Comparative life cycle assessment of tubular wind towers and foundations – Part 2: Life cycle analysis

In the first part of the paper the design of tubular towers and respective onshore foundations was addressed. The considered solutions were based on steel, concrete and hybrid steel-concrete tubular towers supporting multi-megawatt turbines of 2, 3.6 and 5 MW power with hub heights of 80, 100 and 150 m respectively. In this second part of the paper, the life cycle analysis of the designed case studies is performed and conclusions about their environmental impact are drawn. Two different scenarios concerning the lifetime of the towers were established. The first scenario considers 20 years lifetime and two different construction methods for the connection of the steel segments, the first based in current technology using flange connections and the second using newly developed friction connections. Assuming equal importance for all environmental categories in this scenario, it may be concluded that for heights up to 100 m hybrid towers with friction connections are the most efficient solution. For higher heights, the concrete tower becomes more efficient. The second scenario considers an increased total lifetime of 40 years, assuming the reuse of the tower after 20 years of operation. In this case, the use of friction connections in steel towers enhances the possibility of dismantling and reusing the tower potentiating much better performance in relation to the environmental category of global warming.