We need less of this...
And more of this...
to stay below 1.5 degrees –
but time is running out!
"We are sleepwalking [into the] climate catastrophe."
"Code Red! to the G7 countries!
Code Red! to the G20!"
Solar still only accounts for 3.7 percent of worldwide energy production.
We desperately need more.
But, where can we put the solar panels?
They need space on precious land –
Land we need for:
towns,
houses,
and streets,
intact ecosystems,
and food.
So how about putting them on existing farmland?
Or on water?
Or why not harvest the sun's energy much closer to it?
What's the best way to build more solar panels
without losing much-needed space?
Let's start back on earth.
Here we have a serious space issue.
We're already using a lot of our soil to grow food.
But what if we grew crops and generated energy at the same time?
It's time for:
Agrivoltaics.
The idea behind it:
double the harvest!
To do this, modules are built in such a way
that the soil beneath them can still be used for growing plants.
"Whenever people hear about this,
the primary reaction initially is: really?
This is Grag Barron-Gafford.
He is an earth system scientist and researches
how agrovoltaics work for different regions.
"And the second one is well, that makes so much sense.
Why haven't we been doing it forever?"
Yes, why?
And what potential types are there?
One is solar fences.
The space in between the fences can be used to grow crops,
for livestock or for flower strips.
Or the modules could be built in a way that gives the panels
enough space to rotate towards the sun.
Or high enough for farmers to be able to walk
and work beneath them...
and even enjoy some shade when the sun is really blazing.
But how do plants fare growing under, or near, the panels?
"We've been growing lots of different kinds of crops –
things that you would see at your local farmers market.
So tomatoes, peppers, squash, aubergines,
all of these different types of crops have seemed to do really well."
So the plants still get enough light.
Tomatoes and chili peppers even doubled their yield when shaded by solar panels.
That's because, if they get too much sun,
they get stressed and stop photosynthesizing.
Which means they stop growing.
Farmers can use the generated solar energy directly on their farm
or they can sell it to others in the local area.
Another plus: The photovoltaics – or PV panels –
protect the plants growing underneath them from heavy rain and hail.
Climate change means such extreme weather events are on the rise.
One study conducted by the US department of energy found
that 95 percent of tested PV modules resisted hail undamaged.
And they're also useful in other extreme conditions:
In a world that is getting hotter and hotter,
the modules ensure that less water is needed for irrigation.
"Just think if you spilled your coffee or your water,
your tea in the shade versus the full sun.
Where will it stay wet longer?
In the shade.
We're finding that every time we irrigate it,
it would stay wet for two days instead of two hours."
So the panels help save water and protect the plants from overheating.
And it works the other way around too:
with the green plants cooling the underside of the modules
making them more effective.
Interest in agrivoltaics is growing across the world.
Not only in Europe, but also in India, Japan, China and many other countries.
And dry regions in particular can really benefit from the combination technology.
But...
yes there are a few buts:
Not everything can be grown under the panels.
Crops like wheat or millet require full sun to grow well.
Researchers are looking into which panels and setups would be best for which crop.
Some plants need bigger gaps between the panels.
Corn and wheat would need taller ones,
while shrubby soybeans would be fine with a more squat variety.
Another issue: although solar power offers an attractive return,
investment costs are still more than double those of ground-mounted PVs.
And you can't use an entire field to grow food –
the panel mounts take up between 1 to 12 percent of the space –
depending on the crop and the PV system.
But the trend for the coming years is promising.
According to a market analysis institute, the global market is anticipated to
grow by almost 40 percent in the next 5 years.
In dry regions or those that rely heavily on agriculture
like India, Indonesia and many African and South American countries,
agrivoltaics could save a lot of land and water.
Combining solar panels and farming is one way to solve the space problem.
Another is to take the plunge...
and fit the solar panels on water!
Floating photovoltaics or floatovoltaics might just be the next big thing.
The idea: Solar panels are mounted on raft-like structures
which float on a body of water.
"Only a 10 percent coverage of all the reservoirs which are
available in the world would give about
23 terawatt peak of installed capacity."
This is Thomas Reindl.
He evaluates the economic and technological
feasibility of large-scale floating PV systems.
"And to put this into perspective,
these 23 terawatts would generate as much
electricity as the whole world needs today in a year.
You can already see what that could
look like at one of the world's biggest floating solar farms in Singapore.
Here the solar plant floats on the surface of a reservoir.
And produces enough energy to power about
16,000 four-room flats in the city-state.
The biggest floating farm in China
even produces five times as much energy.
And that's not all.
