Tidal energy could be huge – why isn't it?

Summary

Off the coast of Scotland, tidal turbines harness the energy of moving water with the tides, offering a predictable and powerful renewable energy source. Tidal power has the potential to significantly contribute to global energy needs, but currently, it powers less than 400,000 homes worldwide. Challenges include high costs, environmental impacts, and the need for substantial infrastructure. However, advancements in technology and supportive policies could make tidal power a competitive and eco-friendly solution for coastal and island nations.

Takeaways

• 🌊 Tidal power harnesses the energy from moving water caused by the rise and fall of tides.
• 💡 The potential of tidal energy is enormous, enough to power all homes in the United States twice over.
• 🔍 Existing tidal power plants worldwide can currently power less than 400,000 homes.
• 🌕 Tides are highly predictable due to the gravitational pull of the moon and the Earth's rotation.
• 💧 Tidal power generation involves placing turbines in the water to convert the kinetic energy of moving water into electricity.
• 🏭 Tidal range power uses the difference between high and low tides, often by building a dam across a bay or estuary.
• 🌉 The oldest tidal range generator, La Rance in France, has been operational since 1966 and is still producing power.
• 🌍 Top regions for tidal range power include the Bay of Fundy in Canada, the Northwest Australian Shelf, and the Northwest European Shelf.
• 🚧 Infrastructure and geography are significant barriers to the widespread adoption of tidal range power.
• 🌿 Environmental concerns, such as impact on migratory fish and local ecosystems, have led to opposition against large-scale tidal power structures.
• 💸 The cost of tidal power is currently high, but the industry is working towards making it commercially viable and competitive with other renewables.

Q & A

What are tidal turbines?

Tidal turbines are devices that sit on the seafloor and harness the energy in the moving water that comes in and goes out with the tides.

How much energy could tidal power potentially capture?

It's estimated that tidal energy could be captured enough to power all homes in the United States twice over.

Why isn't tidal power more widespread despite its potential?

Tidal power is not widespread yet due to the high costs of installation, the need for specific geographic conditions, and the relatively young industry with fewer established supply and manufacturing chains.

What is the principle behind tidal power generation?

Tidal power generation works on the principle that moving water makes the turbine spin, which then powers a gearbox and a generator to turn mechanical energy into electricity.

What is the role of the moon in causing tides?

The moon's gravity pulls at the Earth and water, causing bulges towards it, which results in the tide coming in or going out.

How predictable are tides and how does this benefit tidal power?

Tides are highly predictable and consistent, which allows for easier integration into the energy grid compared to less predictable renewable sources like wind and solar.

What are the two main ways to extract power from tides?

The two main ways to extract power from tides are tidal stream power, which uses underwater currents, and tidal range power, which takes advantage of the difference between high and low tides.

What is the significance of the La Rance tidal range generator?

La Rance, built in 1966 in France, is the oldest tidal range generator and is still operational, providing power for a town of around 250,000 inhabitants.

What are the environmental concerns associated with tidal power plants?

Environmental concerns include the potential disturbance of migratory fish, changes in soil composition, and the impact on local communities and marine life.

How do tidal stream power projects differ from tidal range power?

Tidal stream power projects use underwater currents caused by tides and can have simpler devices like breeze turbines, underwater kites, or floating stream turbines, whereas tidal range power involves building dams across regions where seawater meets land.

What are some of the engineering challenges associated with tidal power?

Engineering challenges include the need for robust materials to withstand corrosion and biofouling, the high costs of underwater operation, and the potential impact on marine life.

What is the current state of tidal power in terms of cost and efficiency?

Currently, tidal power is more expensive than other forms of renewable energy, but the industry is working towards reducing costs to make it commercially viable, with a target of $0.10/kWh by the end of the decade.

