You might remember I bought this wind turbine a few weeks ago for one of my previous videos.
It's been upon the bookcase since then, but I thought it might come in handy again today.
You see while onshore wind power is something we've all become quite used to seeing in most
parts of the world, offshore wind actually represents the biggest opportunity for generating
massive quantities of power for our electricity grids. That's because winds are stronger and
steadier at sea than they are on land, so offshore wind delivers a higher power per unit area
than onshore wind. Winds out in the open sea often blow during the afternoon too which means the
offshore turbines can provide very useful power at a peak time of the day. We've already got loads of
offshore wind farms here in the UK and around the coast of some other European countries,
but they're all located in relatively shallow waters, only about 25 to 30 metres deep where
everything can be nicely bolted down to the seabed. Now though the race is on to develop
wind turbines that can be towed out into the deep ocean where the winds are even stronger and more
consistent. The only snag is that those open ocean waters are far too deep for a tower to be extended
down and bolted to the bottom. So apparently these turbines are just going to float...
So how they're going to do that then
Hello and welcome to Just Have a Think. The first ever offshore wind farm was opened
at Vinderby in Denmark in 1991. It had a power generating capacity of 5 megawatts
providing for the annual electricity consumption of just over 2 000 Danish households.
In 2013 a comprehensive review of offshore wind concluded that the benefits to cost ratio
was not as good as the industry had suggested, and that the offshore wind market "doesn't look
as if it's going to be big". The review pointed to what it saw as critical disadvantages of offshore
installations, including difficulty of access and harsher conditions like higher humidity
and saltwater corrosion and oxidation which tend to increase maintenance and repair costs and in
general make every aspect of installation and operation more difficult and dangerous,
and therefore more time consuming and expensive than sites on land. Despite that pessimism,
the offshore wind market has grown strongly. There are now 162 offshore wind farms around the world,
with a combined generating capacity of nearly 33 gigawatts. That's more than 6 000 times the size
of that very first Danish installation. Just last year another 15 new offshore wind farms went into
operation with a combined capacity of 5.2 gigawatts. The majority of those installations
are located in Europe and China, but the United States is now starting to get into the market too.
President Biden has pledged to deploy 30 gigawatts of offshore wind power within the next decade,
and the first major project, called Vineyard Wind 1 - an 800 megawatt farm off the coast of
Massachusetts, was announced in May 2021. All these installations stay close to the shoreline
where waters are shallow and the distances to large urban connections are relatively small.
The technology is now fairly mature and there's 40 years of industry knowledge
and experience in the field bringing efficiencies and economies of scale that just weren't foreseen
in that 2013 review paper. So why rock the boat, quite literally, and push out into deep waters
where the whole operation takes on far greater risk and expense? Well, here in Europe wind farm
developers are rapidly consuming the low-hanging fruit of easily accessible near-shore shallow
water locations that can be exploited without too much objection from local fishing fleets,
conservation groups and coastal residents who complain about having their views spoiled.
So going further out to sea is becoming an increasingly urgent consideration.
Installing turbines in the open sea also presents fewer risks for other species that we share the
planet with too. Krag Peterson, a wildlife ecologist at Aarhus University in Denmark,
says birds like eagles, ducks, griffins, stalks and gannets can collide with the mammoth blades
of offshore rigs, but the density of turbines in deep sea wind arrays is far lower and bird flights
are more thinly distributed, so the potential impact on their population is greatly reduced. Up
off the windswept northern coast of Scotland, five towering turbines -each standing 174 meters tall -
make up a renewable energy project called Highwind Scotland, a floating deep water demonstration wind
farm that's been generating enough electricity for more than 20 000 homes since 2017.
The giant masts and turbines float in waters more than 90 metres deep, sitting in buoyant concrete
and steel keels that enable them to stand upright on the water a bit like a (UK) buoy or (US) buoy.
The cylindrical bases of the turbines weigh 10,000 tons and are held in place with three
taught mooring cables attached to anchors which lie on the sea floor. Each cable has
a 60 ton weight hanging from its midpoint to provide additional tension. Control software
on board constantly monitors the operation of the wind turbine and alters the pitch of the blades
to effectively dampen the motion of the tower and maximize production. So far the high wind
demo has functioned well in all the wind and wave conditions the North Sea has been able to throw at
it over the past four years, including hurricane Ophelia in 2017, and other harsh winter storms
bringing hundred mile an hour winds and eight meter high waves. Just a few miles away, off the
coast of Aberdeen, the world's largest floating wind farm received its fifth and final turbine in
July 2021 and it will be fully operational at the start of 2022. The six turbines at the Kincardine
installation are the largest machines ever to have been installed onto floating platforms and they'll
have a generating capacity of 50 megawatts - enough power to run almost 60,000 Scottish homes.
