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We make wave power competitive

Wavepiston's non intrusive, simple, robust and low-cost solution for harvesting the energy of the oceans.

Competitive Renewable Energy

Levelised cost of energy is estimated to be best in market

Broad, Conceptual Patent

Patent on the force cancellation principle is issued in countries around the world

Simple, Robust, Standard,

The technology is assembled using rugged components and standard offshore technologies.

“For WECs, the key to successful commercialization is the right combination of low cost, good conversion efficiency, and survivability. Wavepiston, because of its unique design is poised to offer a breakthrough in all three categories.”
- C.A. Goudey & Associates
“…Wavepiston have come up with what is in my opinion likely to be the first commercial viable wave energy harvesting device.”
Julian Smith, CENG MRINA. Naval Architect and Structural Engineer

Technology


In the ocean a chain of energy collectors is stretched between two anchored buoys.


When waves roll along the Energy collectors, plates are moved back and forth.


The moving plates pump seawater into a pipe.


The pipe leads the pressurised water to a turbine and/or a reverse osmosis system in a dry and easily accessible location for energy conversion.







Wavepiston module

The key benefits of this concept are:


The costs are massively reduced due to the light flexible structure, optimized mooring and modular design.


Simplicity and robustness is ensured by the use of standard offshore technologies.


The fully submerged system and nonpolluting materials ensure a non-intrusive technology.
Fullstring

 

Wave power challenges (Click figure for details)

To evaluate a wave power device it is important to understand the major challenges in harvesting wave energy.

As the figure shows wave power is much more than just converting the movement of waves.

FORCES - Wave energy is refined wind energy. When a storm has affected the ocean for days, the energy in a wave can be up to 1 MW/m wave width. These large forces will drive the cost of structure and mooring through the roof if the concept does not have a solution for this.

POWER CONNECTION - Power cables and connections at sea are very expensive. For Offshore wind power farms the internal power connection is 5% of the total cost and grid connection is 10%

LOGISTICS - Large structures are expensive to transport and deploy. A typical deployment vessel costs 50.000€ per day. That also goes for the days with bad weather and the vessel on standby.

MAINTENANCE & SURVIVABILITY - Seawater, cyclic forces and marine growth are a tough combination for mechanical structures. The correct choice of design and material is essential to build a low maintenance system.

How we handle the forces of the ocean

The Wavepiston concept captures the surge energy with vertical energy collectors (ECs) distributed on a horizontal string.

The defining and new feature of this concept over existing concepts is that many ECs are attached to

the same structure. The innovative aspect is that the mooring costs are reduced substantially, since many ECs can be moored using only two anchors.

The concept does, however, have another even more important feature: Due to the length of the string, and the oscillating nature of waves, ECs along the string will be subjected to forces in opposing directions. This is illustrated by men, all pulling a rope in different directions.

Force Cancellation

Although the situation for a single man is not affected by this situation, the net result of pulling in different directions is that comparatively small forces can anchor the rope. Like the men in the illustration the ECs are subjected to shifting wave forces in at any given time, hence resulting in a sharp decrease in the required anchor force.

This enables a slim, light and extremely cost-effective structure. Advanced simulations and tests by University of Aalborg (AAU) have proven that with more than 20 ECs connected in this way, the mooring needs are reduced to 1/10 in comparison with ECs moored individually, cutting the costs dramatically.

Mooring 10%

Structure 10%

Energy 100%


The idea of connecting several vertical ECs to a structure is issued as a patent in large parts of the world and marketed as “Force Cancellation”. Force cancellation does not affect the energy conversion.

How we handle storms

To optimise efficiency, cost and lifetime, a reduction of loads in storms is needed. We have chosen a double route strategy for proper redundancy:

1. Descending the system (in locations with high wave power density / large extremes): The string with the ECs is placed near the surface where the energy is most dense. During storms, we can flood parts of the system to bring the EC’s to greater depths and calmer waters (illustrated below) until the storm has passed.

