E-Island
(Energy, Economy, Environment)
Introduction to the project
The electrical output of wind turbines is intermittent. Sometimes there is little to no wind and wind
turbines only start to deliver power from wind force 2-3. At wind force 6 they deliver at full output
and that continues until around wind force 10. A wind turbine produces twice as much in a typical
winter month than in a typical summer month. Furthermore, when the wind force drops, a wind
turbine can decrease from full output to almost nothing in just a few hours.
The electrical output of solar panels (photovoltaic cells) is intermittent as well. The sun intensity is
higher in Summer than in Winter, may vary substantially during the day and is zero during the night.
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This variation in energy production from sun and wind comes on top of the usual variation in daily
electricity demand.
Energy storage offers a very effective way to balance electricity demand and supply and is used by all
players in the energy sector, being generators, grid operators and consumers.
For storage of small amounts of electrical energy, batteries may offer a good solution. However,
when big amounts of energy have to be stored, Pumped Hydro Storage (PHS) is currently the only
realistic option. PHS accounts for about 99% of the worldwide storage capacity and it has been in
practice for more than 100 years. It is the most competitive storage option, has a very high
operational reliability and unmatched safety records.
The major constraints to a further extension of the current PHS capacity are a lack of suitable
locations and a growing water scarcity.
Both issues, space and water, are solved by DEME’s Offshore Energy Storage Island project, further
called the “E-Island” project. This E-Island is an innovative PHS site, located at sea and working with
sea water. It is constructed with locally available materials from the sea bed and is very flexibly
scalable. It can be connected to the grid but also to offshore generation units such as offshore wind
farms, tidal lagoons, etc.
Governments and institutions have already started to adopt the idea.
The Belgian government created 2 special zones (figure 1) for the construction of E-Island sites in its
Marine Spatial Plan (Royal Decrees of May 8th, 2014 and of March 20th, 2014).
The project was also included in the Ten Year Network Development Plan 2016 (TYNDP 2016), i.e. the
European network development plan, ordered by the European legislator and drafted by ENTSO-E
(European Network of Transmission System Operators – Electricity). Projects from TYNDP 2016 may
receive the European status of Project of Common Interest (PCI).
The project was also listed for support from the Plan Juncker (EFSI) of the European Commission.
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2 zones for energy
storage.
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Figure 1 – Excerpt from the Belgian Marine Spatial Plan
Construction & Operation
Construction
A hole is dredged in the sea bed. The (sandy) material extracted from the sea bed is put around the
hole. As such, a ring-shaped dyke is built around the hole, creating a reservoir isolated from the
surrounding sea. Tunnels in the dyke connect the water from the reservoir to the surrounding sea. In
these tunnels, hydraulic machines (pumps/turbines) are installed.
Operation
In case of excess power in the grid, water is pumped out of the reservoir into the sea. As a result, the
water level in the E-Island reservoir becomes lower than the surrounding sea water level. (fig. 2a) In
the case of a power shortage, electricity is generated by letting water flow back from the North Sea
into the reservoir, passing through hydraulic turbines. (fig. 2b)
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Fig. 2a - Storing electricity by pumping water from the reservoir to the sea
Fig. 2b - Generating electricity by letting sea water flow into the reservoir through turbines
Fig. 3 - Top view of an E-ISLAND
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Figure 3 gives a top view of an arbitrarily chosen E-Island design. The length and width dimensions
are typically in the kilometres range, the depth of the reservoir is typically a few tens of metres.
Power and energy storage capacity
The power capacity (expressed in Megawatts, MW) of the E-Island is freely scalable by increasing or
reducing the number of hydraulic machines (pumps/turbines) and will typically be many hundreds to
a few thousands of Megawatts.
The energy storage capacity (expressed in MegaWatthours, MWh) of the E-Island is freely scalable by
increasing or reducing the depth and/or the surface of the reservoir and will typically be many
thousands to tens of thousands of MegaWatthours.
Location and seaview
E-Island can be located anywhere in the sea at water depths of maximum a few tens of meters. As
such, E-Island sites will be typically located a few kilometres off the coast. Normally, a safety
perimeter of e.g. 500 metres will be foreseen around the island. The height of the dyke is comparable
to the height of harbour dams. The dyke can be designed as a soft, natural sea defence.
Figure 4 gives a provisional representation of an E-Island, located approximately 5 kilometres of the
coast, from the perspective of a person looking from the beach towards the sea horizon at medium
tide.
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Fig. 4 - Representation of E-Island seen from the beach.
