Page 387 - A Comprehensive Guide to Solar Energy Systems

Chapter 20 • Solar Energy Development and the Biosphere 395

and colleagues [10] found that 42 of the 82 permitting requests for new USSE sites in leece,
2
Italy (238.4 km ) were in ecologically unsuitable areas, comprising 18 563 ha of land-cover
change, including in places with century-old olive groves notable for their cultural value and
that provide the largest contribution to carbon sequestration, relative to other land-cover
types evaluated (>1.5 million tons of CO 2 ).

20.2.3 Surface Grading and Vegetation Removal
During the construction phase of a solar energy power plant, preparation of the facility site
may include grading and scraping, which removes all aboveground biomass [9]. Grading
reduces wildfire risks on-site and prevents the panels from being shaded by vegetation
[10]; however, from an ecological perspective, these activities constitute a loss of habitat
within the footprint of the facility and degradation of surrounding land, which may result
in mortality of wildlife or species displacement. Ecosystems with limited resources (e.g.,
precipitation, nutrients) may be slow to recover from disturbance, either from the con-
struction of the USSE facility itself or its decommissioning, making restoration an inviable
and/or costly option. For example, natural recovery times for desert plant communities
to return to predisturbance species composition is 215 years based on a meta-analysis
of 31 individual studies [10a]. If topsoil has been removed from the site, this recovery
time may be longer and thus restoration potential may be diminished depending on the
size and intensity of the disturbance [11,12]. Additionally, more carbon is sequestered
in soils than in the atmosphere and terrestrial vegetation combined [13]. Therefore, soil
disturbance resulting from site development may release a significant amount of stored
organic (and possibly inorganic) carbon, potentially offsetting benefits of establishing the
renewable energy source (in terms of reducing greenhouse gas emissions). Significant soil
processes are negatively impacted by disturbance, including nutrient cycling and water
holding capacity [14]; soil biota that contribute to these processes, such as biological soil
crusts, may take 20–1000+ years to recover in aridland environments [12], necessitating
costly active restoration techniques that require salvaged material to expedite recovery
[14a]. Disturbed soils are more prone to wind erosion, thus potentially impacting human
health (e.g., valley fever), reducing fertility of biological soil crusts and vegetation through
reduced photosynthesis, and contributing to sedimentation in surface water [15].

20.2.4 Hydrologic Changes and Water Degradation

Construction activities may impact surface-water flow pathways and water quality, espe-
cially when projects are sited on bajadas, individual alluvial fans, floodplains, or near
washes. Flood control structures may be constructed on-site to intentionally divert water
around facility footprints in an effort to reduce soil erosion near facility infrastructure.
Modifications to surface-water flow may alter geomorphological processes and down-
stream aquatic ecosystems and habitats by altering transport of organic matter, nutrients,
minerals, and sediments [16].
large concentrating solar power facilities require large quantities of water for operation,
which may stress water resources, especially in arid environments where water scarcity