Are wind turbines designed to fall apart so that they need to be replaced?

The engineering principle of design lifetime explained by a wind energy engineer.

Did an engineer design it like this on purpose? (Image: Shutterstock)

Sometimes when I am talking to people about wind energy, I will say something like “wind turbines are designed to last 20–30 years” and the person I’m talking to gets a kind of shocked look on their face (if they are pro-renewables) or a kind of “gotcha” look (if they are anti-renewables). I can see what they are thinking: are wind turbines designed to purposely fall apart? Perhaps so that “big wind” can rake in the profits as hapless wind farm owners have to buy new turbines? The truth is less dramatic than that. The principle of design lifetime is used by engineers for several good reasons, and it allows products to be more reliable and cheaper than if every individual component was designed to last as long as possible. Still not convinced? Read on and I will explain.

So, why not just design everything to last as long as possible? Isn’t that “good engineering”? I have worked the last eight years in the wind industry, so let’s investigate this idea using the example of a wind turbine. Since the wind itself is free, the main cost of wind energy is from purchasing the components and installing them. Once you have a turbine installed, it is very cheap to run compared to fossil fuel alternatives which need to pay for fuel. So the longer that the wind turbine can keep operating, the more energy you will get in return for that initial investment you made to buy the turbine and install it.

Wind turbines don’t need to pay for fuel, the main cost is from the equipment and installation (Author images)

So a longer life is better right?

The answer to that is yes, yes it is.

Longer lifetimes for wind turbines are one of the reasons that the cost of wind energy has fallen a lot over recent years. A decade ago it was typical for wind turbines to be designed with a 20 year lifetime, and now 30 years is not uncommon. So what has changed? Did it only just occur to wind energy engineers that a longer lifetime is better? Or were they sneakily designing turbines to fall apart after 20 years just so that the wind farm owner…