Bioinspired turbine blades offer new perspectives for wind energy

Wind energy is becoming a significant alternative solution for future energy production. Modern turbines now benefit from engineering expertise, and a large variety of different models exists, depending on the context and needs. However, classical wind turbines are designed to operate within a narrow zone centred around their optimal working point. This limitation prevents the use of sites with variable wind to harvest energy, involving significant energetic and economic losses. Here, we present a new type of bioinspired wind turbine using elastic blades, which passively deform through the air loading and centrifugal effects. This work is inspired from recent studies on insect flight and plant reconfiguration, which show the ability of elastic wings or leaves to adapt to the wind conditions and thereby to optimize performance. We show that in the context of energy production, the reconfiguration of the elastic blades significantly extends the range of operating regimes using only passive, non-consuming mechanisms. The versatility of the new turbine model leads to a large increase of the converted energy rate, up to 35%. The fluid/elasticity mechanisms involved for the reconfiguration capability of the new blades are analysed in detail, using experimental observations and modelling.

Modular Repowering of Power Plants With Nominal Ratings Lower Than 180 MW: A Rational Design Approach and Its Application to the Italian Utility System

The paper describes the rationale, the technical/economical details and the results of a study which is part of a large-scale energy conservation program enacted by the Italian Public Utility (ENEL), within a broader framework of structural interventions on the national electricity production/transportation/utilization network. The objective of the larger, long-term plan is to increase by a significant percentage (>5 percent) the net conversion efficiency of the national system. The purpose of the present study is to “recover” a large number of nearly obsolete steam power plants by converting them to a combined cycle configuration. The expression “generalized repowering” has been used to synthetically describe this plant reconfiguration plan, and will be employed in this paper. After giving a brief description of the existing Italian electricity generation situation, we list some possible criteria for repowering and describe in detail the configurations which were considered to be feasible. Finally, the proposed options are comparatively analyzed, and the major parameters which can be of importance in the actual decision-making process on the part of the Public Utility are computed and presented in tabular form. In the conclusions we try to put the present work in the broader perspective of a largescale (supernational), economically sound and ecologically acceptable energy conservation program.