Storm

2. Collapsing plates: If the plates hit the end stop a flipping mechanism makes the plates collapse taking the loads of the plates. When the loads decrease the plates flip back into position. This idea is very similar to the pitching of the wind turbines blades in high winds to reduce the loads.

Collapsing plates
 
Collapsing plates

The extreme wave conditions are present in less than 1 % of the year. Designing for energy absorption in these short periods will drive up the cost of any system, and most likely lower the average power output. Hence a load control system is a necessity. The figure on the left shows the reduction of critical stresses when the plate is flipped.

How we avoid subsea power connections

Electric connections and power take of systems in water are notorious for being fragile and expensive.

For this reason, hydraulic and pneumatic power lines are always chosen over electrical power lines in off-shore structures.

Drawing on the experience from the offshore industry, the mechanical movement of the ECs is converted into pressurised water by hydraulic pumps.

Wavepiston module

The pressurised water is led to a turbine station and/or reverse osmosis system for desalination. This is placed on-shore for near-shore installations. For off-shore installations it will be placed on either a spar or a barge.

A commercial system will consist of many strings all leading the pressurised water to one turbine/reverse osmosis station.

Wavepiston module

Efficiency: turbine 80%

Efficiency: pipes/valves 94%

How we handle logistics

The low weight of a Wavepiston system enables the use of small vessels when deploying.

A Wavepiston system can be viewed as two parts; the main structure and the energy collectors.

The main structure consists of well proven standard offshore components such as mooring rope, chain and anchors. These are delivered by well-respected international companies. The energy collectors, which are the key components in a Wavepiston system, are modular. The nominal energy production of a single (full scale) EC will be in the range of 10kW. A commercial Wavepiston system will consists of hundreds to thousands of energy collectors. The large number of identical, simple, components enables, in the commercial situation, simple logistics and fully automated production. This strongly affects the production cost, but also speeds op optimization of the components.

Modules packed

The EC’s are designed to be fitted into 40 foot containers. The assembly process on site can be carried out using local workforce with just brief training, due to the simple mechanical structure. The simplicity also allows for maintenance with relatively little training required.

Packed container

// Will the first plates not take the energy in the waves, leaving little or nothing to the next?    No - each plate has an efficiency of 2% -13% depending on wave size. Energy passing beside or below the plates will spread and make up for the lost energy. The loss from one plate to the next is only 1% - 2%.

// Will the system produce energy when waves come from the side?   Yes and no - If waves come at an angle of 90° the system will not produce any energy. Test made with waves from different angels show an efficiency of 80% when the angle is 30°. The concept is designed to lay perpendicular to the coast thus waves directly from the side are not very big.

// Can the system handle sideways current?    Sideways current can be an issue. We aim to do the first test in an area without heavy current. We believe 1- 1.5 knots won’t be a problem as we have made calculations on that. The test will reveal if we must have an extra mooring point at the middle of the string to handle currents above 2 knots.

// The system looks very thin; will it not break during storms?   No - The best way to survive in the dynamic forces of the sea is being flexible. Static structures will experience forces that are much higher than flexible structures. The use of slack mooring gives that flexibility. The weight of the anchor chain works as a spring when forces get to high.
The use of slack mooring and hinged connections give that flexibility. The weight of the anchor chain works as a spring when forces get too high.

// Will marine growth damage the system?     Biofouling has not been an issue in our tests so far. Pipe and pumps are opaque hence marine growth will only happen on external surfaces of the Wavepiston system. Our tests show that weight neutral growth is not affecting the function of the plates and we have mitigated extensive growths like mussels by covering the plates with industrial rubber.

// Will the flexibility of the steel cable and mooring not lower the efficiency of the system?     No - The structure will appear flexible in very big waves and in strong sideways current when seen from a distance.

// Will pressure loss in the pipes not impact on the system efficiency?  Yes, but very little. The pressure loss is a matter of pipe diameter. With current designs the pressure loss ranges from 0,2% - 7% and peaking when the energy production is at its peak.