Environmental potential
As the E-Island is typically located a few kilometres off the coast, it offers environmental advantages
such as high water quality (remote enough from coastal pollution) and inaccessibility for humans and
predators like rats. As such, the E-Island offers tremendous opportunities to all kinds of (often
endangered) marine life such as birds, seals and fish.
Economic potential
The economic potential of the E-Island stretches far beyond the energy storage function. Other
conceivable economic functions are e.g. (non-exhaustive listing):
Renewable Energy (RE) generation
Wind mills can be built on the E-Island, thus combining the advantages of onshore (lower
investment) and offshore (better wind conditions) wind farms and as such leading to wind energy
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with high financial returns.
Floating solar panels can be installed in the reservoir, leading to higher yields than on-shore solar
panels because of the better sun conditions at sea, the higher efficiency of the solar cells due to the
cooling effect of the water and the reflection of the sun light at the water surface.
Also special infrastructures for generation of wave and tidal energy are conceivable and installable
on the island.
Fish Farming / Aquaculture
Due to its location a few kilometres off the coast, the conditions for fish farming and/or aquaculture
(e.g. in the reservoir), seem ideal: no pollution from coastal waters, nevertheless close enough for a
profitable logistical operation and daily in- and outflow of fresh sea water, rich in nutrients.
Coastal Defence
The rising sea level leads to more violent waves and storms. An E-Island, or, even better, a belt of
islands, situated a few kilometres off the coast, is the ideal way to break the waves before they
devastatingly hit the coast. As such, the E-Island fights the causes (by enabling CO2-emission
reduction through allowing massive integration of Renewable Energy Sources), as well as the
consequences (the rising sea level) of climate change.
E-Island as a launching platform for Blue Growth
Seas and oceans are drivers for the European economy and have great potential for innovation and
growth.“Blue Growth” stands for a new concept of self-sustaining marine economic development in
harmony with the environment, fuelled by renewable energy generation.
Islands such as E-Island can serve as the launching platform for this exciting and future-oriented
societal development.
Added value
The E-Island project offers a range of additional benefits:
Attribute
•
CO²
•
EU Climate
objectives
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Added value
E-Island releases no CO² during operation and is therefore a totally
environmentally friendly concept. It is a crucial part in the supply
chain of green/sustainable energy: production, transmission &
distribution, consumption and storage.
E-Island promotes sustainable energy by facilitating the efficient
integration of sustainable energy into the existing network. The
project plays a role in the “Roadmap for moving to a competitive lowcarbon economy in 2050” from the European Commission, imposing a
reduction in CO² for the energy sector of 93-98% by 2050.
•
Technology
•
No “Must run”
•
Innovation
•
Export
•
Nature
•
Environmental
compensation
Coastal safety
•
•
•
•
•
•
Building with
nature
Price stability
Large-scale energy
storage
Space
European energy
policy
Proven technology: the different types of technology that will be
implemented for E-Island have already demonstrated their value and
reliability in other applications.
To deliver system services a gas-fired power plant (“STEG” type) needs
to operate continuously at a minimum of 50-60% of its maximum
capacity. This phenomenon is called “must run” and causes
considerable additional CO2 emissions and costs. With E-Island this is
not the case.
The plan, construction and follow-up of this project create expertise
and clustering of know-how for European businesses.
A unique project of this kind is of international relevance:
− Balancing sustainable energy is a worldwide issue today;
− It is a unique balancing concept and plan;
− It is a unique offshore infrastructure project.
The island will replace the existing sea bed with a dynamic beach
habitat with considerable ecological value (incl. nesting area for
birds).
The site offers considerable opportunities for direct environmental
compensation and the development of a coastal ecosystem.
The island will offer additional protection for the local coast against
heavy storms and sea level rising.
E-Island will be made in harmony with natural processes and largely
with natural materials.
The project offers great price stability over the long term as the
energy delivered is not dependent on fuel prices and CO2 taxes.
By allowing large quantities of energy to be stored E-Island facilitates
the move towards a green energy supply.
There would hardly be room for a large-scale energy storage unit like
E-Island on land. The offshore location solves this problem.
Furthermore, at sea there is water available for the actuator and sand
for the construction of E-Island. Finally, when located closely to
renewable energy sources, such as offshore wind parks, the
transmission across the electricity network is reduced and the
capacity is better used.
E-Island supports and safeguards the decision to make sustainable
energy an important part of the portfolio within a European clean
energy policy. Being located in the European control area and by
ensuring more security in supply it will increase Europe’s energy
independency.
Contact:
[email protected]
[email protected]
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