The world's last free flowing rivers are under threat.
What's commonly thought of as a green solution to the energy crisis
is destroying the planet's last remaining pockets of untouched wilderness
and intact ecosystems.
Before we start, we'd like to tell you that this video is part of a collaboration
with the YouTube channel "Undecided with Matt Ferrell".
Matt explores how sustainable and smart technologies impact our lives.
This time, he's diving deep into the technology behind hydropower,
which we will tell you more about later on.
Today, there are roughly 60,000 large dams around the world.
3,700 more are currently planned or under construction.
Over 500 of them will be built in protected areas.
At first sight, the concept of hydropower is a simple one.
Flowing water is trapped in front of dams,
then directed through turbines, which spin to generate electricity.
It may seem like a green solution
to meeting the world's growing electricity demand,
but it's actually a dirty one.
Dams emit greenhouse gases,
endanger fish species and can uproot communities.
So, all this leads us to the question:
What is the true cost of hydropower?
To understand the environmental impact of hydropower,
we first have to understand the value and characteristics
of a free flowing river.
In a wild river, animals, such as migratory fish,
can swim up and downstream at will.
Groundwater and aquifers naturally refresh the water,
silt and other natural materials can move along freely.
The water moves out onto the floodplain in harmony with the seasons,
delivering important nutrients to wildlife and other habitats,
signaling fish to spawn
and bringing nutrients back into the river itself.
The sad news is that there aren't many wild rivers left,
two thirds of them are already dammed
and that number is increasing every day.
What started with old fashioned waterwheels
has developed into modern hydroelectric plants
embedded in dams to generate power.
Currently, 22% of the world's electricity is provided by renewable resources,
73% of which is hydropower.
But although hydropower is renewable,
it isn't green.
Building a large barrie like a dam
destroys the single most important thing about a river:
its flow.
Both the reduced downstream flow and the reservoir upstream
can destroy wildlife habitats and farmland,
either through drying out or flooding.
A dam also changes the structure of a river.
It slows the flow of water,
which means that sediments like sand or gravel
hit the dam and then drop to the riverbed.
In a way, dams are thus creating big underwater sandboxes.
And these are bad news for fish,
which depend on clean, rocky bottoms.
The clustered sediments aren't good for the dam itself either,
because as the area in front of it is filled up with more and more sediment,
it holds less and less water.
Dams don't just form a barrier for sediment,
but also mean a drastic impact on flora and fauna.
When the flow of a river is blocked,
fish can't reach their spawning grounds
and over time, dammed rivers can lead to drastically reduced fish populations.
Currently, the most common way of solving this migration problem
is installing fish ladders.
Fish ladders are stepped pools
which allow fish to swim or jump from one pool to another
all the way up and behind the dam.
But in most cases, they don't actually work very well.
The structures are often too high or too steep,
too small to support massive migrations or not able to hold enough water.
Even if fish ladders do succeed,
they might work for fish like salmon,
but not for all types of fish
because some, like eels, can't jump.
Blocked migration routes aren't the only problem.
Reservoir water usually contains an excess of algae
or other aquatic weeds,
which can crowd out other animal and plant life.
The water in reservoir is typically also low in dissolved oxygen
and colder than normal river water.
When this water is released from time to time,
it can have a bad impact on wildlife.
As a result of all these negative consequences,
worldwide populations of freshwater species
have already experienced a staggering 83% decline since 1970.
More dams will likely further deplete their numbers.
Despite all these aspects,
there's a popular consent that hydropower is a vital element
for the energy industry's shift away from fossils,
but one fundamental piece of information is missing from the argument.
It might sound counterintuitive at first,
but hydropower is not emission free.
Around 10% of the world's hydropower facilities
emit as many greenhouse gases as conventional fossil fueled power plants.
Some existing dams in the lowland Amazon
have even been shown to be up to 10 times more carbon intensive
than coal fired power plants.
Generating power by spinning turbines with water
doesn't directly emit greenhouse gases.
So, where do they come from?
When reservoirs cover organic matter
like dead plants, trees, fields and farmland,
they produce greenhouse gases,
especially in warm climates.
The organic material breaks down and releases gases
like carbon dioxide and methane into the reservoir water.
And these are the two major greenhouse gases
associated with climate change.
Worldwide, the rotting vegetation in reservoirs
represents 1.3% of the total annual global emissions caused by humans.
This is alarming,
but it also shows that there's potential to improve the current situation
and here's how.
Hydropower needs to be viewed as part of a broader strategy for energy
in which the costs and benefits of different sources
should be assessed and weighed against each other.
A strategic mix of solar, wind and storage technologies around river basins
could be an option.
Greater investments need to be made in detailed upfront planning
and environmental impact assessments,
which should be carried out by independent scientists.
Existing dams should be upgraded
and retrofitted where possible instead of building new ones.
And fish passage systems need to be optimized
to make it more friendly for all different kinds of fish.
Sounds like a lot of work, right?
But it's finally getting started.
In October 2020, several environmental groups
and the industry that operates America's hydroelectric dams
announced an unusual agreement to work together
to reduce the environmental harm caused by dams.
They're also going to join forces
to remove older dams that are no longer needed.
More than 1.000 dams nationwide have already been torn down in recent decades.
In many of these places, such as the Elwha River in Washington state,
nature has come roaring back,
with fish populations increasing.
It's expected that if this trend continues,
between 4,000 and 36,000 more dams
will have been removed in the U.S. by 2050.
The world's free flowing rivers are crucial for the environment and humans alike.
And it's now more important than ever that we choose wisely
whether we really want to build new dams.
It's about finding the right balance
between hydropower and rivers,
but also more generally between energy consumption
and ecosystem conservation.
Hi there.
Be sure to check out the video from "Undecided with Matt Farrell".
He talkes about the technical solutions
which can make hydropower more environmentally friendly.
Matt hast done an amazing job.
You will see detailed animations of new tools and technologies
and examples for tidal energy.
We have a link to the video right here.