 

 

 

 

 

 

 

Lab test

The concept has been tested in the wave tank of the University of Aalborg. Tests in irregular waves at 4 different wave states proved the system efficiency with various numbers of collectors, various distances between collectors, various loads on the collectors and waves from different heading angles.

The bars show efficiency for 1 plate at different wave states (1-4m)

Wave state 1 13%

Wave state 2 7%

Wave state 3 4%

Wave state 4 2%

 

The decreasing efficiency at higher wave states is a huge advantage, as this will allow for a more cost efficient design, since forces are reduced in strong waves where the available energy exceeds the handling capacity of any reasonably dimensioned power take-off system.

Chart

Oblique wave lowers the efficiency. The circles shows efficiency of waves at 30 degrees compared to 0 degrees.

Wave state 2 - 30°

76%

Wave state 3 - 30°

82%


The impact of oblique waves is less than we had expected and decreases when waves are bigger.

The full test report can be found under documents.

0 HOURS OF SYSTEM DATA
0 HOURS TO DEPLOY
0 HOURS TO RETRIEVE
0 HOURS ON MAINTENACE

Proof of concept

A 1:9 scale model was operated successfully for 7 months at Nissum Bredning in 2013. The figure below shows the 50 m string with 8 ECs before deployment from the beach at Nissum Bredning.

The 8 mounted EC’s maintained their efficiency during the test period without maintenance, despite heavy biofouling and millions of wave cycles. Much was learned about the hydraulic cylinders, valves, and the use of seawater as a hydraulic fluid.

 

Furthermore lessons were learned on the handling of a full string in deployment and mooring.

Although Nissum Bredning is excellent for testing systems, deployment and influence of biofouling, the waves at Nissum Bredning are very calm. Hence, neither realistic energy production, nor testing the mechanical limits of a concept is feasible at this test site. On days with heavy wind the energy output was however close to the calculated forecasts.

On the chart below these days are marked along with the predicted curves.

Chart

 

 

 

 

 

 

 

Prototype at 1:2 scale

The DanWEC test area is located 2Nm SouthWest of the Port of Hanstholm.

Significant wave height up to 8.2 meters and single waves up to 15 meters.

Cross current up to 3.1 knots.

The prototype project ran from 2015 to 2019 and included several development iterations increasing the energy production and durability in each iteration.

In the first iteration two energy collectors were each fitted with a 4 m2 plate. In the second and third iteration a total of 4 energy collectors were each fitted with a 7 m2 plate. In our last iteration the energy collectors were each fitted with a 8.5 m2 plate.

The last version was a 100-m string with the possibility of attaching 6 energy collectors. In the last iteration we tested 4 energy collectors simultaneously.

Different storm protection systems were tested in parallel on the energy collectors. The storm protection system reduces the plate area when forces get too strong.

Data from the loads and the energy production was collected on a computer on the inner buoy and uploaded to a server. The data was analysed and compared to the predictions from the Wavepiston Load and Energy Tool developed in collaboration with the Technical University of Denmark. The identified improvements in the design will be implemented in the next projects at full scale in Gran Canaria and Isola Piana.

 

 

 

 

 

 

 

Demonstration at 1:1 scale

Competitive wave energy to islands

The PLOCAN test area is located 6 Nm South of the Port of Las Palmas.

Significant wave height (Hs) up to 5.8 m and single waves (Hmax) up to 9.30 m.

Cross current up to 1.4 knots.

The full-scale demonstration system consists of a single Wavepiston WEC (the string) with 24 energy collectors (length 200 m, width 8 m) and a turbine generator on the PLOCAN platform for conversion to electricity.

The project period is December 2018 – December 2020. The purpose is to demonstrate a full-scale Wavepiston system with electricity conversion connected to a grid and prepare for the first commercial projects.

The system is expected to have a peak effect of 200 kW, being able to produce 547,000 kWh per year (equal to the electricity consumption of 140 standard households).