Underneath the solar panels, you can farm fish
in aquaculture pens, which can generate additional income.
Floating PV projects may be particularly useful on hydropower dams.
During the summer season solar panels can generate electricity – and when it's wet,
hydropower can kick in...
The water also cools down the floating panels, making them more efficient.
And by protecting the water surface from the sun, the panels reduce evaporation –
a real gain in times of climate change when water is becoming ever-more precious.
Water scarcity is a huge issue especially in arid regions like Sub-Saharan Africa,
South East Asia or the Middle East.
In extreme cases up to 90 percent of rainfall can be lost through evaporation.
Floating solar panels can help with this.
According to a study in Jordan the use of floatovoltaic panels on reservoirs,
can reduce water loss by 42% compared to uncovered ones.
And using such panels on inland water bodies is just the beginning.
"They are aiming for these vast spaces,
ocean spaces in between offshore wind farms.
So in offshore wind farms that powers are spaced very far apart.
And then the spaces in-between can actually be used for
floating solar and then you can use also
the existing transmission infrastructure,
which is already there for the wind farm."
And floating the panels on oceans is even more effective than on reservoirs.
Ocean panels generate up to 13 percent more energy because the ocean cools the
system more than a lake or lagoon could.
No land use, more efficient energy generation, less water evaporation
and additional profits from fish farms.
Why are we been only doing this now?
Partly, because of the COST.
Floating solar needs specialized equipment
and specially-trained installers.
The panels and structures have to withstand wind, waves, and corrosion.
Meaning they have a shorter lifespan than those on land.
This makes the electricity they generated 2 to 20 percent more expensive today.
But experts say, that the price will go down significantly in the future.
"One other aspect is the environmental impact on
the reservoir and on the on the nature.
So this is something which there is no clear answer to
that every single project needs to do a very
detailed environmental and social impact assessment study."
On the one hand, floating PV can reduce algae blooms –
lowering health risks and water treatment costs.
But changes to water chemistry CAN
also cause nitrification and loss of oxygen.
So far, though multiple studies have not found any
severe impact on either water quality or ecosystems.
Experts expect floatovotaics to expand by up to
30 percent annually 1over the next five years,
with markets mainly in Asia.
But Europe, Africa and the US are starting to invest as well.
"It's very encouraging to see that some of the largest projects
in the world have obtained Bank Financing
and that's a major breakthrough."
So there's a good chance that a floating PV will
soon be coming to a waterbody near you.
Or in other words...
"Get into floating solar. The ocean is the limit."
So, any other places left to put solar panels?
Here?
There?
Or here?
No!
Up in space!
Yep, getting as close to the sun as possible.
Here the sun shines 24 hours a day
and you need zero land on earth.
So why don't we put solar panels in the earth's orbit?
The idea first appeared in the short story "Reason" by Isaac Asimov in 1941.
In the story, two engineers are assigned to a space station
which supplies energy to planets via microwave beams.
And now, the UK-led Space Energy Initiative with around 50 partners
from industry, government and science
are planning to install a solar power satellite in space by 2035.
The US, China and Japan are also taking part in the solar space power quest.
And this is how it might work...
Satellites in the earth's geostationary orbit,
which is around 35,000 km from earth,
collect solar energy using huge solar panels.
They convert the energy into microwave radiation and beam it down to earth.
On the ground a net of receiving antennas – or rectennas –
collect the microwaves and convert them to electricity for the grid.
First tests have shown that it works!
The microwaves can pass through clouds or rain –
because they have the same frequency as WIFI on earth.
Each satellite might produce 2 GW of continuous power –
as much as around 700 Utility-Scale Wind Turbines.
They'd be huge – around 1.7 km in diameter
and will weigh several thousand tons.
They'd be transported into orbit by a fleet of reusable rockets.
Robots could then puzzle the single modules together in space.
Once finished, the satellites would start
to beam energy to earth 24 hours a day.
The beam is considered to be harmless for animals and humans.
It's about a quarter the strength of the midday sun.
But, energy is lost during the transmission –
and the conversion process –
and the costs of getting the modules into space is...
well...
sky-high!
Today taking even one KILOGRAM of weight up into space costs around $3000.
Although the basic technical possibilities are there,
the satellites have not yet been tested on a large scale.
They'd also better never break down –
around 35,000km from earth the satellites will
be nearly impossible to repair and maintain.
But even if we manage to build and finance
solar power satellites in the next decades,
we need more solar power to combat climate change NOW.
And there are already far more realistic ways of generating solar energy quickly
WITHOUT losing urgently-needed land.
And all of them are cheaper, faster and much more promising.