil fuels are still used. How would they fare if the the mainland cable would be disconnected? How would they then cope with overproduction when wind is blowing hard? Or when there isn’t enough wind? That would be the proof of the pudding.


3 thoughts on “If it sounds too good to be true: Samsø, a “self-sufficient” island

  1. Edward Hurst

    Scotland seems to be aiming for the EQUIVALENT of 100% of its electricity production through exports to England. (And impose no upper limit) To achieve this they promote the installation of limitless turbines with the resultant negative impacts.


    1. trustyetverify Post author

      Not heard about it yet, but I am not surprised. Several countries are eager to follow the path of Germany and Denmark. It is cheaper to overproduce and export the overproduction than to balance the output of the intermittent power sources. But if everyone is doing that same thing…


  2. Mjw

    One turbine for every 121 people, extrapolate that the the U.S. And you have one wind turbine for every square mile, leaves just enough room to squeeze in the solar panels.



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