Outlines

00:00

🌊 Tidal Power: Harnessing the Sea's Energy

Tidal power is a renewable energy source that uses the predictable movement of water caused by the gravitational pull of the moon. Tidal turbines, similar to wind turbines, are placed on the seafloor to convert the kinetic energy of moving water into electricity. The potential of tidal power is enormous, with enough energy available to power the United States twice over. However, currently, tidal power plants only provide enough energy for around 400,000 homes. Tidal power is advantageous due to its predictability, unlike wind and solar power which can be less consistent. The tides are a result of the moon's gravity causing the Earth's water to bulge towards it, creating high and low tides. Tidal range power plants use the difference between high and low tides, often building a dam across a bay to capture the energy as water flows through turbines. The oldest tidal range generator, La Rance in France, has been operational since 1966 and is still providing power. However, the infrastructure for tidal power is not widespread, and the environmental impact of such structures can be significant.

05:01

🏭 Tidal Range Power: Innovations and Challenges

Tidal range power plants face challenges such as the need for significant geographical features like bays or estuaries with significant tidal ranges, which are not universally available. Infrastructure to support these plants is also lacking in many areas. Moreover, there are environmental concerns as these structures can disrupt local ecosystems, migratory fish patterns, and soil composition. However, advancements in tidal range power are being made, such as a project in Wales that uses only a part of a lagoon to minimize environmental impact and includes space for aquaculture and sports. Despite these challenges, tidal range power accounts for 98% of tidal energy production today, with a combined capacity of 520 megawatts. Tidal stream power, a newer technology, is gaining traction with simpler devices that harness underwater currents. Various designs, such as breeze turbines and underwater kites, are being tested, with some achieving record-breaking energy levels. However, the cost of tidal power remains high, and the industry is young with unique engineering challenges, including material selection to prevent corrosion and biofouling.

10:03

🐠 Environmental Impact and Future of Tidal Power

While tidal power has the potential to be a significant contributor to clean energy, it also has environmental implications. The La Rance project in France, for example, led to a decline in two fish species' populations. Tidal stream projects are generally more eco-friendly, with turbines that rotate slowly, reducing the risk of harm to marine life. However, there are concerns about displacement, where animals may avoid areas with turbines, affecting feeding grounds. Despite these concerns, the environmental impact of tidal power is considered less severe than that of climate change. Tidal power offers benefits such as a predictable supply of clean energy and minimal visual impact on coastal areas. The challenge is to reduce costs and make tidal power commercially viable. Currently, government support and investment in tidal power are limited, with less than 0.02% of annual investment in renewables allocated to tidal energy. The industry aims to reduce the cost of tidal power to $0.10/kWh by the end of the decade, making it a more competitive renewable energy source.

Keywords

💡Tidal Turbines

Tidal turbines are devices that harness the energy of moving water caused by the rise and fall of tides. They are anchored to the seafloor and convert the kinetic energy of tidal currents into electrical power. In the video, tidal turbines are highlighted as a means to generate clean, renewable energy with the potential to power homes. The script mentions that these turbines can be smaller and slower than wind turbines yet produce more power due to water's higher density compared to air.

💡Tidal Power

Tidal power refers to the generation of electricity from the movement of ocean waters due to tides. It is a form of hydropower that takes advantage of the predictable rise and fall of sea levels. The video emphasizes the vast potential of tidal power, suggesting that it could theoretically power all homes in the United States twice over. However, currently, it powers less than 400,000 homes worldwide.

💡Predictability

In the context of the video, 'predictability' refers to the consistent and reliable nature of tides, which occur in a regular cycle due to the gravitational pull of the moon. This predictability makes tidal power a more reliable source of energy compared to wind or solar power, which can be intermittent. The script highlights that tides are 'really, really predictable and consistent,' which is a significant advantage for energy grid integration.

💡Tidal Range Power

Tidal range power is a method of harnessing tidal energy that takes advantage of the difference between high and low tides. The video explains that this is achieved by constructing a dam across a bay or estuary, allowing water to flow through turbines when the tide comes in or goes out. An example given is the La Rance plant in France, which has been operational for decades and provides power for a town of around 250,000 inhabitants.

💡Tidal Stream Power

Tidal stream power is a type of tidal energy generation that uses underwater currents caused by the tides. The video describes it as 'younger and sexier' compared to tidal range power, with simpler devices like underwater breeze turbines. Tidal stream power is currently showing more promise, with projects in Scotland supplying record-breaking levels of clean energy to the UK grid.

