Offshore Wind Energy in India: Foundation Design and Challenges

Abstract

Offshore wind industry has made rapid advances in Europe particularly in the UK. Foundations for the Offshore Wind Turbines (OWT) form nearly 30% of the total cost and currently monopiles are the most popular form of these foundations. As the offshore wind industry moved to south-east asia including Japan, South Korea, Taiwan and China, the performance of OWT foundations under seismic loading has become important and there is much of current research in Cambridge directed towards this loading scenario. Offshore Wind is becoming popular in India with two sectors for wind farms already identified, one on the East Coast near Kanyakumari and the other offshore of Gujarat. In this paper, the design challenges for these two sectors will be considered. In the first part of the paper, the OWT foundations in the form of monopiles located in soft marine clays underlain by stiffer clay strata often present along the East Coast will be considered. The recent research using centrifuge modelling that is aimed at understanding the behaviour of monopiles under monotonic and cyclic loading will be highlighted. The results shows that realistic p-y curves can be generated directly from the centrifuge test data that capture the lateral monopile response in clays. In the second part of the paper the challenges of offshore wind development on the West Coast i.e. offshore of Gujarat will be emphasised. The recent research on earthquake loading and the seismic performance of monopile foundations in loose sandy soils overlying dense sandy strata will be considered. Recent design guidelines developed by Det Norske Veritas (DNV) that require the consideration of seismic load and operational wind/wave loading in tandem, and the recent research at Cambridge to test these load combinations will be highlighted. It will be shown based on centrifuge test data that the monopile response in liquefiable soils is significantly altered in the presence of operational wind/wave loading.