In 2019, floating solar technology has been gaining traction as a cost-effective alternative to ground- and rooftop-mounted photovoltaic systems, largely driven by falling PV module prices and challenges to dedicating large plots of land to solar development.
“Going solar,” regardless of where the panels are mounted, already offers tremendous financial and environmental benefits to people and organizations who make the switch—but floating PV panels on water is uniquely suited to play nicely with local ecosystems.
Let’s take a look at how floating solar not only provides a resource for clean, renewable energy, but can also help local environments.
Floating solar panels on water is gentler to the ground—obviously—but the environmental benefits can be surprising. If a ground-mounted solar array involves 100 ground disturbances, primarily in the form of foundations dug and poured for racking equipment, a floating solar array of the same production capacity would involve roughly 8 disturbances. These show up primarily at mooring sites where the floats are anchored.
This matters to biodiversity and topsoil health. Although a solar power plant has major advantages over coal-fired plants in terms of air quality, greenhouse gas emissions, and mining and waste byproducts, a 30-year-old ground-mount array still only disturbs 15% less land than a coal plant of equivalent capacity—because while a solar plant doesn’t have to mine for fuel, it still takes up a lot of space.
While solar arrays are often deployed on distressed or previously contaminated lands, such as burned-out cropland that probably should have never been harvested in the first place, other large arrays built to achieve energy cost savings involve clear-cutting and deforestation to make room for panels. This feels like an example of losing the forest for the tr—let’s just call it counterproductive.
Ground disturbances have several impacts on the health of an ecosystem. There’s the direct destruction of habitat due to excavation, which also destroys topsoil and root networks. Compacting land can also eliminate animal migration and routes for hunting and grazing. Combined, the result is a reduction in local biodiversity, and while the quantifiable relationship between biodiversity and overall ecosystem health is still a matter of contention among scientists, it’s generally accepted as a powerful indicator of whether an ecosystem is thriving or suffering. Disturb less land, threaten less biodiversity, maintain healthy ecosystems.
Even the installation is easier on the land. By eliminating the need for heavy construction equipment, floating solar installations are less likely to contribution to soil compaction, which would otherwise hinder water’s ability to infiltrate into the soil, leading to worsened runoff and flooding.
As mentioned earlier, floating solar removes the need for heavy construction. Panels are transported to the installation site, assembled on shore, and pushed into the water row by row. From an installation standpoint, this reduces environmental impacts in several ways.
Anybody who’s endured an EIR project under CEQA (I have) knows that projects are held accountable for construction phases as well as the final impact of a completed, operating project. Floating solar beats ground-mounted solar in nearly all of these areas. The lack of heavy machinery means less soil compaction, again, but also reduces the likelihood of creating traffic, diesel emissions, noise pollution, and oil spills.
Minimal construction also means less light pollution at night, and eliminates the liability caused by having portable toilets on site for installation crews. All told the installation is much less invasive to the surroundings.
Outside of the direct environmental impacts of heavy construction like local emissions, construction creates waste. This is inevitable when you’re replacing volumes of earth with foundations and racking equipment, excavating, and dealing with concrete and asphalt. Floating solar eliminates nearly all construction waste from installations, which means we’re helping take pressuring off the looming global landfill crisis.
Of course, solar panels themselves create waste, and this is unavoidable no matter where your array is mounted. We won’t pretend this issue doesn’t exist, but we’re encouraged by growing efforts to manage photovoltaics recycling on a global scale, and we view the waste as a manageable cost of rapidly moving our planet away from fossil fuels.
Impacts to Water Quality
Excavating land also impacts water quality by introducing new particulate into waterways and increasing turbidity. Turbidity, or cloudy water, can directly harm fish health, hurt their food supply, hinder egg and larvae development, and modify migration paths. Turbidity also creates problems in waterways designated for human use. Though floating solar installation can create tiny amounts of turbidity at anchoring sites, the potential for harm is minimal relative to tearing up acres of land to install ground-mounted solar.