💡Energy Density

Energy density, as mentioned in the video, refers to the amount of energy that can be stored in a given system or medium. Water is over 800 times denser than air, which means that tidal turbines can be smaller and slower than wind turbines but still produce more power. This concept is crucial for understanding the efficiency and design of tidal turbines.

💡Grid Connectivity

Grid connectivity in the video refers to the integration of tidal power plants into the existing electricity grid. It is mentioned that not all locations are suitable for tidal range power plants due to a lack of grid connectivity or low population density. This factor is crucial for the economic viability of tidal power projects.

💡Environmental Impact

The environmental impact of tidal power is discussed in the video, with concerns about how the structures can affect local ecosystems, migratory fish, soil composition, and占用 local community space. However, newer projects are designed to minimize these impacts, such as the one in Wales that uses part of a lagoon to protect local ecology.

💡Commercial Viability

Commercial viability in the context of the video pertains to the economic feasibility of tidal power projects. It is noted that the challenge for the tidal power industry is to reduce costs to make it a competitive form of renewable energy. This involves investments, government support, and subsidies to bring down the price tag and make tidal power a commercially viable option.

💡Life Cycle Costs

Life cycle costs refer to the total costs associated with a product or system over its entire lifespan, from production to disposal. The video mentions that the industry targets reducing the life cycle costs of tidal energy to $0.10/kWh by the end of the decade, which would make it a cost-effective and competitive form of renewable energy.

💡Marine Life

Marine life is discussed in relation to the potential impacts of tidal power installations on aquatic ecosystems. The video contrasts the effects of tidal power with those of climate change, suggesting that while there will be environmental effects, climate change poses a far greater threat. Tidal stream projects are highlighted as being more eco-friendly, with slower-moving turbines that are less likely to harm marine life through collisions.

Highlights

Tidal turbines harness energy from moving water caused by tides.

Tidal power has the potential to power all homes in the United States twice over.

Existing tidal power plants worldwide can currently power less than 400,000 homes.

Tides are highly predictable due to the consistent gravitational pull of the moon.

Tidal power generation works by using the flow of water to spin turbines, similar to wind turbines.

Tidal turbines can be smaller and slower than wind turbines but produce more power due to water's density.

Tidal range power takes advantage of the difference between high and low tides, up to 12 meters.

Tidal range power plants can operate for 18 to 22 hours every day.

The oldest tidal range generator, La Rance, has been operational since 1966 in France.

Tidal range power plants require a minimum tidal range of five meters to be economical.

Infrastructure and geography are significant factors in the placement of tidal range power plants.

Tidal stream power is a newer, simpler method that uses underwater currents caused by tides.

Tidal stream power devices include breeze turbines, underwater kites, and floating stream turbines.

Tidal power is expensive due to the young industry and unique engineering challenges.

The industry aims for tidal power to be commercially viable with costs falling to $0.10/kWh by the end of the decade.

Tidal power has less environmental impact compared to climate change, according to research.

Tidal power can play a significant role in coastal or island nations achieving net-zero goals.

Transcripts

Off the coast of Scotland, you could witness this.

Wind turbines being put into the water.

They're called tidal turbines.

They sit on the seafloor and harness the energy in the moving water

that comes in and goes out with the tides.

"Tidal power is just kind of sitting there and waiting to be used."

The potential is huge!

It's estimated that we could practically capture enough tidal energy

to power all homes in the United States twice over.

"My research with climate change shows

we need this energy now."

Yet, at the moment, all the energy we get from existing tidal power plants

worldwide can power less than 400 000 homes.

So how does tidal power work exactly?

And why isn't it everywhere yet?

With tidal power, there's one word that comes up a lot:

"Predictable."

"Predictable."

"Predictability."

Tides are predictable, they come in, they go out

and they've been doing this the same way since the moon was born.

But before we jump into how it all works,

let's do a quick high school science refresher on the tides.

