Offshore wind energy

Cost reduction is a key factor in the transition towards a larger share of renewable energy. Like many governments, the Dutch government has set ambitious targets: the installation of an additional 4GW in offshore wind Dutch offshore waters by 2023. Deltares is contributing to this goal in several applied research and consultancy projects. In collaboration with the  FLOW–consortium, the Topsector Offshore Wind (TKI-WOZ) and industry partners, several innovations are being developed. To quantify the cost reductions, a cost model is being developed by the consortium to analyse the effect of individual innovations.

Offshore tidal and wave energy

Alongside offshore wind, developments in tidal and wave energy are growing steadily. Deltares can advise about site selection: where can the maximum amount of energy be harvested and where are seabed conditions most favourable. Furthermore, we have extensive expertise relating to hydrodynamic loads on support structures and three-dimensional current patterns in offshore waters.

Alternative wind turbine support structures

The vast majority of support structures for offshore wind turbines consist of monopile foundations: circular piles with diameters of between 4 and 8 metres. In deeper waters, alternative foundation types are required, such as jacket foundations, gravity-based structures, tripods, and suction piles, and floating wind turbine foundations may actually be required in even deeper waters. Deltares has experience with the physical and numerical modelling of many foundation types and we help project developers and engineers to choose from different foundation concepts. An specimen project involving extensive studies of GBS foundations can be found in the project list.

Pile installation techniques

The traditional installation technique for foundation piles is to drive piles with a large hydraulic hammer. The downside of this method is the resulting underwater noise and the potential ecological impact. To reduce underwater sound levels, vibrating could be a viable alternative. It is, however, still not clear whether lateral stability is comparable with impact-driven and vibro-installed piles. Deltares is developing numerical codes (the material point method) to simulate pile installation and lateral loading by wind turbines that will be validated using laboratory and field measurements.

Scour development around support structures

Scour development (local erosion) around monopile foundations has a negative effect on fatigue life. There are two ways of addressing this problem: increasing the material consumption in the foundation or applying a scour protection to prevent the erosion of the seabed. Deltares helps developers and engineers to make the most cost-efficient decision for every offshore wind park.

Metocean conditions and Operational forecasting

In offshore renewables, Operational Expenditures (OPEX) account for a significant proportion of the total costs. To help offshore planners, Deltares develops decision support systems with our FLOW partners. These systems deliver real-time predictions of the relevant metocean parameters such as wave heights, wind speeds and current velocities inside the wind park and along the shipping routes. An example is the “Meteo Dashboard”.

Multi-purpose use of offshore platforms

The network in the North Sea is becoming increasingly dense: oil & gas platforms, renewable energy foundations, shipping lanes, fishing grounds, military exercise grounds, sand extraction areas and so on. The need to combine multiple functions in the same infrastructure will therefore increase. As part of the European 7th Framework Programme, Deltares is investigating this topic in the MERMAID-project.