How Dangerous Is Ice Throw from Wind Turbines?
In short: Ice throw is theoretically possible, but in practice very rare — fewer than a dozen documented damage cases nationwide over 15 years. Where traffic routes or buildings lie within throw range, an ice build-up detection system with automatic shutdown is mandatory.
How far does ice fly?
There are two rules of thumb (per Seifert / BWE — German Wind Energy Association):
| Scenario | Formula |
|---|---|
| Ice fall at standstill | 1.5 × (rotor diameter + hub height) |
| Ice throw during rotation | Blade tip speed + 1.5 × (D + H) |
For a 200 m turbine this works out to several hundred metres. The exact throw distance for your turbine is calculated by the ice fall throw distance calculator.
How is the hazard prevented?
Modern turbines have an ice build-up detection system: sensors on the rotor blade or vibration analysis detect ice formation and shut the turbine down automatically before dangerous amounts can form. This reduces the safety distance to the standstill value.
- Providers: Bofin (vibration analysis), Eologix (blade sensors), Wölfel iSpin
- Cost: 8,000–15,000 EUR per turbine (also available as a retrofit)
- Mandatory: where traffic routes, residential development or hiking trails lie within throw range
When is an ice fall report required?
In the BImSchG (Federal Immission Control Act) procedure, an ice fall report is required as soon as objects worthy of protection lie within the throw range. It assesses the site risk (icing frequency based on DWD — German Weather Service — climate data), calculates the throw distance and defines protective measures.
Frequently asked questions
As a resident, do I need to fear ice throw?
No, provided your house meets the approved minimum distance. This is chosen so that the house lies outside the throw range — or the turbine shuts down on ice build-up.
Does the turbine shut down completely in winter?
No — only when ice actually builds up. Detection is event-driven, not seasonal. Yield loss from ice-related standstill: typically 1–5 % depending on the region.
Are there warning signs?
Yes, warning signs are put up along paths within the throw range. In exposed locations, paths may be temporarily closed in winter.
Ice throw from wind turbines – throw distances, frequency and ice build-up detection