Baseload, Hydropower, Solar

Preventing Bird Deaths at Solar Power Plants, Part 2

Part 1 of this article lays out the problem of bird deaths at some CSP power plants and begins to offer some solutions. Part 2 gives more solutions and explains how some of the companies involved plan to solve the problem.

Mobile Radar Plus Bio-acoustics

DeTect Inc. uses advanced bird radar originally developed for the U.S. Air Force and NASA to detect incoming birds, which then activates high-powered focused speakers that aim digitally recorded distress calls and other nuisance sounds up into that airspace.

The combination of radar and the acoustics — a selection of distress calls and also other alarming noises like sirens — is able to drive birds away along a specific trajectory over long distances and can simultaneously be tracking multiple targets.

Anderson says combining radar, mobility, and digital recordings of distress calls — and also other alarming noises like the sound of helicopters — is able to drive birds away along a specific trajectory over long distances.

The sound can affect even small birds up to a nautical mile in the air, and create a bubble around the risk zone that detects birds instantaneously to send the sounds in real time. The radar can scan every three to six seconds, and fire the sounds in one zone, then if it picks up birds heading towards the other tower, that zone deterrent would go off as well.

Because of the enormous areas they can cover, DeTect units are used to deter birds from coal, oil and gas waste ponds throughout the U.S. and Canada.

“We have effectively reduced the bird mortality to zero at those sites,” Gary Andrews, General manager at DeTect said. “Once birds [start] coming into a zone we don’t want them to go into, the radar detects them and activates the deterrent devices to deter them from the area and move them away.”

The combination of bird radar and focused bio-acoustics introduces the element of randomness and surprise. The distress calls or predator cries play in various combinations and in various volumes which helps reduce the risk of habituation.

“Habituation was a common problem with conventional bird control devices like propane cannons and omni-directional speakers,” he said. “It’s not been an issue with these long-range acoustic devices for a couple of reasons. Our computer system that controls the radar and speaker devices is designed to vary the bird distress sounds and other nuisance noises being played.”

The device also creates a pressure wave that is much stronger than a normal acoustic speaker system. “So the bird is not only hearing the sound but it is also feeling it. And that also reduces habituation.”

The CEC wants to be sure that any method chosen to alter flight paths won’t have the unintended consequence of diverting birds towards the second heliostat field or towards the flux field of the second tower.

Andrews said that is not difficult.

“It’s fairly straightforward and not that complex,” he said. “In fact solar plants are a little bit easier because we’re deterring the birds in flight, as opposed to trying to track them coming down to land on the ground.”

“We surround a site with enough radar so we have full coverage and each area we want to cover has an array of bio-acoustic emitters that can send a beam of sound up to a kilometer away. If you’ve got birds moving from one area to another area that you want to keep them out of, the radar detects them approaching the other area and deters them from that area also.”

Working Dogs 

Border collies have long been bred for the physical stamina it takes to herd sheep or cattle, an all-day occupation that typically involves running for miles every day and sprinting across long distances.

To herd birds away from the danger of solar flux in a particular area, working dog breeder Jinnie Gailey of Ohutu Kennels said a cattle border collie mix would be ideal. 

She recommended starting with a border collie bred for working with cattle. While border collies that herd sheep use the “stern eye” to make sheep move, working collies bred for cattle roundup use chasing and barking.

“You want one that’s a bit looser, that wants to run and bark. You want a dog triggered by movement,” she explained.

Border collies have been bred for the physical stamina, persistence and endurance needed for herding flocks of sheep — an all-day activity that entails miles of endless running and sprinting.

For the most effective deterrent she would even cross a border collie with a hunting breed. “Anything that’s really barky” crossbred with border collie; for their work ethic and tireless devotion to the cause. “Because if they like the job you give them they will keep at it.”

“Border collies are sort of a pattern dog. If you give them a pattern that’s normally what they’ll stick to. They like to have a sort of track that they run.”

Because they would be running safely out of range on the ground, border collies could control the area close in to the towers and to the solar flux.

Trained Falcons or Hawks

Pierre Molina, VP of the Environmental Division of Falcon Environmental Services (FES) — whose company provides working birds like falcons or hawks trained to deter birds primarily from airports throughout the U.S. and Canada — recommends an integrated approach that would combine working birds with other deterrent technologies such as radar and bio-acoustics.

“We worked with several companies in the past, such as Accipiter Radar,” he said. “I only see finding solutions by using an integrated approach.”

In the case of CSP, he said the falcons would have to be out of range of the solar flux.

“The flux would be a danger to the control birds as much as for the wildlife,” said Molina. “They can be trained to avoid it, but it would be a challenge to make sure they are away from it 100 percent of the time. We would need to properly assess the risk involved, for our birds but also for the wildlife.”

Falcon Environmental Services also assesses wildlife risks, and prepares and implements wildlife management programs; approaching each task methodically, identifying the tools and the key performance indicators to measure the effectiveness and following up, making adjustments as needed, to ensure they meet the specified goals.

Sports arenas and recreational facilities use working birds like this falcon at Wimbledon to keep unwanted birds, like pigeons, away.

Molina suggested they could use working birds that would be predators familiar to the Mojave desert like the Peregrine Falcon, Red-Tailed Hawk and Harris Hawk.

But these are also trained working birds fed by their handler, so they would not threaten or degrade habitat values for Mojave fringe-toed lizards; ground nesting birds, and desert kit fox.

“The goal is to not cause more damage,” he explained. “Although this might look like the same challenges that we face when we need to control and manage birds at a large international airport, the challenges for this precise site need to be assessed properly.”

In their extensive experience working with federal and provincial or state regulators and with several industries, they have found this is the only way to perform an effective wildlife plan.

Many Good Options

All of these seem like good options for the humane and safe deterrence of birds.

BrightSource and Abengoa will work with the CEC Technical Advisory Committee (TAC) to decide on a particular combination of deterrent technologies and test it at Ivanpah in order to see results that will work for the CSP industry.

For example, while cannons and pyrotechnics have been demonstrated to be effective for dispersing birds in other applications, the CEC feels these may not prevent birds from flying at elevations where they are at risk from solar flux. But the chance of reducing these relatively small numbers of avian mortalities is very good.