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Ocean currents and tides are an enormous amount of renewable energy just waiting to be harvested.
With tidal power we don't have to rely on building massive dams and waterways that disrupt
the environment in order to capture that power. Even though visions of underwater bladed turbines
might pop into your head, there’s some other technology that may surprise you ... like
an undulating membrane that produces electricity ... or an underwater kite. Gives the phrase,
"go fly a kite" a whole new meaning. Let's explore some interesting alternatives for
harnessing the power of tides that may be coming our way.
I’m Matt Ferrell ... welcome to Undecided
Believe it or not, harnessing the power of tides isn't something new. Back to the Middle
Ages, tide mills were mainly used to grind grains, and obviously there was no electricity
generation at all. In England, for example, there's a tide mill that dates back to 1170.
At that time, they would build a barrage across the opening of the basin so that one side
of the basin could fill while the tide was rising. Once the tide dropped, the water was
impounded before releasing it through a waterwheel. But it was only in the 19th century that utilizing
tides to produce electricity started to be considered.
In 1924, the US Federal Power Commission carried out a study for installing tidal power plants
in Maine and New Brunswick. Later, in 1956, Nova Scotia Light and Power of Halifax also
commissioned tidal power studies. But, it was the French who built the first tidal barrage
at commercial-scale in the Rance Estuary near St. Malo, France, in 1965. According to the
International Renewable Energy Agency (IRENA), since the 1960s, only five projects have been
developed commercially up to 2012. But, the number of full-scale projects and new technologies
that don't require a huge dam have advanced significantly over the past few years.
There are three main ways to harness the energy from tides and currents in a body of water:
tidal barrages, tidal fences, and tidal turbines.
Tidal barrages are very similar to hydroelectric dams. The barrage is attached to the seafloor,
and its top is just slightly above the level that the water hits during the highest tide.
During an incoming high tide, water flows over the turbines as the water goes up. Then,
the water flows back through the turbines as it becomes low tide, producing electricity.
Although tidal barrages are the most efficient way to harness tidal energy, they’re the
most costly and there are several concerns regarding their environmental impact. Tidal
barrages change the movement of water and fish into and out of estuaries, which can
impact some marine species. They can also change the structure of the coast and cause
erosion of dunes and other habitats.
Another type is tidal turbines, which is similar to a wind turbine ... but submerged. Since
water is denser than air, these turbines can generate more electricity than wind power
plants, but it also results in higher manufacturing costs since they need to withstand stronger
tides. They can also have a negative affect on marine life, causing the death of animals,
emitting noise, and taking up a considerable area of seabed.
The last type of tidal power is fences, which is like a hybrid between barrages and turbines,
but these turbines are positioned in a "fence-like" structure and spin like a turnstile. This
type of power plant produces electricity from tidal currents that push the turbine blades,
which are attached to a generator. They’re installed entirely underwater, and even though
they don't require large concrete structures like barrages, they can still have a negative
affect on marine life.
Although tidal power is a renewable, zero carbon emissions, predictable energy source
that can produce high power output, just like any other power source it has disadvantages.
Currently, there are limited installation sites, it's expensive, and as I’ve mentioned,
it can negatively impact the surrounding ecosystem. But, there are several companies researching
and developing new technologies to reduce those problems.
But before I get into that, if you want to be impressed by some creative problem-solving,
check out the audiobook Project Hail Mary by Andy Wier from Audible. Just like his book
The Martian, Project Hail Mary centers around one character using his knowledge of science
and creative thinking to solve some extremely complex challenges ... some very otherworldly
challenges. I talk a lot about technologies that can help combat climate change ... and
not to give anything away ... they have to deal with that exact issue in the book at
one point. It’s a gripping and inspiring book ... and if you’re like me, it’ll
probably grab you too.
I've been an Audible subscriber forever ... seriously. I listen to audiobooks when driving, walking
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If you want to listen to Project Hail Mary or any other audiobooks, go to audible.com/undecided
or text undecided to 500 500. Best part is that you can try Audible for free for 30 days.
Thanks to Audible and to all of you for supporting the channel. So getting back to the companies
researching and developing new technologies to reduce those problems.
The Scottish company Sustainable Marine has developed the PLAT-I (PLATform for Inshore
energy) technology, which is an innovative floating tidal energy system. Their PLAT-I
6.40 is equipped with six in-stream turbines that can generate up to 70 kW, which means
the entire platform can deliver 420 kW of power, and its modular design allows it to
be shipped to any part of the globe with easy assembly on site. An onboard transformer steps
up the voltage before it flows out of the platform towards the shore station through
a subsea cable.
The company is going to be testing the platform in the Bay of Fundy’s Grand Passage (FORCE)
site as part of the first phase of the Pempa'q In-Stream Tidal Energy Project, which will
produce up to 9MW of electricity to the Nova Scotia grid. The goal is to reduce 17,000
tons of CO2 equivalents annually and power approximately 3,000 homes.
A similar approach has been developed by Orbital Marine Power, which launched its 2MW floating
tidal turbine, the Orbital O2, in April 2021. This platform has twin 20-meter (65.6-ft)
rotors on the ends of 18-meter-long (60-ft) articulating arms, which means sweeping more
than 600 square meters (6,460 sq ft) of area below the surface. Anchors can moor it in
powerful tidal streams or river currents, and the underwater blades harness the energy
from tides. The platform can generate clean, predictable electricity to meet the demand
of around 2,000 UK homes and offset approximately 2,200 tons of CO2 equivalent production per
year. The most interesting part is that it can be launched like a ship and float out
to its location to be moored, commissioned and connected to the grid.
