Vitality Innovation companions with the impartial nonprofit Aspen International Change Institute (AGCI) to supply local weather and vitality analysis updates. The analysis synopsis beneath comes from AGCI’s Tanya Petach. A full listing of AGCI’s updates is out there on-line.
Aerial view of floating photovoltaic panels on a lake. Picture credit score: Photo voltaic AquaGrid
In arid river basins across the globe, substantial water provide is misplaced via evaporation. A latest estimate of world reservoir evaporative losses discovered that annual water quantity loss was equal to 70 p.c of all international municipal water withdrawals in 2010. Almost one-third of all reservoirs evaporative losses on the planet happen in Canada and america. Evaporation charges in america are particularly excessive, due partially to the truth that the 2 largest U.S. reservoirs (Lake Powell and Lake Mead) are positioned within the scorching, dry deserts of the Southwest. And evaporation doesn’t simply influence reservoirs—it additionally desiccates irrigation canals, ditches, and holding ponds.
Lake Powell and Lake Mead, each on the Colorado River, have skilled long-term drying tendencies because the flip of the millennium. Because of a mix of extended drought, water overuse, and warming temperatures, these reservoirs misplaced 61 p.c of their full storage quantity from January 2000 to April 2023. Whereas this yr’s hefty Rocky Mountain snowpack helped alleviate the impacts of the final 23 years of drought, one good snow yr isn’t sufficient to bail the Colorado River out of long-term drought.
Lake Mead water elevation from 1970 to current. The vertical pink line represents the beginning of the Millennium Drought in 2000. Lake Mead reached peak capability in 1983; in August 2023, Lake Mead was 33 p.c full at 1,061 ft. Knowledge supply: Bureau of Reclamation.
As water availability decreases within the Colorado River Basin, water use is extra extremely scrutinized. Alongside municipal, agricultural, and industrial customers, evaporation is a stealth water shopper. The Southern Nevada Water Authority not too long ago estimated that roughly 12 p.c of the Colorado River’s whole annual circulate is misplaced to evaporation and different system parts (e.g., infiltration into ditch banks). In a water-stressed basin the place the federal authorities pays billions of {dollars} for modest water financial savings, 12 p.c loss provides as much as quite a lot of water. Presently, these losses aren’t nicely accounted for within the Decrease Colorado River, however some specialists are urging policymakers to just do that.
Whereas reservoir evaporation contributes to water shortage within the Colorado River and different arid river basins, water managers are starting to give attention to mitigating evaporative losses. One strategy to attenuating this loss is to cowl reservoirs and irrigation ditches in shading supplies such because the 96 million “shade balls” that have been deployed in 2015 to shade Los Angeles Reservoir in California. Lately, focus has shifted to shading reservoirs and irrigation infrastructure in dual-purpose supplies similar to photovoltaics, or PV. Pairing PV with water infrastructure has centered round two methods: floating PV and PV-covered irrigation canals.
Floating photovoltaics contain the set up of photo voltaic panels on prime of froth, buoys, and different constructions that float on the floor of reservoirs, lakes, and ponds. These methods have a tendency to provide vitality extra effectively than land-based PV, due largely to the cooler temperatures of PV over water our bodies than on land. Consequently, pairing PV with water infrastructure has gained momentum in latest a long time as a way to lower reservoir evaporation and improve renewable vitality manufacturing.
Floating photovoltaics are thriving in Asia, which hosts 97 p.c of worldwide put in floating PV, primarily in China, Japan, and Korea. This win-win expertise is engaging to reservoir operators, energy corporations, and municipalities. Venture places embrace Alicante, Spain, the place seven p.c of a small irrigation reservoir was lined in floating PV to offset agricultural energy wants; the United Kingdom, the place six p.c of the Queen Elizabeth II reservoir was lined in floating PV for municipal energy technology; and Colorado, the place the city of Walden is utilizing floating PV to offset energy necessities for water remedy.
These vegetation are comparatively new, so vitality yields and water financial savings are far beneath their full international potential. Theoretically, protecting 30 p.c of the 100,000 reservoirs across the globe with floating PV has the potential to yield 9,434 terawatt-hours yearly, in accordance with a Nature Sustainability article by Yubin Jin and colleagues printed earlier this yr—the equal of roughly 40 p.c of international electrical energy use in 2021. Since reservoirs are sometimes positioned close to communities and metropolitan areas, floating photovoltaics have the potential to provide massive portions of energy near vitality customers. This co-location technique can lower transportation and line losses, growing the general effectivity of the system. Jin and colleagues estimate that over 150 metropolitan areas may change into self-sufficient with native floating PV vegetation. Globally, producing vitality with floating PV on reservoirs may doubtlessly save 106 cubic kilometers of water from evaporative losses annually, a quantity equal to nearly 25 p.c of annual family water use in america.
The 2 main reservoirs within the Decrease Colorado River stay a part of this theoretical future yield. Neither Lake Powell nor Lake Mead has but tapped into floating PV to curb reservoir evaporation—although research recommend that 10 p.c protection of Lake Mead may yield sufficient water financial savings and energy manufacturing for Las Vegas and Reno mixed.
Whereas the sunny Southwest is gradual to undertake floating PV on reservoirs, there’s a wholesome urge for food for PV-covered irrigation canals. Impressed by a College of California, Merced examine by Brandi McKuin and colleagues that highlighted potential water financial savings and vitality manufacturing from PV-covered irrigation canals within the area, the Turlock Irrigation District in California’s Central Valley is poised to interrupt floor on a venture deploying PV over its irrigation canals this fall. The Turlock Irrigation venture is a partnership between the irrigation district, a personal photo voltaic firm (Photo voltaic AquaGrid), the California Division of Water Assets, and a analysis group on the College of California, Merced. In an identical vein, the Gila River Indian Group in central Arizona obtained funding this yr from the Bureau of Reclamation for water conservation infrastructure, together with PV-covered ditches and canals. And the urge for food for PV-covered irrigation infrastructure is much from sated. A letter to the Secretary of the Inside in July, 2023, from a wide range of advocacy organizations, requested pressing motion to deploy extra photovoltaics over irrigation canals.
Rendering of future photovoltaic-covered canal within the Turlock Irrigation District, California. (Picture Supply: Photo voltaic AquaGrid)
Whereas the potential from floating PV on reservoirs and PV-covered canals is huge, the expertise stays comparatively unproven. Environmental considerations embrace metallic leaching, ecosystem impairment, and decreased mild depth in aquatic ecosystems beneath the installations. Outcomes from a pilot examine on Oostvoornse Lake within the Netherlands present that floating photovoltaics scale back mild depth by 70 to one hundred pc beneath installations, with potential cascading impacts on lake ecosystems. But researchers word that conventional PV installations additionally trigger appreciable environmental impacts, and direct comparisons are complicated. Along with environmental dangers, floating photovoltaics have larger set up prices and lift extra upkeep considerations than land-based photo voltaic.
Regardless of these challenges, pairing PV and water infrastructure has monumental potential to assist re-stabilize water provides within the Colorado River and different drought-stricken areas across the planet. Within the arid Southwest, intensified scrutiny on evaporative losses, requests for elevated federal curiosity for paired water infrastructure-PV methods, and daring exemplar tasks just like the PV-covered canal methods within the Turlock Irrigation District and Gila River Indian Group are ushering in a brand new strategy to water administration, with large potential for growth. As reservoir evaporation continues to squander massive portions of water in arid areas worldwide, it’s time to maintain the momentum transferring ahead towards next-generation sustainable options on the water-energy nexus.
