Renewable Energy

By NABCANABCA, on 17 Mar 2017 05:46

Threat Description

The impacts of exploring, developing, and producing renewable energy (solar, wind, geothermal, and tidal power but not hydropower) on roosting and foraging habitat, as well as direct mortality of bats. Potential impacts include, mortality due to collision with wind turbines or barotrauma, habitat loss due to conversion of land for infrastructure footprint, negative impact of reflective surfaces on foraging ecology of bats (turbine monopoles and solar panels) and water degradation and pollution due to geothermal ponds.

Perceived Importance of this Threat

The apparent importance of this threat

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Mitigation Measures

The USGS has developed some general information on addressing impacts of renewable energy on wildlife conservation:

USGS Renewable Energy and Wildlife Conservation Fact Sheet (Kahlil 2016)
USGS Energy and Wildlife Annual Report for 2016 (Kahlil 2016)

Wind

There has been considerable research showing that wind turbines can lead to substantial mortality of many species of bats. Recent reviews of impacts in North America include "Comparing bird and bat fatality-rate estimates among North American wind-energy projects" (Smallwood 2013), "Bats Killed in Large Numbers at United States Wind Energy Facilities" (Hayes 2013) and "Bat mortality due to wind turbines in Canada" (Zimmerling and Francis 2016), while "Impacts of wind energy development on bats: a global perspective" (Arnett et al. (2016) reviews impacts on a global scale.

Within North America, the species that have been killed most frequently are the migratory tree-roosting bats, including Hoary Bat (Lasiurus cinereus), Red Bat (Lasiurus borealis) and Silver-haired Bat (Lasionycteris noctivagans), but many other species are also sometimes killed. In some areas, substantial numbers of Little Brown Bats (Myotis lucifugus) have also been killed.

The population level impacts of this mortality are less certain. A recent paper by Frick et al. (2017), suggests that mortality of Hoary Bats (Lasiurus cinereus) at wind turbines, at the continental scale in North America, may be sufficient to threaten their population viability. Furthermore, for species such as Myotis spp. that are already severely impacted by other threats such as White-Nose Syndrome, even small amounts of mortality could reduce the likelihood of recovery of populations.

Several potential mitigation measures have been proposed to reduce the impacts of wind turbines on bat populations.

Siting: The most effective approach to avoid mortality of bats, is not installing wind turbines in areas where there are large numbers of bats. Unfortunately, relatively little is known about the migratory pathways of bats. Many of the migratory tree bats appear to be killed during southward migration in autumn, but it is not known whether they are concentrated in limited migration corridors, or traveling broadly across the landscape. One or more seasons of pre-construction acoustic monitoring at proposed turbine sites could be used to monitor bat activity, but there are no studies currently available showing a convincing relationship between pre-construction bat activity and post-construction mortality (Lintott et al. 2016).

Selective Shut Downs: The most effective approach for reducing mortality is to prevent the blades from spinning at night during periods of high bat activity. However, given that bats can potentially be active for several months per year, this would result in substantial loss of power.

Several studies have shown that limiting blades from turning during low and intermediate wind speeds (e.g., <5.5 m / second) can reduce fatalities by 44-93% with relatively little loss of power (Arnett et al. 2011). It is important to ensure that turbine blades are feathered to prevent them from spinning (or to keep them spinning at less than 2 revolutions per minute); shutting down power production without stopping the blades from spinning is not sufficient to reduce the risk of mortality.

An alternative approach that appears to be very effective is to use Acoustic Sensors that detect bat activity around the turbines. When the activity exceeds a predetermined threshold, the blades are automatically feathered. One study by Normandeau Associates that their Turbine Integrated Mortality Reduction (TIMR) system resulted in decreased bat mortality rates from turbines by up to 90%. Because power generation is only stopped during periods when bats are actually known to be present, this reduces the period with loss of power relative to other approaches that are based on more predictive mortality. Further research is needed to determine how effective this will be in other areas.

Deterrents: Ongoing research is looking at the possible effectiveness of deterrents, including ultrasonic deterrents. However, data are not yet available on their effectiveness.

Industry-wide adoption of some of these measures could substantially reduce mortality for some species of bats.

Further information and ongoing research on this topic can be found at the Bats and Wind Energy Cooperative (BWEC). This is an alliance of experts from government agencies, private industry, academic institutions, and non-governmental organizations that cooperate to develop and disseminate solutions to reduce to the greatest extent practicable or, where possible, prevent mortality of bats at wind energy facilities.

Solar

The development of utility-scale solar energy development (USSED) projects and associated construction of new substations, transmission lines, and access roads has the potential to negatively impact wildlife movement.
To prepare an area for a new USSED facility, land is cleared of vegetation, and graded (if necessary) to have minimal slope. The loss, degradation and fragmentation of habitat that results from a solar energy facility are the primary concerns when considering impacts to bats and other wildlife in the area.

USSED facilities generally have large impervious surface areas which block or reroute surface flows and may use significant amounts of groundwater (if using water-cooled systems for turbines). The resulting changes in drainage patterns, storm water runoff, and groundwater use are important considerations when determining potential impacts to bat populations.

Additional research is needed to determine the effects of this technology on flying animals (Diehl et al 2016). Because of their tendency to forage close to the ground, pallid bats (Antrozous pallidus), may be impacted by solar facilities.

Known and suspected impacts to wildlife from facility construction and operation include habitat fragmentation, road mortality, electromagnetic field effects, changes to local and regional climates, pollution, water consumption, and fire (Lovich and Ennen 2011).

Potential mitigation measures include:

Avoid using or degrading large, intact habitat areas; use disturbed areas or agriculture lands with low habitat value when possible.

Avoid high quality wildlife habitat when disturbed areas are not an option.

Areas that are temporarily disturbed during construction (e.g., roads, staging areas) should be returned to the original grade and revegetated with site appropriate native species following construction.

Use existing roads for construction and access when possible.

Be prepared to prevent and manage noxious or invasive plants during the life of the project.

Sustainability of utility-scale solar energy - critical ecological concepts

Geothermal

Tidal Power

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Challenges/Barriers to Addressing this Threat

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