Giles Exley, Lancaster University
Solar power is now the cheapest source of electricity in history, according to a 2020 report by the International Energy Agency. But there’s something holding this clean energy powerhouse back: space. Unlike fossil fuel power stations, solar farms need a lot of room to generate enough electricity to keep up with demand. Most solar farms are composed of ground-mounted panels that take up land that could be used to grow food or provide habitat for wildlife.
Although electricity and water don’t usually mix, a growing number of floating solar farms are being deployed worldwide. Floating solar panels on a lake or reservoir might sound like an accident waiting to happen, but recent studies have shown the technology generates more electricity compared with rooftop or ground-mounted solar installations. This is thanks to the cooling effect of the water beneath the panels, which can boost how efficiently these systems generate electricity by as much as 12.5%.
That said, lakes and reservoirs are already very important for people and the planet. While these freshwater bodies cover less than 1% of Earth’s surface, they nurture almost 6% of its biodiversity and provide drinking water and crop irrigation that’s vital to billions of people. Worryingly, climate change has raised the surface temperatures of lakes globally by an average of 0.34°C per decade since 1985, encouraging toxic algal blooms, lowering water levels and preventing water mixing between the distinct layers which naturally form in larger and deeper lakes, starving the depths of oxygen.
In the rush to decarbonise energy in order to slow global warming, might turning to floating solar farms simply add to the strain on the world’s precious freshwater reserves? Remarkably, in new research, we found that carefully designed floating solar farms could actually reduce the threats posed by climate change to lakes and reservoirs.
A buffer against warming
Along with colleagues, I used a computer model to simulate how floating solar farms are likely to affect lake water temperatures. Our simulations are based on Windermere, the largest lake in England and one of the most well-studied lakes in the world.
Floating solar farms reduce how much wind and sunlight reaches the lake’s surface, changing many of the processes that occur within. As each floating solar farm has a different design, we ran simulations to see how lake temperatures changed with over 10,000 unique combinations of wind speed and solar radiation.
Our results suggest that the changes to water temperatures caused by floating solar farms could be as big as climate change itself, only in the opposite direction.
A floating solar farm that reduces wind speed and solar radiation by 10% across the entire lake could offset a decade of warming from climate change. Designs that shaded the lake more than sheltered it, by reducing sunlight more than wind, had the greatest cooling effect. Evaporation fell and the lake was mixed more frequently, which helps oxygenate the deeper water.
These effects might vary depending on a lake’s depth, surface area and location. But ecological processes in lakes are most affected by wind speed and sunlight, which is what our simulations focused on.
Global potential
While most of our simulations indicated a win-win for lakes and floating solar farms, some suggested undesirable side effects. In a small number of simulations, we found that floating solar farms that reduced wind speed at the lake’s surface more than they reduced sunlight might actually mimic or amplify the effects of climate change, increasing how long deeper lakes remain stratified. Thankfully, we think the careful design of floating solar farms should reduce these risks.
Floating solar power has grown more than a hundredfold in the past five years, reaching 2.6 gigawatts of installed capacity across 35 countries. If just 1% of the surface area of all human-made water bodies (which are easier to access and typically less ecologically sensitive than natural lakes) was covered by floating solar panels, it could generate 400 gigawatts – enough electricity to power 44 billion LED light bulbs for a year.
Floating solar is likely to make an important contribution to the decarbonisation of the world’s energy supplies. In a stroke of serendipity, our research suggests this could have the added benefit of offsetting part of the damage to lakes caused by rising temperatures.
Still, our simulations only covered the physical effects of floating solar, while other questions remain unresolved. How would floating solar farms interact with other lake uses, such as sport or aquaculture? How would the wildlife sharing the lake fare? And which lakes are best suited to hosting a floating solar farm? The work to fully understand the potential of this technology is only just beginning.
Giles Exley, Associate Lecturer of Energy and Environment, Lancaster University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
“Worryingly, climate change has raised the surface temperatures of lakes globally by an average of 0.34°C per decade since 1985, encouraging toxic algal blooms, lowering water levels and preventing water mixing between the distinct layers which naturally form in larger and deeper lakes, starving the depths of oxygen.”
This idiot must not have heard of the Great Lakes where the water has been at record levels the past few years. I was at a few places on Lake Michigan where the parking lots were underwater and you had to swim out to the dock to get to your boat.
Someone please explain how climate change adversely affects lakes?