Outside of turbidity, floating solar also provides a platform for mitigating harmful algal blooms (HABs). This is a benefit that’s likely to come up in a large part of our writing into perpetuity. HABs are a growing problem in the United States, largely driven by warmer temperatures and increasing levels of nitrates and phosphates in agricultural runoff. HABs cause issues when their biomass accumulates and denies sunlight to deeper parts of water bodies, but the algae themselves often produce toxic byproducts, which can be devastating to ecosystems and economies alike. Impacts to humans range from simply smelling awful, to serious respiratory complications that can even be fatal. Whether you’ve had a weekend of swimming ruined at your favorite lake in SoCal, or you’re counting your blessings in Florida as the terrifying “red tide” crisis seems to be passing, chances are you’re only a degree of separation from being impacted by HABs.
According to a fantastic recent NREL study, floating solar can help mitigate algae growth in water bodies. This is largely due to the benefit provided by shading water surfaces, but floating solar can also assist with more aggressive mitigation strategies. Floating solar arrays can also serve as a good mounting spot for ultrasound, aeration, and circulation equipment, that’s shown to help with algal blooms, and can help offset the cost of powering that gear as well.
Ultimately HABs will be a problem as long as we use nitrates and phosphates in agriculture, which isn’t likely to change any time soon, as much as we’d like to fantasize about a world of purely organic farms. Floating solar can still act as a helpful mitigation strategy while farmers look to other preventive measures, such as switching from sprinklers and flooding to drip irrigation, finding viable alternatives to nitrate-based fertilizers, or deciding to take the plunge and transition to organic farming.
Impacts to Water Supply
Drought is likely to be a fact of life in the Southwestern United States for the rest of our lives. It’s even becoming a problem in the Pacific Northwest. It’s impossible to dig into water scarcity for long before facing the question of evaporation.
Evaporation is a massive issue for appropriative water infrastructure. Even four decades ago, water managers were aware that evaporation accounts for up to 13% of losses on the Colorado River (that’s 1.5 million acre-feet per year, or 2.4 times what the City of Los Angeles uses annually). If you want an even more mind-numbing statistic to help you grasp the impact that evaporation has on our society, the University of California at Irvine released a study estimating that evaporation from irrigation in California’s Central Valley sends enough water vapor to the Colorado River Basin to serve the needs of 3 million people annually. The sociopolitical implications of this report are staggering—hopefully this drives the point home that evaporation matters in the United States.
Floating a solar array over a body of water will reduce evaporation. This is due to shielding the water from solar irradiance, reducing temperatures in the water, and protecting the water’s surface from wind. Just how much is a complicated question (embattled floating solar developer Pristine Sun claimed a reduction of up to 90% in a patent filing, which we feel is…ambitious), but depending where you fall on the Cooley vs Linacre debate, floating solar could conservatively reduce 30% of evaporation on shaded areas, depending on several variables such as dew point and wind speed.
Retaining more water supply can have massive environmental implications, depending on the situation. If farmers aren’t receiving their allotted water deliveries, they could end up having to fallow cropland, which often leads to devastating air quality hazards downwind. Even worse, they could turn to less sustainable or more poorly-managed sources of water, such as this county in Arizona that has decided to continue pumping their local aquifer, absent of Colorado River deliveries, until…until…well, we’d like to think they’ll come up with an alternative before it’s too late. Groundwater overdraft can lead to land subsidence, permanently reducing an aquifer’s storage capacity, and can cause lakes and streams to literally run dry, threatening hosts of species with extinction.
In general, if humans are scrounging around for new water, it will likely spell Very Bad News for members of the affected ecosystem. Just ask the Delta smelt. By reducing evaporation, floating solar reduces the need for supplemental water supply and its significant opportunity cost.
If the choice is between ground-mounted solar and fossil fuel combustion, we pick solar. But if you’re facing a choice between installing ground-mounted solar and floating panels on the water, floating solar will provide you—and our shared ecosystem—with significant environmental benefits.
Ready to start your solar project? If your organization has non-recreational surface water on site and you want to find out how much you’ll save with a floating solar system, visit our website or give us a call today at (800) 445-2565.