Advocates of floating offshore
wind platforms say they are cheaper to run and install, less disruptive
to sea life, and have greater output than near-shore alternatives. Image
credit – WindFloat
As wind turbines become
increasingly familiar sights along shorelines, developers of offshore
floating platforms, which harness the powerful winds further out to sea,
are seeking to establish their technologies as a major viable source of
Bottom-fixed offshore wind turbines – with
foundations in the seabed – face depth constraints and can only be used
in relatively shallow coastal waters.
Floating offshore platforms can instead be
built and installed in almost any marine environment. They are cheaper
to run and install, more environmentally friendly to sea life, and have
greater output, according to those behind the technologies.
What’s more, positioning the turbines well offshore exposes them to the generating power of stronger winds.
‘The further you get from the coast, the
more wind you normally get,’ said José Pinheiro, project director of
energy company EDP Renewables.
The energy company is part of the WindPlus
consortium, set up by Energias de Portugal, REPSOL and Principle Power
Inc., which has secured a €60 million loan from the European Investment
Bank under the InnovFin Energy Demonstration Projects instrument. This
will allow it to scale up a pilot demonstration project, WindFloat, and take it out to deeper water.
‘With this WindFloat technology you have
the ability to harness the wind where you have it most,’ Pinheiro said,
adding that this meant there were many more potential sites than are
available for bottom-fixed wind power.
A 2017 study
showed that wind power generation over some ocean areas can exceed
power generation on land by a factor of three or more. However, the
technology is mostly still at testing phase as the bases of floating
turbines need to be engineered differently from their near-shore
Pinheiro said the new financing for the
WindFloat Atlantic project, to be installed at a site off the northern
coast of Portugal, is crucial to showing the commercial viability of the
technology. It is also a long-term test of its technical attributes in
The three-column, semi-submersible
platform will be mounted with an 8.4 megawatt turbine, floating in
waters 85 to 95 metres deep. It is anchored at three points, as is
common for oil and gas production facilities in deep water.
‘Scaling up can reduce the unit costs a
lot, so we are really contributing to showing that offshore floating can
achieve the targets that have been set for it,’ Pinheiro said. ‘It can
also show the convergence of the technology with business opportunities
around the globe.’
WindFloat Atlantic seeks to take advantage
of onshore construction and assembly to reduce costs, and it is not
alone in choosing that path.
‘The further you get from the coast, the more wind you normally get.’
José Pinheiro, project director, EDP Renewables
Ocean Flow Energy, based in northeast England, leads the FLOWSPA
project to develop a novel offshore wind support platform – Starfloat –
based on two well-known platform systems used in offshore oil and gas
Project coordinator Graeme Mackie says
their design consists of a floating spar, a structure used in deep water
oil production that looks ‘like a tower that floats (vertically) in the
sea’ which is moored by chains and anchors in the seabed.
Normally, spars have to be immersed in
extremely deep water, so to reduce this requirement, the team has added a
semi-submerged buoyancy ‘collar’ made up of several floats that
surround the neck of the spar at the waterline and keep it raised. This
hybrid satisfies stability and motion demands even in harsh
FLOWSPA engineers devised an assembly
strategy that allows the platform to be readily built at existing
onshore shipyards, and enlists the local economies, which have been in
decline in many parts of the world. The turbine is then towed out to
The simplicity of the design, the use of
existing shipbuilding facilities and nearby assembly rather than the
on-site construction of fixed installations, as well as the cheaper
deployment of the complete platform, all contribute to reducing costs,
Their target is to generate electricity at
about 60 euros per megawatt-hour – competitive with current inshore
wind farms – for a large-scale facility.
‘(This) is achievable if you build these devices in serious production,’ Mackie added.
To get deep sea wind platforms up and running quickly, the Spanish SATH
project has taken a different approach to its design, which comprises a
twin hull with submerged plates, and is built mostly from concrete,
rather than steel.
It is built and assembled onshore and then
towed to its final position and hooked up – at a single point – to
pre-installed mooring chains.
‘It can rotate around, so it is always
facing the wind,’ said David Carrascosa, chief technology officer at
Saitec Offshore Technologies, coordinator of the project. ‘The
mechanical connection (for the mooring point) is through a bearing, and
the electrical connection through a rotating electrical swivel.’
Having a single connection point and power
transmission cables out at sea allow the platform to be quickly
connected to the mooring infrastructure.
Being able to construct onshore and
rapidly install the platforms mean that SATH bypasses the costly weather
problems that can disrupt more time-consuming and complicated
Carrascosa said the platform’s materials
and construction approach, using local resources, means it can be
mass-produced at sites around the world, close to where the wind
turbines will be deployed.
With lower capital and operating expenses
come major cost savings over the lifetime of the platform, particularly
in depths greater than about 50 metres.
‘By making offshore floating wind
production more competitive, we can see a big market ahead, and that is a
goal for all of us,’ Carrascosa said.
Despite the projects’ different approaches
to engineering and materials, all say they have embraced methods of
construction and installation that reduce their impact on sea life,
compared to fixed installations.
With much of the construction and assembly
done onshore or nearby, the projects can minimise the noise levels that
researchers cite as a major problem for marine mammals. Carrascosa said
that disruption is also reduced by avoiding the need to embed major
structures in the seabed.
‘People (in the industry) are really aware
of these issues affecting the mammals and that is something you can
avoid by using floating solutions,’ he added.
The research in this article was funded by the EU. If you liked this article, please consider sharing it on social media.
Innovative European companies can often
fail to get funding to build the large-scale demonstration projects
needed to develop their ideas into commercially viable technologies or
services. This means they can fall into the so-called valley of death
between innovation and commercialisation.
To bridge this gap and support the
implementation of the EU’s Strategic Energy Technology Plan, the
European Commission and the European Investment Bank created the InnovFin Energy Demonstration Projects facility.
Up to EUR 800 million is available to help companies demonstrate the
commercial viability of their first-of-a-kind projects in the fields of
renewable energy, energy storage, smart grids, and carbon capture
utilisation and storage.
The Windfloat loan is the fifth such deal
and, at €60 million, the largest so far. Previous loans include €52.5
million for the manufacturing of battery cells for use in transport,
energy storage and industry, €30 million for a gasification plant to
convert wood residues and industrial waste into electricity and heat,
€15 million to set up a manufacturing line for new and highly-efficient
photovoltaic technology, and €10 million to build a demonstration unit
that converts wave energy into electrical power.
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