Norway has committed to cutting greenhouse gas emissions by 50-55 percent by 2030 and by at least 80 percent by 2050. If these goals are to be reached, we require a transition in energy carriers, from petroleum to renewable resources. Onshore and fixed offshore wind have transitioned to become a mainstream source of electricity over the past decades. However, there is increasing resistance in local communities against onshore wind farms because of environmental impact and loss of natural habitats. It is therefore imperative to find alternatives to onshore wind farms that are more environmentally friendly and have a smaller visual footprint. An obvious alternative is to move wind farms further off shore. At first sight this seems like an impelling alternative and fits nicely with the green transition Norway has just started, building on expertise developed in the maritime, fish farming and offshore oil & gas industries. However, installing and operating wind farms in deep waters far away from onshore operations and maintenance sites is definitely not straightforward.
The first commercial floating wind farm was deployed in Scottish waters, and new developments are underway both in Norway and internationally. But floating wind poses additional challenges to onshore and bottom-fixed offshore wind, and requires special attention during planning of farms and design of turbines and structures. Although the offshore wind industry is advancing rapidly, these challenges must be addressed for floating wind to become a reliable and cost-effective energy carrier.
Norway is taking the lead
Sponsored by the Norwegian Research Council, a Norwegian consortium has been established to develop a new software platform for design and simulation of floating offshore wind farms. The consortium is headed by DNV and has participation from the leading national R&D organizations and industry partners. The consortium has established a project with the overall objective to significantly improve the accuracy, security and efficiency of design processes for offshore wind farms and floating turbines.
By extending industry knowledge and developing innovative methodologies and simulation tools for floating offshore wind farms, investors/planners, designers/engineers and owners/operators will obtain a more accurate decision basis when making new investments into floating offshore wind projects. An R&D project, named ImproveFLOW, was kicked off on June 21st and the outcome will be a state-of-the-art multi-disciplinary simulation platform that will also incorporate modern, advanced 3D visualization capabilities and collaborative workflows. The underlying idea for this project is to extend and further develop state-of-the-art cloud-based simulation and visualization technologies, customize and apply these technologies towards floating wind resource assessment and aero-hydro-elastic analysis.
The need for R&D
In order to design and build cost effective wind farms based on floating installations several important challenges need to be overcome.
Figure 1 Wake pattern and interaction affects in floating offshore farms will be studied in detail.
A key challenge for floating offshore energy production is that turbines and floaters are subjected to interaction effects which vary with both wind and wave conditions. To offer a higher level of certainty for investors in floating wind, it is important to have accurate prediction methods to estimate the annual energy production. Current prediction methods are based on onshore and fixed offshore wind farms. Hence, it is necessary to develop more accurate estimates of interaction between turbines, floating structures and mooring lines, so that the total performance can be accurately predicted. Combination effects of floater motion, wake patterns and wind farm control on energy production will be studied in detail.
Another challenge is the need to run a coupled analysis of the floater and the turbine in a secure manner. Different coupling strategies can significantly influence on the performance and accuracy of the simulations results. Floaters and turbines are typically designed by different companies, using different software tools. Because of protection of intellectual property (IP), the willingness to exchange model and results data is often limited, resulting in use of assumptions and simplified models. These leads to inaccurate analysis results and an inefficient design process. Hence, it is necessary to develop a framework for collaborative analysis workflows and secure data exchange
which satisfies IP concerns of the turbine- and floater manufacturers.
Figure 2 A flexible software platform will allow for investigation and comparison of different floating turbine concepts
A third challenge is the large number of load cases needed in order to cover all wave, wind and turbine state combinations needed to evaluate quality and ensure compliance of design alternatives. This results in many simulations to be run. Therefore, it is necessary to develop methodologies and solutions that allow more efficient analysis utilizing cloud-based high-performance compute resources, so that compliant design-space alternatives are completely explored and correctly evaluated.
The knowledge resulting from the project will ensure that Norway maintains a leading position in the floating offshore wind industry – and contribute to overall competitiveness and adaptability of the entire maritime and offshore industry and public sector. But more importantly, contributing to develop the floating offshore wind industry will hopefully result in sustainable exploitation of renewable energy resources, reduced greenhouse gas emissions and more reliable energy supply.