Making sense of German wind energy

I thought it might be a good idea to meet with wind energy critics to hear what they have to say. But my experience told me otherwise. Perhaps I should have been warned. They are associated with a German organization called „Vernunftkraft“, which has „sensible“ in its name. How presumptuous! It should have been a red warning flag for me.

We recently published a paper that evaluated wind energy generation over the last 15 years in Germany. It was published by PLOS ONE, an open access journal so that everyone can get access to it (here is the link). I was already anticipating some responses to it before it got published. After all, wind energy is a highly polarizing subject. So we decided to issue a press release, as it helps us to explain what the background of this paper was and what the results mean (the press release is here). After its release, I got contacted by a few media outlets, they published it as news, and then I got some responses, by e-mail, or by phone. It is quite a typical line of events.

It is also quite typical that after we publish something on wind energy I get contacted by wind energy critics. In the past, we have published work on limits to wind power that are much lower than what others have said. There are good, physical reasons for us to say this, and these low limits become important at large scales, although we are currently nowhere close to such limits. But I got plenty of phone calls of people who want to use these findings to discredit wind power in general. Either because there are wind farms planned near their village, or because they find nuclear power cooler, or god knows why.

What I feel quite uncomfortable with is that by making physical arguments of lower wind energy potentials, I am being put into a wind critics box. I am not a critic of wind energy. In fact, I am all for renewable energy, as it is the only way out of the global warming mess that we are currently in. This is a logical response to counter global warming. And not just that, it is the logical next step into a sustainable future if human societies want to sustain their quality of life. The pressing question for me is how we can make the transition to a renewable energy future the most effective, and this involves, to some extent, questioning resource potentials for wind energy. Questioning the need for this transition to renewable energy does not even come close to my mind.

With regards to questioning wind resource potentials, in our most recent paper, for instance, we found out that we can explain the produced wind energy fairly well using wind fields from the German weather service and turbine information. Yet, what was produced was about 30% less than what was expected from the wind fields. Some of this we could attribute to turbine aging or to shading effects within wind farms. But the largest part we could not explain. I think this is quite important to know that actual wind energy generation is at least 20% less than the resource potential.

Another aspect we found is that wind speeds in Germany declined over the time period we evaluated at rates that are similar to those reported in the global stilling literature (e.g., see Wikipedia entry here). I do not know whether this trend continued in Germany in recent years, and the reasons for global stilling are also mostly unknown, at least in my opinion. But it is a trend that certainly does not help wind energy in the future to stay productive, and this is important to know. (Actually, we only noticed this because one of the reviewers specifically asked about such trends.)

Also, we could not find statistically significant indicators for decreased efficiencies of wind energy generation due to large-scale wind speed reductions that we would have expected based on our previous work. But this is mostly due to the fact that too many variables correlated with each other, so we could not identify the installed capacity of wind turbines in a region as a significant factor that led to reduced yields. On a qualitative level, it seemed to us that one may find such negative effects already in the northern and northeastern parts of Germany, but this would need more work.

So there is certainly more questioning, more work, and more research to be done to inform the best way to shift to renewable energy.

When the two wind energy skeptics then came recently to my office, they had something entirely different in mind. First, they pointed out that by being retired physicists from industry, they were very well qualified for the topic. But then, after they sat down on the sofa in my office, they demonstrated their “qualifications” by quickly turning into preaching mode. I felt like I had Jehova‘s witnesses sitting in my office. Instead of sins, they talked about the evils of renewable energy, and instead of paradise, they talked about the glory of brown coal. I just could not believe what I heard, stunned by the lack of science and rational thinking! It was hopeless. It did not take long for me to decide that it was time for them to leave my office.

It left me with a sense of frustration and that a transition to renewable energy does not just involve rational thinking, science and technology. It also involves using science to open up human minds beyond to what they are used to and to be able to envision the future. But on that challenge, it seemed that I have failed miserably.