that the oceans are actually the largest battery.

We're storing huge amounts of energy in the oceans.

The wave motion can be very deep.

It can extend down several hundred meters,

and once it gets to the near shore, from about 50 meters,

the whole water column is moving backwards and forwards.

As we search for ways to reduce our reliance

on fossil fuels, some are looking

to a largely untapped potential source of renewable energy.

In theory, waves off the coast of the United States alone

could generate over two trillion kilowatt hours

of electricity a year,

enough to power more than half of the country.

Waves intensify and subside not as quickly as the wind,

and that means that it can produce

a smoother power generation curve.

One of the potential advantages of wave energy is

that it could act as a complementary source of power,

compared to other renewables on the grid

if it were to be scaled up to a commercial scale.

For decades, engineers have been trying

to convert wave energy into electricity

but a host of technological

and financial challenges have complicated their efforts.

In the years from around 2006 to 2015,

there were a spate of bankruptcies in the sector,

and this was largely because of a lack

of kind of continuous proven projects out at sea

with reliable electricity generation.

Since then, companies have been trying

to develop the technologies at a steadier pace

and with a smaller cash burn.

But the same questions remain.

Can companies develop devices

and technologies that actually work?

Is wave energy just a novelty or something

that can become a major renewable energy source?

The sea is a very challenging environment

within which to operate a power project.

So seawater is corrosive and conditions are very rough.

So this means that power projects

don't have a very long lifetime

and it increases operating and maintenance costs.

Partly because of that,

many early wave energy projects hit rough waters,

such as the Pelamis wave energy converter in Portugal

and the Islay LIMPET project in Scotland,

but that hasn't stopped others from trying.

Companies are focused on testing projects out at sea,

proving their durability, trying to raise capital

and bring down cost.

The sector hasn't really converged

around one single technology design

and companies are kind of undecided

about which design works best.

Finland-based AW Energy is a veteran in the sector.

The first proof of concept of the company's device

was made in the '90s after diver Rauno Koivusaari

observed the strong back and forth movement of a hatch cover

in a shipwreck in the Baltic Sea.

The waves are generated far from the coastline.

So the wind blows on the surface of the water

causing the water particles to rotate.

And that rotation extends deep down below the surface

and the waves can be very long,

they can be several hundred meters long,

and as they come into the near shore,

this rotational energy turns into an elliptical energy

and eventually backwards and forwards

that you probably have noticed if you've been swimming

on the seashore in large waves, you're pulled in and out.

That's the energy that we're extracting

but there's a sweet spot where we deploy.

So around 10 to 15 meters of water depth,

that's where there's still strong wave energy coming in.

After years of research, prototyping and testing,

the company has deployed WaveRoller,

a 350-kilowatt device in the waters off Portugal.

WaveRoller has an 18-meter wide

and 10-meter high steel panel fixed to the seabed

via a floatable foundation.

The panel moves back and forth with the waves,

capturing the energy.

It's submerged in the depth of 15 meters

so it's protected from the extreme waves.

We generate electricity by capturing the movement

with hydraulic circuitry

in a machine room underneath the surface.

That hydraulic energy we turn to electricity

with hydraulic accumulators and hydraulic motors,

and also a generator.

The WaveRoller has survived large waves at sea

for over a year and delivered electricity

via an underwater cable to the grid in Portugal.

Meanwhile, the company has won a 2.5 million Euro grant

to work on an upgraded version of the WaveRoller,

aiming to increase the electricity generation capacity

to one megawatt.

The upscaled device would have a bigger panel,

two power takeoff units,

and improved software to control the energy production.

We have taken into use a wave prediction algorithm

that kind of tells us what kind of waves

are coming in to our device.

That gives us a few seconds to prepare

for capturing more energy

and the difference in that is significant.

Our future plans are to deliver technology

around the world.

So I'm hoping we can be working on delivering technology

to projects in Asia

and also in the American continent as well.

Meanwhile, Israeli company Eco Wave Power

is taking a different approach

to capturing the power of the ocean.

For the company's founder, Inna Braverman,

developing new sources of renewable energy

is a personal mission.

I was born in Ukraine in 1996

and two weeks after I was born,

the Chernobyl nuclear reactor exploded,

causing the largest in history nuclear disaster.

I was one of the babies that got hurt

from the negative effects of such explosion.

I had a respiratory arrest and a clinical death.

Luckily my mother, a nurse, approached my crib one time

and gave me mouth-to-mouth resuscitation

which saved my life.

I got a second chance in life

and decided to do something good with it.

Growing up, Inna wanted to be a politician

to positively change the world.

After working as a translator at a renewable energy company,

she decided to change paths.

Solar and wind energy were fully commercialized.

There were a lot of amazing technologies

implemented everywhere.

I saw that wave energy,

although it's an immense source of electricity,

the biggest companies in the world

are trying to develop wave energy with no success.

And there was kind of a race going on in the world

of who is the company that is going to develop

a viable wave energy solution first.

In 2011, the then 24-year-old Inna

co-founded Eco Wave Power.

Instead of installing devices offshore,

the company's devices are attached

to existing breakwaters, jetties and piers.

Our technology is very cost efficient,

especially in comparison to the offshore technologies,

because we don't need any ships, divers,

underwater mooring or cables.

We install on existing manmade structures

and all our expensive equipment, the generator,

the hydraulic conversion unit, the automation,

is located on land, just like a regular power station.

This is the Eco Wave Power conversion unit

that has been operating in Jaffa port since 2014 until 2020.

Here you can see how the technology works.

Basically the floaters are going up and down

and pushing the hydro cylinders

which transmit biodegradable fluid

into land-located accumulators.

A pressure is being built,

the higher the waves, the higher the pressure,

which is used to turn the hydro motor

which is turning the generators.

The whole system is controlled by a smart automation system

which you can see right here.

And in case of a coming storm,

the system automatically raises the floater

above the water level and keeps them in the upward position

until the storm passes.

The company has been operating

a 100-kilowatt grid-connected device in Gibraltar since 2016

which is enough to power 100 households.

Currently Inna and her team are working

on another 100-kilowatt project

at the port of Jaffa in Tel Aviv.

The project will be also the first time in the history

of Israel that wave energy will officially connect

to the electrical grid.

And our goal going forward is to expand it

to all suitable breakwaters in the city of Tel Aviv

and to supply a significant part

of the city's electricity needs.

Today, engineers and entrepreneurs

are still trying to crack wave energy.

Globally, only a few hundred kilowatts

of wave energy are deployed

compared with gigawatts of offshore wind.

But the field has come a long way in recent years,

and with the right engineering solutions

this new power source could eventually become competitive

with more mature renewables, like solar and wind.

I would have a lot more confidence in the success

of wave energy companies today

as opposed to, like, 20 years ago.

But in the next few years,

or maybe the next couple of decades,

it will be more likely to be used in remote locations,

like islands, that are otherwise dependent

on expensive diesel power,

or out at sea on gas decommissioning rigs,

or for powering underwater autonomous vehicles.

So definitely wave energy can compete

with other renewable energy sources,

but I personally believe that this is not a competition.

In order to have a 100% renewable energy friendly world,

we need all renewable energy sources to work together.