Selection of an optimal lattice wind turbine tower for a seismic region based on the Cost of Energy

Abstract

Over the past few decades, wind has emerged as one of the major sources of green and renewable energy for being a cost effective solution and offering a substantial reduction in greenhouse gas emissions. Currently, onshore wind energy is undergoing a rapid development and expansion at an annual rate of approximately 27%. As such, more and more wind farms are being established in earthquake prone areas resulting from the availability of wind energy in these regions. This paper investigates the optimal selection of lattice wind turbine towers in seismic regions based on the Cost of Energy (COE). Although, various different tower types and materials (e.g., steel and concrete-steel composite monopole) are available, this study focuses on steel lattice towers for providing a cost effective solution and for posing a challenging structural optimization problem. To the knowledge of the authors, design optimization of lattice wind turbine towers subjected to combined earthquake, wind and gravity loading has not been performed before. Ten tower height-wind turbine size combinations are generated by placing turbines with 100 to 400 kW power generation capacity on towers having 24 to 42.6 m height, and a cost optimal solution is obtained for each combination. Taboo search algorithm is used to minimize the total cost. The wind and earthquake loads on the towers are obtained for a specific case study location. The COE for each combination is calculated using three different wind probability distributions. Instead of using simplified structural models, all the details of a rigorous structural analysis, e.g., geometric nonlinearity, are included in the finite element models. Realistic loading conditions, including wind and earthquake, are considered.