The moon's gravity pulls at the earth,

and water which can move more freely than solid ground

begins to bulge towards it.

On the other side, a differential force by the earth's own gravity

causes an opposing bulge too.

When the earth aligns with the moon and the sun,

the sun's gravity makes the bulge even more intense.

So the earth rotates through the bulge

and wherever you are in the world

you are either entering the bulge or leaving it behind,

which looks to us like the tide is coming in

or going out.

This cycle happens around twice a day.

In case you're wondering what happens

when the moon is in a different phase:

the bulge just gets weaker.

Tidal power takes advantage of these tides.

Other ocean technologies also look at waves

and ocean currents.

But that's a whole other story for later...

So, with the tides stick a turbine in the water

as it flows in or out, and voilà!

You can make electricity

with the same principle that wind turbines use.

Moving water makes the turbine spin, this powers a gearbox

and a generator which turns mechanical energy into electricity.

Water, incidentally, is over 800 times denser than air –

which means that tidal turbines need to be sturdier,

but they can be smaller and slower and still individually produce

more power than wind turbines.

So far so good?

Then back to tidal's trump card: predictability.

Wind starts and stops blowing somewhat randomly

and the sun isn't always out.

So these renewables can be difficult to integrate into the grid.

Tides, as we know, are really, really predictable and consistent.  

So if batteries are charged when tides are flowing,  we could use those batteries each time there's no  

movement and repeat at regular intervals.

The other option is fossil fuels

but let's not even go there.

With tides, two main ways to extract power exist.  

One's called tidal stream

and the other tidal range.

Let's talk about tidal range power, that takes advantage of the

difference between the high and the low tide,

which can go up to 12 meters.

This works by building a dam across a region

where the seawater meets the land.

The shape of these bays or estuaries magnifies

the difference between the high and low tide.

How it actually works is the gates of the dam are first shut  

until the difference in the water level

builds up to the highest point.

And then the water is allowed to flow in.

As it does so, a turbine below collects

and converts all that delicious energy into electricity.

Many tidal plants can actually work

when the water flows the other way too,

which means they could work for between

18 and 22 hours every day.

And this kind of tidal power has been around for decades.

The oldest tidal range generator, La Rance,

was built in northern France in 1966.

It cost around $1 billion in today's money,

which is cheaper than a comparable nuclear power plant,

but higher than the cost of installing other renewables.

But it's still going strong, producing enough power

for a town of around 250 000 inhabitants.

And the electricity from La Rance is

actually cheaper than solar and nuclear.

There are four other tidal range plants running

in South Korea, Russia, Canada and China.

"You could put a tidal range power plant anywhere

but it wouldn't be economical to put it somewhere

where there's minimal tidal range."

Simon Neill has spent years watching the tides ebb and flow

and he says the golden number for the range

to make sense for a project is five meters,

which happens because of some quirks in geography

including the width of the continental shelf

and the depth of the ocean.

"Top regions are the Bay of Fundy in Canada,

the Northwest Australian Shelf,

the Northwest European Shelf

and the Patagonian shelf.

But they're not all suitable. So, for example, there may not be

much grid connectivity or the populations may be quite low."

So apart from geography, the infrastructure to support

tidal range plants just doesn't exist everywhere.

And people have opposed the massive structures

because they can be horrific for the local environment,

disturbing migratory fish,

the composition of the soil,

and even taking space away from local communities.

But things are changing for tidal range power.

A project commissioned in October 2021 in Wales

takes the idea out of the 1960s and applies it to today.

When environmental damage is much less acceptable,

the design doesn't block off an entire bay

but only uses a part of a lagoon,

so the local ecology is protected.

And it's expected to generate even more power than the French plant.

The proposal also includes space for aquaculture and sports,

so the area can remain a shared resource.

Ninety-eight percent of tidal energy today

comes from tidal range projects

that together have a capacity of 520 megawatts,

which is still a tiny, tiny fraction of our consumption.

But the other kind of tidal power generation

could shake things up!

The younger and sexier kind on the market:

Tidal stream power.

It's showing more promise at the moment,

with its simpler devices that depend on

underwater currents caused by the tides.

