Radar could protect birds from deadly wind farms

The impact of wind farms on migratory birds is well-documented AFP

Each year, millions of migrating birds fly over Switzerland – but for some, the journey ends in the blades of a wind turbine. A Swiss company has made special radar which could help prevent collisions and become a key element in wind farms.

This content was published on September 19, 2013 - 11:00

“It manages to pick out a swarm of mosquitos from a distance of five metres.” Urs Seiffert, manager of the Swiss BirdScan radar project, has no doubt about the radar’s potential. But he is not interested in insects – instead, he’s pinpointing the migrating birds that fly twice a year over Switzerland.

“There are tens of millions of them which move in a homogenous way. The aim is to avoid collisions with wind turbines,” he said.

The BirdScan radar scans the sky above the wind farm, explains the engineer, who is also the general manager of an energy consultancy. “It’s able to differentiate between different species of bird. But that’s not what we want,  we’re more interested in measuring the density of birds (to detect them better).”

The Swiss Ornithological Institute in Sempach is also participating in the project, which is still in its realisation phase. The institute itself has been using radar to study bird migration for 40 years.

“BirdScan’s particular feature is that it’s automatised: when the density of birds rises above a certain threshold, the wind farm stops working,” ornithologist Felix Liechti told

Birds and bats

The impact of wind farms on birds is has been known for some time and has been documented in numerous studies, Liechti says. “The construction of wind farms leads to a change in habitat: some breeding species may be affected. The biggest danger is, however, collisions with turbine blades. This is a risk for both birds of prey which are nesting or looking for food in the vicinity and for migrating birds.”

In Spain, wind turbines kill between six and 18 million birds and bats a year, according to the national ornithological society SEO/BirdLife. In North America, tens of thousands of birds of prey end up in rotor blades each year, including the highly symbolic American bald eagle.

But supporters of wind energy say the numbers can be relativised, adding that turbines aren’t actually the main cause of bird mortality. Most birds are killed flying into building windows or fall victim to cats, pesticides or road traffic, writes parliamentarian Isabelle Chevalley, president of the Swiss association for the promotion of wind power, Power (Suisse Éole) in her book Wind Power, Between Myth and Reality.


The precise effect of wind farms on the development of avian populations is not known, concedes Liechti. “Each species is a separate case and there aren’t any statistics in Switzerland. Nevertheless, it would be wrong to think that a couple of dead birds don’t make any difference at all,” he warns.

In the case of the bearded vulture, he explains, just two more victims a year would make the difference between a stable population and one that’s in decline.

Difficult cohabitation

A map showing potential conflicts between wind farms and avifauna drawn up by the ornithologists at Sempach reveals another important factor: that most suitable locations for wind farms are often situated in bird migration corridors. According the deputy president of Suisse Éole, Bastien Girod, as quoted in the Tages-Anzeiger newspaper, 60-70 per cent of planned wind installations in Switzerland are in sensitive areas.

For its part, the Federal Environment Office has now put a series of principles related to the authorisation procedure for wind farms into consultation.

“The idea is to draw up a practical manual to best assess the impact on fauna, in particular on birds and bats, and to thus be able to recognise potential conflicts,” explains Reinhard Schnidrig, head of the office’s Wild Animals and Forest Biodiversity Section. “It’s not about drawing up a specific law on birds.”

The content of the document has not been made public, but according to BirdScan’s Seiffert, “the protection of avifauna is becoming increasingly important (in government policy)”. Seiffert foresees two possible scenarios: stop the wind farm during the migration periods (a few weeks in spring and a few in autumn) or using an automated system like his that switches on and off, which is controlled by radar.

The radar’s advantage is that is reduces the periods of inactivity, so that instead of the wind farm being shut down for several days in a row, it might only be inactive at night, when most migratory birds would pass over.

“We have calculated that BirdScan could would result in the period of inactivity dropping from 300 to 100 hours a year,” says Seiffert. 

Swiss wind farms

In Switzerland there were 33 wind farms in operation as of March 2013, which last year produced 88 gigawatt hours of electricity This is about the same as the annual electricity consumption in 24,640 households.

Wind power accounts for around 0.2 per cent of electricity used in Switzerland; the European Union average is seven per cent. The countries at the top of the list include: Denmark (27 per cent), Portugal (17 per cent), Spain (16 per cent), Ireland (13 per cent) and Germany (11 per cent), according to data for 2012 from the European Wind Energy Association.

Italy (5 per cent) and France (3 per cent) are below the European average. The United States produces 3.8 per cent of its energy through wind power.

The first wind energy facility in Switzerland was put into operation in 1986 in Langenbruck, canton Basel Country. The largest wind park is on Mont-Crosin in the Bernese Jura with 16 turbines.

To promote wind power and other renewable energy sources, an instrument came into force in 2009 that covers the difference between the production and the market price and guarantees producers of “green power” a price that corresponds to their production costs.

In its Energy Strategy 2050, the Swiss government said that wind farms could produce 4,200 gigawatt hours of electricity a year.

For its part, the Swiss association for the promotion of wind power, Suisse Éole, estimates that 9,000-11,000 gigawatt hours of electricity could be produced per year, equivalent to around a sixth of annual electricity consumption.

(Source: Federal Energy Office, Suisse Éole)

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Interesting solution

Schnidrig finds the bird radar a “useful method” because it recognises bird migration frequency and can better anticipate the risks. “It’s a good solution both for wind power and protection of birds,” he says.


For the Swiss Association for the Protection of Birds/SVS/BirdLife, the radar still has to prove itself, but it nevertheless could be “an interesting instrument”.

“We think it should be obligatory,” said its deputy director François Turrian.

But it should not impede the need for careful and sparing approach to wind farms, added Turrian. “The zones of great biological value and migration sites should not be included in the planning phase.”

Suisse Éole is aware that wind farms can sometimes cause a problem for migratory birds and is in favour of protection measures. But there are not many sites in Switzerland where it would be suitable to use radar, it said.

“Making it obligatory for all the installations would therefore not be the solution,” the association told in a written response.

“Wind power substantially contributes to reducing CO2 emissions and thus to (reducing) the effects of climate change, which according to BirdLife International threaten 75 per cent of European bird species,” it added.

Radar test

Swiss BirdScan will start testing in the field at the beginning of 2014. The planned wind farm in Grenchen in canton Solothurn, which should open in 2015, will be the first to use this technology.

According to the local energy provider SWG, which has invested CHF35 million ($38 million) in the project, the cost of the radar – around CHF350,000 – will be amortised within a few years.

“For a big installation, this is just a trifle,” said Seiffert. “For a small price, you can make a big contribution to bird protection.”

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