Designing Mortality Monitoring at Solar Facilities

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Addressing a need for wildlife monitoring at solar power facilities

The U.S. Geological Survey recently published an Open-File Report to assist wildlife managers in designing monitoring protocols to estimate bird and bat fatalities at utility-scale solar energy facilities.

Solar power tower surrounded by an array of heliostats
Heliostats - large, movable mirrors - reflect sunlight towards a central collector tower where the sun’s focused rays heat water, creating steam to drive a turbine. The turbine is connected to a generator that converts the mechanical energy of the turbine to electrical energy.Public domain

“Although significant advances have been made in monitoring protocols for wind power facilities, there remains a need for similar protocols that can be applied to solar power facilities,” said Manuela Huso, USGS research statistician. “This new report fills an immediate need for monitoring protocols at solar power facilities.”

Ms. Huso, along with scientists from the USFWS, adapted current wind monitoring protocols for the unique conditions found at solar facilities. Solar power facilities, unlike wind, are generally located in areas where the land is flat and sparsely vegetated. This makes it easier for sampling crews to find and count the birds and bats killed by solar infrastructure. The authors present case studies based on current monitoring practices in operational solar facilities to illustrate sampling techniques that could improve the capacity to detect impacted wildlife without substantially increasing monitoring costs.

“There is a critical need for a statistically sound mortality estimator relevant to solar power and we are developing one,” said Huso. “But, the estimator will need good quality monitoring data to give credible answers. Following the monitoring protocols described in this report is a good way to collect these data.”

Array of photovoltaic cells collecting energy from the sun
Photovoltaic, or solar, cells convert sunlight directly into electrical energy.Public domain

This report was prepared at the request of the U.S. Fish and Wildlife Service. Solar power is an important and rapidly expanding component of the U.S. renewable energy portfolio. It is a priority of the USFWS to better understand the impacts of renewable energy development on wildlife.