This 680-tonne power house was assembled at the Port of Dundee for past 18 months. Orbital
Marine Power chief executive Andrew Scott said:
"We've been developing this technology here in the UK for over 15 years."
Orbital estimates an LCOE for its first 2MW O2 turbine of under £200/MWh. This isn't
far from government investment contracts supporting over 3 GW of installed offshore wind capacity
in U.K. waters, which range from £165/MWh to £180/MWh.
The turbine arrived in Orkney Waters on April 24 and is now being prepared for installation
at the European Marine Energy Centre (EMEC). This the third Orbital turbine that EMEC will
be testing, but the O2 is first one that is a commercial demonstrator plant. If this works
out, they’ll be moving to commercial sales of the technology.
Orbital claims the design as "the most powerful tidal turbine in the world", but it turns
out that another particular design can also produce a great amount of power.
The undulating membrane produced by EEL energy can provide up to 5MW of clean, renewable
energy. It’s something that kind of looks like a whales tail swimming underwater. In
this case, energy is converted all over the membrane surface. It undulates as fluid flows
through it, generating a periodic motion converted into electricity by an electromechanical system.
It also uses a monitoring loop to boost energy conversion as the flow and power change during
operation.
The benefits of this design are a low drag force, reduced dimensions compared to the
power it can deliver, and it automatically orientates itself and is able to capture 100%
of the current. And the minimum area required for installation is 10 times smaller than
wind turbines. One downside, it sounds like it’s still a ways out for production. Prototype
tests for industrial production were scheduled for 2020, but there’s no new information.
Jumping over to another exciting alternative, what about a kite that generates electricity
by flying underwater? Yep ... sounds a little weird, but it's real. The concept of the Deep
Green ocean energy power plant, which was patented by Minesto, is something that I don’t
think most people would have come up with. Unlike any of the other tidal turbines, this
one has wings that push the turbine through the water in a figure eight-shaped pattern,
covering a large area at a relative speed that is several times faster than the actual
speed of the underwater current. This makes it a great alternative to harness low-flow
tidal streams and ocean currents ... but how does it actually work?
The wing uses the hydrodynamic lifting force created by the underwater current to move
the kite. An onboard control system and rudders steer the kite autonomously in that figure
eight trajectory, pushing the turbine through the water. Since the power produced by this
unusual power plant has a cubic relationship to its velocity, speeding up the turbine makes
the generated electricity several hundred times greater compared to if it was stationary.
The turbine is connected to a generator that provides electricity through a power cable
in the tether. Then, a seabed power cable transfers the electricity to the onshore station.
The company has two product lines to provide some flexibility. The Deep Green Microgrid
focuses on project developers, island economies, and aquaculture developers. It’s geared
more towards remote users. It has a rated power from 50 to 250 KW, weighs between 1
to 3 tons with wings that range between 4 to 6 meters, and the depth of installation
is lower than 60 meters. Minesto also offers the Deep Green Utility, which focuses on customers
like utilities, project developers, and power producers. This is a more powerful tidal power
plant that can produce from 500 KW to 3 MW, and weighs between 10 to 35 tons, with wings
between 12 to 24 meters, and is also installed deeper than 60 meters.
According to the company, Deep Green is the only known technology to cost-effectively
produce electricity at sites with speeds between 1.2–2.4 meters per second and depths of
more than 60 meters. And it’s small size is a potential advantage, since it’s up
to 15 times less per MW than competing technologies.
In October 2020, Minesto installed its first 100kW DG100 tidal kite system in Vestmannasund,
a strait in the North West part of Faroe Islands. Minesto has been granted public funding totaling
approximately €3.5 million by the EU’s EIC Accelerator and the Swedish Energy Agency
for the development of the project. The system has been delivering power to the grid since
December 2020.
They’ve also started to develop and build the Holyhead Deep site, in North Wales. Once
fully installed, a 10MW Deep Green array will produce local and clean electricity with the
equivalent of more than 8,000 Welsh households. They plan to increase the site to deliver
80MW, which would increase that figure to almost 70,000 households.
But how much does it cost? According to the company, Minesto’s LCOE will fall to €100/MWh
after 100MW of installed capacity in tidal streams.
Although the market of tidal energy is still small compared other renewables, the global
market for Wave and Tidal Energy was estimated at US$542.8 Million in 2020, and it's projected
to reach US$5.1 Billion by 2027, which is a growth rate of 37.7% (CAGR). This growth
can come with the technology advancement, government grants, as well as green policies.
For example, in September 2020, Canada announced a $9.4-million investment in four tidal energy
projects to install green energy technologies to the Atlantic region.
The development of tidal power can also contribute to other carbon-free technologies. For example,
electrical vehicles on the island of Yell in Shetland, Scotland, can now be charged
entirely by Nova Innovation's tidal turbines. These turbines have been powering homes and
businesses in Shetland for more than five years, and now the island’s vehicles can
be powered purely by the tide.
Although tidal energy has been stepping up slowly compared to solar and wind, it's evident
that this power source can have great potential. A kite that generates power from low-flow
tides, an undulating membrane that can produce up to 5MW, and huge tidal power platforms
are just a few examples of what could come.
So what do you think? Do you think any of these will catch on? And any other tidal technologies
that I should have covered? Jump into the comments and let me know. If you liked this
video be sure to check out one of the ones I have linked right here. Be sure to subscribe
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and a big welcome to new producer, Gray Hilliard. And of course thanks to all of you for watching.
I’ll see you in the next one.