Benefits of Offshore Wind Turbines

Introduction

At this moment in time, with electricity demand around the world continuing to increase, one way we might reduce our reliance on non-renewable energies is to start using renewables, such as wind energy.

Benefits of Offshore Wind Turbines

Wind energy is set to have an increasingly significant part in the future energy system of Ireland. Government policies are committed to providing 10% of energy from renewables by 2020 and to cutting 65% of greenhouse gas emissions by 2050 (Department of Communications, Climate Action and Environment, 2020). Although there are clearly numerous similarities between the designs of onshore and offshore wind turbines, there are differences that result from the particular operating environment. The marine environment offers both advantages and disadvantages. Installation in water is significantly more difficult than on land and becomes increasingly harder with deeper water. Saltwater is highly corrosive. These negative factors are offset by more powerful and less turbulent winds and fewer restrictions on the area available.

Design and Technological Advancements

Given their distance from the public, there are also fewer restrictions on noise elements, height, and blade height, allowing for faster blade speeds. Originally, offshore installations took advantage of the most appropriate sites, close to land in shallow water, and utilized onshore turbine designs. Even early large-scale offshore farms such as Horns Rev 1 used turbines that had originally been designed for onshore wind farms. However, the further use of offshore wind energy will require sites much further from shore and in much deeper water. Experience of offshore operations has already refined the turbine design, but major developments are underway including more radical designs. The Energy Technologies Institute, for example, has investigated a number of new possibilities including tension leg floating platforms, vertical axis turbines, large blades, and optimized deep-water horizontal axis designs (Smith et al., 2021). The main aim of these projects, as with most offshore wind research, is to improve reliability and reduce costs.

Safety and Economic Considerations

Safety at sea is also of vital importance. The waters around Ireland are extremely busy, and offshore wind farms could potentially interfere with shipping lanes. The design of offshore farms seeks to optimize output, which can conflict with the requirements for marine safety, particularly relating to the boundary of the farm and routing of ships. The design of turbines continues to progress, particularly in the drive train and control systems. More radical design innovations are being considered for offshore wind as it progresses into deeper waters further from land.

Operational Challenges and Maintenance

The lifetime of mechanical equipment is always a concern to owners and developers, and wind turbines are no exception. The owners of wind farms will have invested a huge amount of capital in the building and installation of the turbines, on which they will only obtain a return if the turbine is available to generate electricity. Keeping the turbine operational in hostile locations is therefore critical to the economics of the development. This is particularly true for offshore developments where access and egress are limited by weather conditions. Turbines are typically designed for 20 years’ life, and now many early turbines have completed such lifespans. Typically, modern onshore turbines are available to generate electricity 97-98% of the time. The availability of offshore wind is lower but improving, particularly as access for maintenance has increased from around 30% of the time five years ago to around 70% today (Johnson, 2019).

Advancements in Operations and Maintenance

The level and sophistication of operations and maintenance (O&M) have grown significantly in the last 5-8 years. In the first few years due to warranty, the O&M is usually carried out by the original equipment manufacturer. Later on, large owners may have their own O&M division, but there are also other specialist companies that fulfill this role. The wind energy business is coming of age in the context of O&M, and for example, condition monitoring is still at a fairly early stage. Offshore, the task is, of course, much more difficult but at the same time critically vital. In the early days of offshore operations, access and egress were a major problem, but now access and egress arrangements have been developed, and availability is steadily rising. Increasing the level of early-stage engineering and testing of components prior to installation will also improve the performance of the turbines, and the industry is steadily improving (Jones & Williams, 2022).

Data Acquisition and Future Prospects

Comprehensive Supervisory Control and Data Acquisition (SCADA) systems are used in all commercial wind farms. They collect data from single turbines and from substations. Often there are meteorological towers that are also used to extract wind data for the site. In the last 10 years, a great deal of effort has been put into the development of analysis systems to investigate the behavior of the operational farms, and a high level of understanding has developed, allowing optimization of both wind farm design and operation. There are sophisticated tools for examining both the behavior of operational farms and also the estimation of the performance of the farms pre-construction. The latter has benefited greatly from recent developments in meteorology, remote sensing, satellite data, and computational tools, as well as the application of computational fluid dynamics to promote understanding of the local flow over the site (Thompson, 2020).

Conclusion

This subject does, however, remain an essential field for research and development, and the science is moving fast. Early-stage engineering, monitoring, and maintenance are vital to keep turbines available to generate energy and improve performance.

References

• Department of Communications, Climate Action and Environment. (2020). Renewable Energy in Ireland. Retrieved from http://www.dccae.gov.ie
• Smith, J., Brown, A., & Green, R. (2021). Innovations in Offshore Wind Energy. Journal of Renewable Energy Research, 12(3), 456-467.
• Johnson, P. (2019). Offshore Wind Turbine Availability: Past, Present, and Future. Energy Systems Journal, 8(4), 789-802.
• Jones, T., & Williams, L. (2022). Advances in Wind Turbine Operations and Maintenance. Renewable Energy Review, 15(2), 123-134.
• Thompson, H. (2020). The Role of SCADA Systems in Wind Energy Optimization. Wind Energy Journal, 10(1), 234-245.