Sea of Energy

In 2010 the European Commission introduced Energy 2020 – a strategy for competitive, sustainable and secure energy, which contains among others the intention to reduce the European greenhouse gas emissions by at least 20 per cent by 2020 and increase the use of renewable energy to 14 per cent. This has led to increased development of renewable energy sources.

Wave and tidal energy is one of those renewable energy sources being examined, developed and tested and has been designated as an avenue of great potential in this same strategy. Maritime Holland dived into the sea of technologies available and current projects.

Although not everybody is optimistic, Siemens for example pulled out of tidal energy by divesting the part of their company involved, about 70 per cent of wave and tidal energy technology developers and deployment sites are located in Europe, according to the same European Commission.

They also see some serious challenges and bottlenecks on the road to using wave and tidal energy for commercial use, such as a high levelized cost of energy (LCOE, meaning the price at which electricity must be generated from a specific source to break even over the lifetime of the project), finding financial closure for projects and potential difficulties in the development of grid access and infrastructure. However, the developments are moving forward, with an increasing reliability and operability of devices. The European Union expect to reach around 35 MW of installed tidal energy capacity in 2017 and 25 MW of wave capacity in 2018.

Wave energy

Waves are created under the influence of the wind. Small ripples can become big waves, depending on the strength of the wind. With them the waves carry energy, of which the density depends on the volume of the liquid, acceleration of the gravity and the wave height. In order to extract this power from the ocean bottom mounted as well as floating devices can be used. In 2000 the world’s first commercial scale wave energy device was built into the coastline of the Island of Islay in Scotland. WaveGen, which is now part of Voith Hydro, installed a shore-based, grid connected wave power unit with a capacity of 500 kW, which uses an oscillating water column to drive air in and out of a pressure chamber through a Wells turbine.

Tidal energy

Tidal energy is established by extracting the energy created by the flow of the currents. The gravitational forces of the sun and the moon cause the tides, ebb and high tide, which in turn causes a shift in the water level. The kinetic energy in the moving mass of water can be converted to electricity by a tidal current turbine. In 2003 the world’s first offshore tidal turbine was installed near Lynmouth in Devon, the United Kingdom, by Marine Current Turbines (MCT), the Seaflow 300 kW. In 2008 the same company completed the installation of the world’s first commercial scale tidal turbine; the SeaGen S with a capacity of 1.2 MW, in the Strangford Narrows in Northern Ireland.

Potential in the Netherlands

So worldwide developments in wave and tidal energy are in full swing. What about Dutch companies and their involvement in this type of renewable energy?

A recent study, performed by Ecofys, Blueconomy and the Netherlands Water Partnership (NWP) for the Dutch Ministry of Economic Affairs, showed opportunities and hurdles for the Netherlands in developing wave and tidal energy. The goal of the study was to gain insight into the export potential and the possible role the energy source could play in the Dutch energy system.
According to this research the Netherlands is amongst others a front-runner in demonstration of tides and tidal current energy conversion and in the R&D concerning wave energy, says Frank Wiersma of Ecofys. He presents three conclusions the study has made apparent:

1. The opportunities for technologies for energy from water are sizeable, but the size of the potential market will depend on cost reduction relative to cost of competing options and the pace at which the technologies can be demonstrated, de-risked and scaled up;
2. The Netherlands is well positioned to play an important role internationally in a number of these technologies. There is cross-over potential with water technology, delta technology and offshore sectors.
3. Pro-active steps can contribute to lowering hurdles for onward development. Arrive at a joint vision from Government and the sector for home market deployment as a basis for onward development of technologies and projects and exports. Enable onward investment in technology development to enable cost reduction.

The Afsluitdijk

Indeed, in the Netherlands several projects are carried out, though in comparison to tidal energy there are not as many wave energy projects executed in the Netherlands. Dutch companies however, are actively involved in the development of wave energy technologies and installations abroad, especially in Great Britain and Portugal where the waves are more suited to generate power. In the area of tidal energy a lot of projects are taking place in the Netherlands.

Take for example the demo of a 100 kW tidal turbine from Tocardo Tidal Turbines, that was installed and connected to the Dutch grid in 2008 in one of the the discharge sluices of the Afsluitdijk near the Dutch village Den Oever. The Afsluitdijk is one of the locations in the Netherlands extremely suited for tidal energy, since at low tide in the Dutch Wadden Sea surplus water in the adjacent IJsselmeer is discharged via the sluices twice a day. Tidal turbines installed in the sluices generate energy from this discharge flow. The project has proven to be a great success, as the turbine has been working for six years now, where a lot of other international projects failed because of technical setbacks.

In February 2013 the Energising Deltas project took off. This project aims to combine the generation of sustainable energy with water safety and water management creating an innovative export product. In this programme Tocardo, REDstack and Strukton collaborate with the research institutes Deltares, ECN and EUR, as it is also important to gain knowledge about environmental impact. In the project four water defences are researched: the Afsluitdijk, the Brouwersdam, the Grevelingendam and the Oosterscheldekering. The projects carried out on the Afsluitdijk is a scaling up of the Tocardo project. The intention is to install 30 turbines generating up to 5 MW of energy by 2017 in the ten discharges sluices of Kornwerderzand. In preparation to this demonstration project in 2015 a pilot comprising a set of three turbines will be tested and optimised at the test site in Den Oever. Next to this, a lot of other projects are carried out around the dike. Take for example the Blue Energy pilot, in which electricity is generated by mixing salt and sweet water, in this case when the water of the Wadden Sea and the IJsselmeer meet.

Offshore tidal energy

Last October, it was announced that in the Marsdiep near the Dutch island of Texel a tidal test location will be created. Bluewater, together with among others companies like Damen, TKF, Vryhof and Van Oord, is going to install and test a floating tidal energy platform as a trial for more remote locations worldwide. Allard van Hoeken, head of New Energy at Bluewater Energy Services, called it “a unique joining of forces from leaders in the offshore industry, a group of mostly Dutch companies” during his presentation of the project at Offshore Energy Exhibition & Conference.

The design and fabrication started in 2014, in the beginning of 2015 the platform will be installed and in the second quarter of this year it will be launched. The 200 kW turbine will deliver its tidal energy to Texel. “This platform can be shipped and installed anywhere in the world, to provide clean electricity in remote areas and small islands, replacing expensive and polluting diesel generators”, says Van Hoeken. Therefore, remote locations and small islands can be provided with a grid connection for for example lightning and refrigeration.
One of the goals is to show the advantages of a floating platform which has all electrical equipment dry and accessible at the surface, in contrast to a turbine on the bottom of a sea. Because of its floating and lightweight abilities the BlueTEC-platform is very suitable for remote areas worldwide, since no heavy lifting equipment is required and maintenance is more easy since the platform can be accessed directly for regular maintenance, while for heavy maintenance it can be disconnected and towed to a local harbour for repair.

Anne Kregting