Ssshhhh. They have a solution. Who cares what the problem is. /sarc
They model floating solar plants. This is something that would be easy to verify with a pilot project. I remember that “researchers” were surprised that an average temperature in a solar plant in Arizona was higher than in a field next to it.
100% wrong. Solar panels emit heat to the back of the panel. Evaporation reduces water temperature, but requires free flow of air, rather than a reduction of wind speed on the surface. Plankton and algae absorb CO2, “capturing” carbon from the atmosphere and water, and releasing oxygen. This model must represent solar panels as shade only, not as an active system that absorbs and emits heat, and requires substantial maintenance and cleaning — even more so in a marine environment than on land. The cost of recovery and retirement must also be greater. I don’t know the qualifications for a lecturer of Energy and Environment, but I suspect that technical engineering expertise is not part of it.
Accident waiting to happen. I aggree with that.
I live in Western Canada at 4,000 ft. above sea level. Do they have ice-friendly panels? Can you put an ice-fishing shack on them?
Giles Giles Giels oh where would one even start
In much of the world floating solar would hide the garbage and sewage or exist alongside.
These ‘scientists’ really are incredible.
The only seem to see an existential threat from a slight increase in the concentration of a life-giving trace gas, but when it comes to doing some actual destruction to the environment (e.g. blotting out the sun FFS!) they’re all gung-ho.
They’re just shills for BigWind and Solar, the Subsidy Miners. Like with all the wind farms being decommissioned in Germany recently, because the subsidies ended. So much for green power being affordable. Lots of ‘good’ green jobs slicing up dangerous fiber glass blades and filling up landfills.
Aquatic plants (removes CO2, releases O2) across the lake & shade from trees etc near the shore line would be better for the lake, fish, insects & birds than floating solar panels.
The stupid, it burns.
Yes. Ludicrous.
Go for it …in the Finger Lakes and Lake Michigan next to Chicago. In New Orleans they would shoot at them like they do the Super Dome.
On Windermere, less shooting but the many motorboats would chew through the panels. The boating crowd on the lake have no intention of moving and see no reason whatsoever to change.
And on the shoreline beside, an electrical facility burning wood pellets. Nirvana.
Yes, at Loch Ness and don’t forget the fins.
What happens to a floating array of solar panels when strong winds whip up waves on a lake, and water splashes over the top of the solar panels? Would some of this water leave algae or underwater plants behind when it evaporates? Could a floating array of solar panels break loose from its anchors, drift across a lake, and be bashed against the downwind shore by wind and waves?
What happens if a wave washes over the connection between the solar panels and the wires to transmit the electric power to land? Does it cause a short circuit?
What about when the surface of a lake freezes in the winter? On many lakes, expanding ice floes can form heaves (rising ice) when they meet. Could expanding ice crush a floating solar panel? Could snow accumulate on a flat floating solar panel, without sliding off as it would from a sloping solar panel on a roof?
Most solar panels mounted on roofs are tilted to face south, in order to maximize sun angle in the winter. A floating solar panel will always be flat (or temporarily tilted in random directions by waves), so the incident solar angle in winter will be much lower than for a solar panel mounted on a south-facing roof.
Lots of problems to be solved, but let’s see what floats their boat.
Alrighty then, the answer is to use sterile bodies of water to float these solar arrays.
That means covering pumped hydro reservoirs with the floating panels.
Not that there’s many of those available…
But it’s a double-win-win!
I too was thinking of a twofer…make these floating solar panels part of a wave generator, so as the waves lift and drop the solar panels, you get solar PV and wave power. Both pretty much useless for grid scale generation.
What if there is no temperature change due to climate change because there is no actual climate change.
Water saturated with air has 9.1 mg/Lt. of dissolved O2 (oxygen), when the temperature is 20*Celsius (figure 7-10 mg O2 / Lt depending on solubilized ionic compounds, temperature & partial pressure of the oxygen). At the temperature range of 20-23*Celsius micro-organisms consume 0.3-0,4 mg/Lt. of dissolved O2.
Plants that encounter declining O2 respond by increasing synthesis of a precursor molecule (ACC) that can be used to make the plant hormone ethylene (CH2=CH2). The original post’s implication is that floating hydroponic structures will segregate the water underneath from 02 in the air above. O2 oxygen transfers from it’s gas phase to liquid via a gas-liquid interface & on either side of this interface is a layer of stagnation the oxygen must penetrate, become dissolved at the interface & subsequently move through a stagnant liquid film layer into the bulk body of water.