The area beyond reach of conventional offshore turbines makes up 80% of the world's maritime
waters and the mind-boggling amount of energy available out in the wilds of the open ocean
is proving to be just a bit too tempting for turbine makers to ignore. Over in the United
States, according to the National Renewable Energy Laboratory or NREL, the total potential production
capacity of offshore wind farms there is nearly double the entire US annual power consumption
of four thousand terawatt hours per year. Forty-two percent of that will most likely come
from fixed-base offshore turbines in shallow waters off the eastern seaboard like those being
developed at Vineyard Wind 1, but it's a very different story on the other side of the country
where the continental shelf drops off very rapidly and you're into deep water
within only a few miles of the shore. The remaining 58% of US offshore potential power is,
according to NREL, therefore locked up in these deep water ocean areas. And that's something that
the American behemoth General Electric, or GE, are fully engaged in trying to liberate.
This guy is Rogier Blom. He's the Senior Principal Engineer for Controls and Optimization
at GE global research in Niskayuna, New York. Rogier and his team have designed a 12 megawatt
floating version of the Haliade X, the most powerful offshore wind turbine in the world.
These colossal feats of engineering will have 260 meter tall turbines with a rotor diameter of 220
meters. Each turbine will be capable of generating 67 gigawatt hours of electricity a year. That's
enough power to run 16 000 households - just from a single turbine! The system being developed by GE
involves bolting the towers to floating platforms which the development team refer to as floaters.
Which is unfortunate! But those floaters are essential to carry the turbine's tremendous weight
and respond to the constant motion of the seas and wind. As Blom explains in this GE article
from May 2021 "building a floating wind turbine is like putting a bus on a tall pole and keeping
it upright floating and steady no matter what conditions it faces". Blom's plan is for the
floating platforms to be tethered to the ocean floor by what he calls actuated tension legs.
Active tendons will allow the turbines to ride big waves and reduce the magnitude
of the overall mechanical load. GE's concept is based on what's called control co-design,
in which the entire system - the turbine and platform as well as the control algorithms - are
all designed in tandem, and that avoids the need to put additional mass into the system
to withstand high winds and waves - something that adds huge cost to the construction of floating oil
rigs for example. That cost reduction results in a lower levelized cost of energy or LCOE,
which is the standard metric that the energy industry uses to compare different technologies.
Some renewable energy experts do still remain skeptical though that the high cost of floating
offshore wind turbines will come down far enough to rival other clean energy technologies.
Currently the electricity they generate is often almost twice as expensive as near shore wind
turbines and three times that of land-based wind turbines. It is still maritime engineering after
all, which makes it comparatively expensive to build, deploy and maintain, with shorter
operational life spans as a result of the corrosive nature of the marine environment that
they sit in. But advocates of floating wind point out that the costs of onshore and near-shore wind
energy have continuously dropped as efficiency and economy of scales have improved over time,
and those trends are likely to be the same for floating wind turbines too. They argue that while
some of the mechanical details are still being tweaked, the basic technology of floating wind
is sound. After all, they say, the oil and gas industry has been using similar marine know-how
for decades on their floating platforms in some of the harshest marine environments on the planet.
We are still some years away from a world with hundreds of deep sea floating wind turbines
providing huge quantities of renewable energy to major populations all over the planet,
and the rollout of these facilities at the sort of scale required will certainly call for big backing
from governments and corporate investors who will of course need to be convinced of the long-term
capital returns. As Frank Adam, an expert on wind energy technology at Rostock University
points out in this BBC interview, "it's easy to produce one or half a dozen floating turbines,
but 10 or 20 or 100? That's another story. This requires supply chains, shipyards and ports
that can handle such enormous structures, and factories for serial fabrication". Nevertheless,
despite these challenges, the potential of this kind of renewable energy generation
remains an attractive proposition and the amount of energy that could be produced would be globally
transformational. The International Energy Agency projects that offshore wind power alone
could eventually meet the entire electricity needs of Europe, the US and Japan many times over. And
if China does dive into offshore wind like they have done with other renewable energy technologies
then it may just provide yet another route for them to slow down or even reverse their
currently unsustainable schedule of opening the equivalent of a new coal mine every week.
If you've got news or views on this one, or if you have direct experience in the industry that you'd
like to share, then jump down to the comments section below and leave your thoughts there.
That's it for this week though. A big thank you as always
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