EU

This Project has received funding From the European Union ́s Horizon 2020 Research & Innovation SME Instrument Programme Grant Agreement 830036

 

 

 

 

 

 

 

Wave to energy and water

Isola Piana is a small tourist Island located 3 Nm West of Portoscuso.

Simulations on wave and current data show a significant wave height (Hs) up to app. 4.5 m and single waves.

Cross current up to 2 knots.

The project period is 2019 – 2021.

The project consortium consists of Vryhof Anchors (Mooring), Wavepiston (Wave Energy), Fiellberg (Hydraulics and Desalination) and Ener.Med. (Grid, Monitoring and Control). Together we assemble the multidisciplinary technologies needed to demonstrate the benefits of a combined system of using wave power for electricity conversion and desalination.

In collaboration with the local community of Isola Piana and the local authorities a full-scale Wavepiston wave energy converter will be installed of the coast of Isola Piana. The wave energy converter leads pressurised water to shore for onshore conversion to electricity and desalination to supply clean power and desalinated water to the island.

The system is expected to have a peak effect of 100 kW - 150 kW, being able to produce 280,000 kWh and 28,000 m3 desalinated water per year.

EU

This Project has received funding From the European Union ́s Horizon 2020 Research & Innovation FTI Instrument Programme Grant Agreement 831041

Wavepiston logo
Vryhof Anchors logo
Nurmi logo
Enermed logo

 

 

 

 

 

 

 

 

Our plan

 
Commercial
by
2022
200
  • €/MWh
  •  
1
  • €/m3
  • Desalinated water
Utility Scale
from
2030
30
  • €/MWh (target)
  •  
0.25
  • €/m3 (target)
  • Desalinated water
 

Videos





Photos

Documents

Report
on calculations
by Niras
Report on tests
at AAlborg University
(scale 1:30)
Report on test
at Nissum Bredning
(scale 1:9)
 
Primary patent
Wavepiston brochure
Expert statements
Report on test at Hanstholm, The North Sea (scale 1:4 – 1:2)

 

Our partners

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DTU logo
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Memberships

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Partnerskabet logo
 Energy Innovation Cluster logo

 

Our team

Michael Henriksen profile photo

Michael Henriksen

CEO
M.Sc. Economics and Business Administration.
Jakob Wedel-Heinen profile photo

Jakob Wedel-Heinen

CTO
Ph.D. Maritime Engineering.
Stefan Skov profile photo

Stefan Skov

Project Director
B.sc. Mechanical Engineering.
Asger Kej profile photo

Asger Kej

Chairman of the board
M.Sc. Hydraulics and Environmental Engineering.
Torben Arnth Nielsen profile photo

Torben Arnth Nielsen

Board member
DIEU Executive Management and Bank School
Martin von Bülow profile photo

Martin von Bülow

Chief Specialist
B.sc. Mechanical Engineering.
Peter Grøn profile photo

Peter Grøn

Operational Manager.
M.Sc. Mechanical Engineering.
Troels V. Lukassen profile photo

Troels V. Lukassen

Development Engineer
M.Sc. Mechanical Engineering.
Henrik Blicher Schmidt profile photo

Henrik Blicher Schmidt

Numerical Modelling & Hydrodynamics
Ph.D. Mechanical Engineering
Telem Avidor profile photo

Telem Avidor

Student Assistant
M.Sc. Mechanical Engineering Student.
Oscar Helmersen profile photo

Oscar Helmersen

Development Engineer
M.sc. Mechanical Engineering.
Kristian Glejbøl profile photo

Kristian Glejbøl

Lead Engineer
Ph.D. Mechanical Engineering
Andreas Hansen profile photo

Andreas Hansen

Development Engineer
M.Sc. Mechanical Engineering.
Noelia Pericon profile photo

Noelia Pericón

Gran Canaria Manager
International relationships, International law and foreign affairs & B.Sc. Business Administration.
Lars Bonnichsen profile photo

Lars Bonnichsen

CFO
M.Sc. Economics and Business Administration, Accountant and Bank School.
Kronborg 10,
3000 Helsingør, Denmark

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