Page 393 - A Comprehensive Guide to Solar Energy Systems

Chapter 20 • Solar Energy Development and the Biosphere 401

example, desert plants tolerate high temperatures and solar radiation levels and low pre-
cipitation; however, plants within solar arrays experienced altered microclimates, includ-
ing 11°C cooler temperatures from panel shading and increased water from water runoff at
the edges of panels [59]. These altered conditions may be beneficial to generalist, invasive
annual plant species. Meanwhile, altered microhabitat conditions in solar facilities may
decrease seed production, density, species richness, and community abundance of native
annual species [59]. In aridlands, decreased plant cover and biomass is associated with
decreases in diversity and abundance of small reptiles and other wildlife species [11].

20.3.4 Air-Cooled Condensers and High-Energy Flux
Impacts from air-cooled condensers and high-energy flux are unique to CSP power plants.
Bats may collide with the fans of air-cooled condensers while foraging or in their search to
locate roosting sites, although acoustic deterrents may mitigate this impact. Insects may
collide with fans and are expected to be negatively impacted. Passerines are not expected
to be negatively impacted by air-cooled condensers [60]. More research is needed to better
understand potential effects of air-cooled condensers on wildlife.
Solar flux is created by the high intensity concentration of light reflected off mirrors,
creating temperatures exceeding 800°C. Insects are attracted to the flux field as a source of
polarized light [56,61], resulting in potential incineration of flying insects. Mortality from
solar flux has been documented for both dragonflies and butterflies [55]. Attracted to their
insect food source, insectivorous birds experience singeing of flight feathers when forag-
ing near flux towers, resulting in mortality. Minor singeing causes impairment of flight,
which may lead to inability to forage and evade predators, while severe singeing may
cause loss of flight leading to impact trauma and mortality from collision with mirrors
[54,55,62]. Scavenger species (e.g., corvids, small carnivores) may benefit from bird fatali-
ties at USSE facilities (i.e., from flux and impact; [29]). Bat carcasses have been retrieved
from CSP facilities. While the cause of death remains unknown, bats may be lured into
flux fields while foraging, although neutral effects are expected due to bat activity being
concentrated after sunset. Flux fields and air-cooled condensers are not expected to nega-
tively impact annual or perennial plants, ungulates, small mammals, carnivores, or rep-
tiles, although no research on any of these taxa has been conducted.

20.4 Summary

Globally, solar energy can provide great environmental benefits, not the least of which is
reduced greenhouse gas emissions when substituted for carbon-intensive sources of energy.
Indeed, integrated solar energy and other appropriate siting decisions (e.g., reclamation of
contaminated land) provide additional benefits associated with land sparing. These ben-
efits should be conjunctively considered in contrast to the environmental costs of solar
energy development in places with high biophysical capacity, including natural aridland
environments. Displacive USSE development requires land and, to date, rapid deployment