Wind energy harvesting from transport systems: A resource estimation assessment T. Morbiato a,⇑ , C. Borri b , R. Vitaliani a a TrEo Group ICEA Dept., University of Padova, via Marzolo, Padova, Italy b CRIACIV, University of Firenze, via di S. Marta, 3, Florence, Italy highlights  Harvesting wind energy from aerodynamic losses of heavy vehicles is investigated.  The energetic rationale complies with emerging sustainable energy policies worldwide.  Measured correlation of wind speeds with traffic flow allow fitting to any motorway.  Traffic related wind drops could affect transient behavior of the energy conversion device.  The harvestable energy is calculated from traffic-induced wind resource estimation. article info Article history: Received 13 November 2013 Received in revised form 31 May 2014 Accepted 17 July 2014 Available online 12 August 2014 Keywords: Traffic aerodynamic losses Wind energy Truck flow VAWT Sustainable energy policies abstract Many recent patents worldwide address the concept of harvesting wind energy from aerodynamic losses in motorways, however the mechanics of a specific device dedicated to the task has never been described. The lack of a characterization of the energy resource likely explains why the international market is still to acknowledge any technology related to the concept. Here, an experimental activity is presented to investigate the flow field generated by traffic in motorways and eventually develop an innovative tech- nology that complies with emerging energy policies. In the case of traffic source, the energetic rationale seems to have a double motivation: there will always be an optimal energy supply associated with an increment in transport demand and, contrary to other renewables, the transport aerodynamic losses belong to a source of costs, making them a remarkably sustainable energy source. After a thorough anal- ysis of the correlation between truck flow and wind speed classes, the characterization of a resource indi- cator for time of wind above a cut-in speed is given, with an account for the effects of traffic clusters and traffic related wind-drops. We demonstrate how during weekdays daytime hours the traffic-generated resource can allow an energy conversion beyond a threshold possibly permitting a positive energetic bal- ance of the system. A study on the effect of traffic related wind-drops is also carried out to investigate how the issue could be relevant in the transient behavior and ultimately in the performance of a mini wind turbine in the kW-range. While many findings relate to the motorway site where the campaign was sited, fitting of the experimental data to the generic motorway case permits to explore a complete range of traffic flows. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction and motivation By the end of the last decade a considerable number of patents (i.e. [1–3]) appeared on the worldwide scene, addressing the idea of harvesting wind energy generated by traffic. To the best authors’ knowledge, none of the inventions describe the mechanics of a brand new device dedicated to the task. Furthermore, a scientific study to assess the selected resource has never been performed, although it is known that traffic-induced wind properties are quite different from atmospheric wind, to which existing turbines are dedicated. The lack of characterization of such energy resource could explain why the market is yet to acknowledge any technol- ogy related to the cited patents. We report the results of an exper- imental activity started in 2010, whose final objective is to investigate the flow field generated by traffic in motorways and http://dx.doi.org/10.1016/j.apenergy.2014.07.055 0306-2619/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: tmorbiato@treoproject.com (T. Morbiato), dir-dicea@dicea. unifi.it (C. Borri), rvit@dic.unipd.it (R. Vitaliani). Applied Energy 133 (2014) 152–168 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy