Renewable Energy and Wildlife: USGS Research on Risks and Solutions

The renewable energy sector is expanding fast and diversifying the nation's power supply — but advancing it and conserving wildlife can conflict. The U.S. Geological Survey (USGS) researches those conflicts and develops workable solutions.

A growing footprint

Renewable power comes from wind, sun, plants (biomass), Earth's heat (geothermal) and water (hydro, tidal, hydrokinetic). In the past decade wind and solar have grown sharply: turbines feed grids in most states, and utility-scale solar is multiplying in the Southwest and South Atlantic. Many large projects sit on undeveloped public land, often in or near wildlife habitat, so ecological science helps guide siting and operations.

U.S. grid-connected wind and solar generation, 2004–2014, in gigawatt hours. Data: U.S. Energy Information Administration. USGS.

Three goals

USGS gives agencies and industry science-based options to avoid, minimize or mitigate harm:

1. Understand risks — when, where and why wildlife shares space with energy facilities.
2. Measure impacts — direct and indirect effects on species and populations.
3. Inform solutions — technology, management and mitigation.

Understanding risks

It starts with basic biology: a species' range, habitat, diet, migration timing and routes, seasonal behavior, breeding and survival. Tools that track animals over long distances, or monitor them around facilities, reveal which populations are at risk — and the cumulative effects across a species' range or over generations.

Installing equipment to monitor wildlife activity. USGS.

Why bats die at wind turbines

Bats are worth billions of dollars a year to the U.S. — eating crop pests and pollinating desert plants — yet most species remain poorly known. Around the turn of the millennium, unprecedented numbers began dying at wind facilities.

• Who: migratory tree bats, which travel long distances and roost in trees year-round, make up most turbine fatalities in the U.S.
• When: deaths peak during migration and mating, pointing to a seasonal behavior.
• Why: echolocating bats see distant objects mainly by vision, even in dim light. The evidence suggests tree bats may mistake turbines for trees in the dark.
• Fixes being tested: lighting turbines with dim, flickering ultraviolet light only bats can see, so they look less like trees; and high-frequency sound that jams echolocation when bats get dangerously close.

Radar tracks animals moving through the air around energy facilities. USGS.

Measuring impacts

USGS builds tools, methods and datasets so managers, regulators, industry and the public can measure impacts consistently:

• a statistical fatality estimator for wind facilities, widely used;
• a related tool for rare species, being adapted to solar and other facilities.

Rare species: searches may find few or no carcasses — maybe none died, or scavengers took them, or searchers missed them. USGS and the U.S. Fish and Wildlife Service developed an approach ("evidence of absence") that estimates mortality even then, helping show whether permitted take has been exceeded or mitigation is needed. It has aided habitat conservation plans for wind projects, especially in the Midwest.

An evidence-of-absence graph helps operators plan how often, and how much ground, to search for carcasses beneath turbines. USGS.

Informing solutions

• Hydropower: decades of USGS research support fish passage and aquatic-habitat management.
• Wind: turbine curtailment and deterrents, and preconstruction siting tools to keep wildlife out of harm's way; data on migration corridors, habitat and population trends to guide siting.

A golden eagle fitted with a tracking device. USGS.

Forecasting golden eagle deaths

Taking an eagle without a permit is a federal offense under the Bald and Golden Eagle Protection Act. The Fish and Wildlife Service's eagle-permit process gives developers legal and financial certainty in return for conservation benefits. USGS supports it with a pre-construction forecast of golden eagle deaths at proposed wind facilities — since location and topography affect the toll — so regulators and developers can design facilities to minimize it and set compensatory mitigation.

Sources

Based on Renewable Energy and Wildlife Conservation, by Mona Khalil, U.S. Geological Survey Fact Sheet 2016–3067 (DOI; publication page), citing Boyles and others (2011), Cryan and others (2014), Dalthorp and others (2014), Gorresen and others (2015), Huso and others (2012) and New and others (2015). Photographs and graphs restored from the fact sheet's PDF; its hoary bat photograph, © Merlin Tuttle, is left out. A work of the United States government in the public domain.