They vary in shape and design.

The most common are breeze turbines,

like wind turbines, that can be set up

in clusters in wind farms underwater.

A couple of research and development zones in

the north of Scotland supplied record-breaking

levels of clean energy to the UK grid this year, powering over 12 000 homes for a year.

Then, there's an underwater kite that flies in a figure of eight.  

Like the wind lifts a kite, currents in the

water speed it up in turn producing more energy.

And then there are floating stream turbines.

The most powerful of which was recently launched in Scotland

with an individual turbine capacity of two megawatts.

They're tethered to the seafloor

but the turbines remain close to the surface

which means the undersea work is cheaper

and they can be moved around.

Compared to wind or solar energy though,

tidal has been slow for a reason you might have guessed.

"Sadly, a lot of the solutions are really expensive."

Amanda Smythe is the go-to tidal researcher

at Oxford University, who believes tidal's time will come.

"Because the industry is so young,

so it's a very small industry, you know,

it doesn't have an established

supply chain or manufacturing chain."

"Anytime you're going to operate something underwater,

that has its own unique set of engineering challenges.

Your standard ones, like corrosion,

are going to be a big problem.

So you're gonna have to choose your materials really carefully.

Biofouling is a really big issue where,

you know, you put something in the water

things are gonna wanna grow on it

and it's gonna make it into a little mini reef,

a little habitat.

The performance of the turbine will deteriorate

so you need to find some way of preventing that.

That's a huge operational cost."

Which is why most tidal stream generation projects

cluster in the Global North,

where financial support to test the technology

at this stage exists.

China and South Korea are joining in but  lower-income countries, like India, have been slow or  

dropped plans to try out tidal power.

But they could benefit when the costs of deployment

begin to fall.

"The challenge now is to bring down the price tag of it –

to make sure that it's something that's commercially viable –

and this is where things like sort of

investments and government support

and subsidies can be extremely impactful.

There's a number of proven concepts

and there's a number of companies

that have a technology ready."

While the UK and Canadian governments

have been the biggest investors in tidal power,

overall, grants and government investment have been slow,

with less than 0.02% of annual

investment in renewables reaching tidal.

And so it's been behind the curve in other ways too.

Electricity from underwater tidal turbines can cost up to

nine times that produced by turbines above the surface of the water.

But the industry targets that life cycle costs could fall to $0.10/kWh

by the end of the decade, which would be pretty cheap.

But apart from cost what actually happens

when you put these turbines underwater?

Oceans are abundant with marine life.

The structure of the La Rance project from earlier decimated

the populations of two fish species.

And, like wind turbines, that have been known to

cause the lungs of bats flying past to implode –

the pressure difference caused by tidal barrages could have a similar effect on the internal organs of fish.

But tidal stream projects are already more eco-friendly.

"Tidal turbines turn quite slowly.

So, the idea of things getting chopped

is probably not going to happen.

Things getting hit?

Yes, that can happen, especially at tip speeds.

The big problem is not, probably, going to be collision.

The problem is going to be displacement –

that animals will avoid these areas and therefore not use these areas to feed in.

And these faster tidal areas are areas that seabirds,

mammals and fish species do feed in."

Beth Scott studies the impact of tidal power

on marine life around the world.

"We've compared it to climate change –

and even by 2050, what you see is

climate change is 10 times worse than

taking the maximum amount out of tides.

And when we model that against animals

and animal distributions,

what we see is climate change is by far the worst enemy.

So yes, these things will have environmental effects.

But we should put them in that context of climate change."

Tidal has other benefits too.

While its financial cost is still higher than other renewables,

its net benefit could actually be higher when you consider

things like its predictable supply of clean energy to the grid,

or the fact that stream projects

don't visually affect a beautiful sea view.

So especially in coastal or island nations,

tidal does have the power to play

a significant role in getting to net-zero,

in a relatively less disruptive way.

The need of the hour is to make tidal power competitive.

The world is abundant with natural resources

as well as big ideas on how to preserve them.

We try to bring you the best ones

so come back and watch every Friday!