There is a non-linear response to consider. Namely, that although there is more of the ethylene precursor (ACC) as O2 falls (ex: paper bagging avocados restricts O2, so ethylene ripens them faster) it is none-the-less O2 itself which is needed for the conversion of that precursor to ethylene.
All plant tissue has ethylene dynamics. Our common land di-cotyledon plants’ green shoot growth is lessened when ethylene levels are elevated. However, hydro-phytes & rice growth is greater when ethylene levels are elevated. Which is to say that should floating hydroponic stations reduce the dissolved oxygen too low then aquatic plants will waste energy synthesizing a precursor that it can’t fully exploit hormonally.
As for micro-organisms these too require the hormone ethylene. In dividing cells the level is about 1.22 micro-Mole ethylene / hour / gram dry weight of the cell; which peaks as the cells’ growth hits the “stationary” phase (when cell no longer has any change in mass; slowed growth is balanced with cell death). Which, I propose, means that the preceding “deceleration” phase of growth (when the growth rate decreases from phase of cells expanding & dividing) will occur earlier under the floating hydroponic installation.
From the lead sentence of the above article:
“Solar power is now the cheapest source of electricity in history, according to a 2020 report by the International Energy Agency.”
I cannot believe that is true on a levelized cost of electricity (LCOE) accounting basis, which takes into account things such as the amortized cost of the land, infrastructure, maintenance, etc, over the lifespan of the given power source. I base this conclusion of the very low power generation rate per m^2 of PV panels and the very low utilization rate for PV panels considering average fixed-panel cosine efficiency and the fact that PV-usable sunlight is nowhere close to 12 hours per day and the fact that conversion from relatively low level DC voltage to high voltage AC is required to connect into the major grid transmission lines.
There is also the fact that to be comparable to on-demand sources such as coal and natural gas electric-power generating plant, the cost of massive electrical storage batteries should be factored into the cost of electricity from solar PV power plants.
Given the above, it seems like the LAST thing one would want to do is to float solar PV panel arrays on water! Up go the installation costs, up go the infrastructure costs, up go the maintenance costs, etc.
Yeah, screw all those migratory birds, fish, and other wildlife. We need to virtue signal.
The solar farms will reduce sunlight and oxygen flow in to the lakes. This will have dire consequences for the aquatic ecosystems in those lakes. As for the mix of electricity and water- it is a disaster waiting to happen. Could you imagine the stink when a storm destroys the installation, sending the panels to the bottom of the lake to release the heavy metals from the now destroyed panels. It could result in the lake water becoming unsuitable to drink in the long term!! The cities that rely on that lake water will suddenly have no water supply!!
The risk is just way too high to take. Mind you, the UN have a thing against dams. If dams get contaminated by solar panels, just where are we going to source clean drinking water? How many humans will the planet be able to support if lakes get contaminated by this folly???
This is a really stupid idea, in so many ways.
And cutting off the sunlight to the lake will have no effect on the photic zone and all the other members of the lake ecosystem? Jeez, these people are stupid.
“Lets’ go kill the lake and pretend we are saving it by making green energy and leaking heavy metals into the lake, thus killing EVERYTHING in it. Sounds like a great plan.
Climate has gone up and down for millions of years and they think they have to save the lakes. HUBRIS.
When the next glacial period hits, half of North America will be obliterated, but a degree or two and we are supposed to panic. Idiots.
Charles,
I think these guys are secretly jealous of all the environmental disasters the Soviets and Chicoms have gotten away with over the years. Not content to chomp up a few thousand hawks and eagles, as well as countless bats, every year; they now want to try to out do the Lake Baikal disaster and the possible failure of the Three Gorges Dam!
Yes, once you have the solar panels in place, the electricity is cheap, but you have to be an adult and pull up your adult pants and realize that the synthetic materials, heavy metals, mining of heavy metals, the infrastructure of the solar panels and delivering it to the user, and the short lifetime of solar panels, as they dwindle in efficiency, the leaking of heavy metals into the environment as the panels age, and the disposal of huge mountains of un-recyclable dead solar panels all have to be included. Oh, and the ecological foot print of these panels is obscene. Yeah, cheapest energy on the planet, if you are in first grade and believe every lie they tell you.
Wind and solar are the least green energies on the planet, period.
Electricity from solar is not cheap at any point, it is vastly expensive.
Wind is anything but cheap. The capital cost is ridiculously high, the life expectancy low, the disposal all but impossible.
Solar cost about 35 cents kilowatt to produce amortizing in the capital and installation cost, coal about a penny.
Winter should be fun.