Yes, wind farms sometimes make less energy during big storms

27 January 2025

More wind means more energy, except when the wind farm equipment must be protected or the grid balanced.

Protecting the turbines

Generators manage turbines to protect them from damage. The wind farm might “feather” the wind turbine blades, changing their pitch so they catch less of the wind. Or even “cut out” the turbines to avoid damage to them if the wind is particularly high. You can see this happening to the Ripple wind farm at Kirk Hill on Friday, as Storm Eowyn rolled in.

Screenshot from Ripple Energy dashboard: the kWh drops to zero as Storm Eowyn arrives at 10am.

Here’s what Ripple said about it:

“Output dropped a bit this morning; the Kirk Hill turbines reach maximum power at about 14 metres per second or 30mph, rotating at about 17rpm. However output starts to drop slightly as the blades pitch to protect the turbines in very high winds, and this is starting to happen with some of the turbines today, which is why output has reduced from max power. They only cut out when winds average 34 metres per second (75mph) over a 10-minute period - they can withstand gusts more intense than this whilst still operating. The highest gust recorded this morning was 100mph.

3pm - All the turbines are currently at 0MW output; they have automatically gone to this output to protect themselves due to vibrations resulting from the intensity of some of the gusts. Although average wind speeds have been below the threshold above which they would turn off, the gusts in this particular storm have been especially violent. The safety systems in the turbine mean that a few instances of the vibration warning can be remotely reset, but after this a manual reset is required at the turbine after a brief inspection. The RES and Enercon control rooms are liaising to determine if this is necessary, but a visit may need to wait until after winds have dropped to a safe level for a team to attend. The Enercon teams will also likely have a number of sites to attend to in the area.”

Balancing the grid

And if the grid has too much energy being generated, the Distribution Network Operator might curtail energy generators, which means “pay energy generators like wind farms to switch off”. And even where generators don’t have curtailment agreement, the DNO can still ask generators to constrain output or cut generation.

The reason why this happens: the grid must continuously balance current generation with current consumption because there isn’t a Watt mountain or electron lake that stores energy for later use. The Watt mountain is only just starting to be built, one utility-scale battery storage site at a time.

(Edit: is this an argument that renewables are bad? No. Look at the news: we still need to decarbonise our energy.)