Seafloor screw piles
The total capacity of the offshore wind sector in Europe grew by 18% in 2018 alone. The prospect of larger turbines and deeper waters present a challenge to the current methods of driving foundation “pin” monopiles into the seabed floor.[2,3] Screw piles (helical piles) have been proposed as a potential innovative alternative for offshore wind installations in depths of 30-60m.
Even in shallow waters, fabrication and installation of offshore foundations make up 20% of the overall project costs, and these costs rise exponentially with increasing water depth. Screw piles for jacket-based foundations - those that are used in deeper waters - are forecasted to reduce installation time and cut costs by 33%. Screw piles can easily be removed and reused, which will facilitate the eventual decommissioning or repurposing of the structures.[7,8]
Screw piles are already sufficient in terms of both tensile and compressive strength to be used as foundations.[2,4] Current methods of hammering monopiles continue to raise concerns about their disturbance to marine mammals, the seabed, and subsea plant life. Screwing produces less noise and vibration during installation. However, screw piles are currently limited in diameter, and mostly suitable for installation sites in soft and medium soil types. As offshore wind is moved into deeper water, screw piles may offer a solution to the challenges of driving piles in deeper waters.
When will it become accepted practice to use screw piles instead of foundation piles for offshore wind installations?
 Komusanac, I., Fraile, D., and G. Brindley (2019), Wind energy in Europe in 2018
 Screw piles for offshore wind (2020)
 Spagnoli, G. (2013), Some considerations regarding the use of helical piles as foundation for offshore structures. In Soil Mechanics and Foundation Engineering
 Al-Baghdadi, T. (2018), Screw piles as offshore foundations: Numerical and physical modelling.
 Kitzing, L., & Morthorst, P. E. (2015), Trends in offshore wind economics – the past and the future. In Proceedings - 14th Wind Integration Workshop
 Davidson, C., Al-Baghdadi, T., Brown, M., Knappett, J., Brennan, A., Augarde, C. E., Blake, A. & Ball J. (2018), Centrifuge modelling of screw piles for offshore wind energy foundations. In 9th International Conference on Physical Modelling in Geotechnics
 MacLean Dixie HFS. (2020), Petroleum / Pipelines.from MacLean Dixie HFS
 Byrne, B. W., and Houlsby G. T. (2015), Helical piles: an innovative foundation design option for offshore wind turbines.
 Saleem, Z. (2011), Alternatives and modifications of Monopile foundation or its installation technique for noise mitigation.
Wind Europe (2018), Offshore wind in Europe grew 25% in 2017
Passon, P., Branner, K., Larsen, S. E., & Hvenekær Rasmussen, J. (2015), Offshore Wind Turbine Foundation Design
Davidson, C., Al-Baghdadi, T., Brown, M., Brennan, A., Knappett, J., Augarde, C., & Ball, J. (2018), A modified CPT based installation torque prediction for large screw piles in sand.