Land-Sparing Opportunities for Solar Energy Development in Agricultural Landscapes: A Case Study of the Great Central Valley, CA, United States

Abstract

Land-cover change from energy development, including solar energy, presents trade-offs for land used for the production of food and the conservation of ecosystems. Solar energy plays a critical role in contributing to the alternative energy mix to mitigate climate change and meet policy milestones; however, the extent that solar energy development on nonconventional surfaces can mitigate land scarcity is understudied. Here, we evaluate the land sparing potential of solar energy development across four nonconventional land-cover types: the built environment, salt-affected land, contaminated land, and water reservoirs (as floatovoltaics), within the Great Central Valley (CV, CA), a globally significant agricultural region where land for food production, urban development, and conservation collide. Furthermore, we calculate the technical potential (TWh year–1) of these land sparing sites and test the degree to which projected electricity needs for the state of California can be met therein. In total, the CV encompasses 15% of CA, 8415 km2 of which was identified as potentially land-sparing for solar energy development. These areas comprise a capacity-based energy potential of at least 17 348 TWh year–1 for photovoltaic (PV) and 2213 TWh year–1 for concentrating solar power (CSP). Accounting for technology efficiencies, this exceeds California’s 2025 projected electricity demands up to 13 and 2 times for PV and CSP, respectively. Our study underscores the potential of strategic renewable energy siting to mitigate environmental trade-offs typically coupled with energy sprawl in agricultural landscapes.

Mutually-Beneficial Renewable Energy Systems

“…Common mitigation measures for solar energy include selecting areas of low conservation value and implementing biodiversity-friendly Relations -6.1 -June 2018 http://www.ledonline.it/Relations/ operating procedures (Gasparatos et al 2017). Mutually-beneficial opportunities for solar energy broadly involve flexible siting options, supporting use of degraded lands and water bodies, co-location with other uses and technologies, restoration of ecosystem functions and habitats within and adjacent to installations, and integration within built environments (Stoms, Dashiell, and Davis 2013;Hernandez et al 2014;Hoffacker, Allen, and Hernandez 2017;Moore-O'Leary et al 2017).…”

“…Conversion of degraded lands may include converting cultivated lands to prairies and meadows, or making use of brownfields, abandoned mining lands, salt-contaminated lands, or existing transportation and transmission corridors (BirdLife Europe 2011; Northmore 2014; Hernandez et al 2015;Hoffacker, Allen, and Hernandez 2017;UCS 2017). Integration within built environments can take increasingly diverse forms, from common rooftop solar systems (Moore-O'Leary et al 2017; UCS 2017) to building-integrated PV (Cannavale et al 2017;Moore-O'Leary et al 2017;Jakica 2018), green roofs (Gasparatos et al 2017), clear window modules (Hoffacker, Allen, and Hernandez 2017), various construction components (Uyterlinde et al 2017), noise barriers (Hoffacker, Allen, and Hernandez 2017), solar road panels (Northmore 2014), and solar PV sculptures and solar trees for public art and education (Ferry, Monoian, and Koh 2012;Hyder, Sudhakar, and Mamat 2018).…”

“…During site preparation, practices include conserving original vegetation (Macknick, Beatty, and Hill 2013) and installing arrays without grading (Beatty et al 2017). During operations, solar energy accommodates native vegetation under and around panels; modified height and spacing of PV panels to allow rough pasture, prairie, meadow and grassland habitats to flourish; pollinator-friendly habitat and planting of wild bird seed, nectar mixes or cover crops between rows; nest boxes and roosting, perching and hibernating structures within control buildings; wildlife-friendly hedges for fencing; and management for nutrient cycling and erosion control (BirdLife Europe 2011; Macknick, Beatty, and Hill 2013;Montag, Parker, and Clarkson 2016;Beatty et al 2017;Benage 2017;Hoffacker, Allen, and Hernandez 2017;Moore-O'Leary et al 2017). Solar energy may support restoration of wetland habitats in former agricultural and industrial areas through purification of groundwater (Pevzner 2015).…”

“…Agrivoltaics also make use of farm structures including greenhouses and barns, underutilized spaces such as distribution areas and parking lots, and agriculture lands of lower soil quality (Macknick, Beatty, and Hill 2013;Hernandez et al 2014;Hagen and DePillis 2017;Moore-O'Leary et al 2017). For floatovoltaics, floating arrays deployed in reservoirs, dam impoundments, irrigation canals, lakes, ponds, and former mining pits adapt to changing water levels while improving panel conversion efficiency and reducing evaporation (Hernandez et al 2014;Hanley 2017;Hoffacker, Allen, and Hernandez 2017;Moore-O'Leary et al 2017). When combined with aquaculture (aquavoltaics), floating PV systems support food production, provide artificial fish habitat and oxygenate surface waters (Pringle, Handler, and Pearce 2017).…”

“…Integration can smooth daily or seasonal variability, provide additional functions such as water conservation and food production, and reduce overall area required. Similarly, co-locating battery and pumped hydropower storage supports optimization of variable energy technologies, extends facility lifespans, reduces land area, and makes use of degraded sites in proximity to new or existing installations (Pevzner 2015;Hoffacker, Allen, and Hernandez 2017;Immendoerfer et al 2017). Transmission systems provide opportunities beyond conventional mitigation strategies (e.g., buried lines, insulated cables, single-level arrangements (BirdLife Europe 2011; UNEP 2016), such as restoring landscapes beneath and around power lines, integrating habitat and perching, roosting and nesting sites for bird species not at risk of collision, and co-locating solar PV (BirdLife Europe 2011; Uyterlinde et al 2017).…”