Home Green Technology Extra Water And Extra Power: The Potential Win-Win Of Floating Photovoltaics

Extra Water And Extra Power: The Potential Win-Win Of Floating Photovoltaics

Extra Water And Extra Power: The Potential Win-Win Of Floating Photovoltaics


Power Innovation companions with the impartial nonprofit Aspen International Change Institute (AGCI) to supply local weather and power 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 current estimate of world reservoir evaporative losses discovered that annual water quantity loss was equal to 70 p.c of all world municipal water withdrawals in 2010. Practically one-third of all reservoirs evaporative losses on this planet happen in Canada and america. Evaporation charges in america are particularly excessive, due partly 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 impression 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 traits for the reason that flip of the millennium. On account of a mixture 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 present. The vertical red line represents the start of the Millennium Drought in 2000. Lake Mead reached peak capacity in 1983; in August 2023, Lake Mead was 33 percent full at 1,061 ft. Data source: Bureau of Reclamation.

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 complete annual circulation is misplaced to evaporation and different system components (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 effectively 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 deal with mitigating evaporative losses. One method 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. In recent times, focus has shifted to shading reservoirs and irrigation infrastructure in dual-purpose supplies comparable to photovoltaics, or PV. Pairing PV with water infrastructure has centered round two strategies: floating PV and PV-covered irrigation canals.

Floating photovoltaics contain the set up of photo voltaic panels on high of froth, buoys, and different buildings that float on the floor of reservoirs, lakes, and ponds. These methods have a tendency to supply power extra effectively than land-based PV, due largely to the cooler temperatures of PV over water our bodies than on land. Because of this, pairing PV with water infrastructure has gained momentum in current many years as a method to lower reservoir evaporation and enhance renewable power 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 know-how is attractive to reservoir operators, energy corporations, and municipalities. Mission areas embrace Alicante, Spain, the place seven p.c of a small irrigation reservoir was coated in floating PV to offset agricultural energy wants; the United Kingdom, the place six p.c of the Queen Elizabeth II reservoir was coated 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 therapy.

These vegetation are comparatively new, so power yields and water financial savings are far beneath their full world potential. Theoretically, masking 30 p.c of the 100,000 reservoirs across the globe with floating PV has the potential to yield 9,434 terawatt-hours yearly, based on a Nature Sustainability article by Yubin Jin and colleagues printed earlier this yr—the equal of roughly 40 p.c of world electrical energy use in 2021. Since reservoirs are sometimes positioned close to communities and metropolitan areas, floating photovoltaics have the potential to supply giant portions of energy near power customers. This co-location technique can lower transportation and line losses, rising the general effectivity of the system. Jin and colleagues estimate that over 150 metropolitan areas might turn into self-sufficient with native floating PV vegetation. Globally, producing power with floating PV on reservoirs might doubtlessly save 106 cubic kilometers of water from evaporative losses every year, a quantity equal to virtually 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 counsel that 10 p.c protection of Lake Mead might yield sufficient water financial savings and energy manufacturing for Las Vegas and Reno mixed.

Whereas the sunny Southwest is sluggish 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 research by Brandi McKuin and colleagues that highlighted potential water financial savings and power 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 undertaking deploying PV over its irrigation canals this fall. The Turlock Irrigation undertaking is a partnership between the irrigation district, a non-public photo voltaic firm (Photo voltaic AquaGrid), the California Division of Water Assets, and a analysis group on the College of California, Merced. In an analogous vein, the Gila River Indian Group in central Arizona acquired 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 way from sated. A letter to the Secretary of the Inside in July, 2023, from quite a lot 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 very large, the know-how stays comparatively unproven. Environmental issues embrace steel leaching, ecosystem impairment, and decreased gentle depth in aquatic ecosystems underneath the installations. Outcomes from a pilot research on Oostvoornse Lake within the Netherlands present that floating photovoltaics scale back gentle depth by 70 to one hundred pc underneath 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 increased set up prices and lift extra upkeep issues than land-based photo voltaic.

Regardless of these challenges, pairing PV and water infrastructure has huge 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 method to water administration, with huge potential for growth. As reservoir evaporation continues to squander giant portions of water in arid areas worldwide, it’s time to maintain the momentum shifting ahead towards next-generation sustainable options on the water-energy nexus.


Featured Analysis
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