Grantee Research Project Results
Final Report: Harvesting Wind Energy with Existing Bridge Underpass Infrastructure
EPA Grant Number: SU835076Title: Harvesting Wind Energy with Existing Bridge Underpass Infrastructure
Investigators: Benoît, Jean , Gherardi, AJ , Bell, Erin , Travers, John , Steward, Joshua , Schindler, Leanne , Naylor, Michael , White, Samuel , Fu, Tat
Institution: University of New Hampshire
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities
Objective:
The goal of this project is to help provide renewable clean energy to thousands of bridges by using wind power generated in bridge underpasses. In this way, bridges may become independent of the electrical grid, and the carbon footprint of the transportation infrastructure will be reduced. As part of this effort, this project investigated wind patterns from traffic and natural wind flow through bridge underpasses in order to harvest the required energy for powering structural health monitoring systems (SHMs), emergency warnings, signalization and lighting. Using existing structures and wind patterns to generate sustainable energy is both economically attractive and highly innovative. If this objective were to be reached, access to the grid in remote areas and in developing countries would no longer be necessary.
The ultimate goal of the project will be to create a protocol for implementing wind turbines on existing and new underpass bridges. Attributes including bridge location, bridge width, bridge orientation, bridge architecture, site topography and vegetation, energy demands, wind climate, wind characteristics near and under the bridge, traffic, and more will be important factors in determining the efficiency and practicality of implementing a wind turbine on a given bridge. The expected outcome of this project is to develop a selection process that weighs several factors in selecting bridges suitable for wind energy harvesting. The benefit to developing a protocol will be that it could be applied anywhere to identify candidate bridges for wind turbine installations.
The project team objective is to determine which factors are the most significant in the selection process. Those factors would be evaluated early on in the selection process to effectively narrow down the possible bridges. In order to determine which factors are significant, the project team will study the Bagdad Road Overpass Bridge located in Durham, NH. The bridge is a four span bridge owned and operated by the New Hampshire Department of Transportation. The two longest spans are the center spans at 60 feet each. One of these center spans accommodates the traffic flow, while the other center span is currently vacant. The two end spans are 45 feet each. Including the abutments, the bridge is 213’-4” long. The bridge has two traffic lanes with a total width of 44 feet.
The Bagdad Road Bridge will be used as a template to establish a selection procedure. During the course of the project, a physical scale model of the bridge and surrounding terrain will be created and tested in a large wind tunnel facility located on the UNH campus. During the model testing, different attributes for the selection process will be compared. In each test the wind speed in the bridge underpass will be measured with respect to the given free stream (wind tunnel) wind speed. The model will be tested with different angles of wind approach, different wind speeds, different bridge widths, and different topographic layouts. In addition to the model testing, field data from the site will be collected to validate the laboratory measurements. The project team will create wind roses for the location and wind maps will be compared to actual field measurements. Once the field data and model data have been recorded, the data sets can be compared to each other and the most beneficial attributes can be identified and ranked.
Conclusions:
At this point in the project, the team is still in the process of collecting data. We expect the wind velocity in the bridge underpass to increase compared to the free stream velocity for the dominant wind directions at this site. The bridge approach and underpass, if shaped in a way that promotes it, will act like a contraction and accelerate the air flow as it passes under the bridge. One of the expected outcomes is that topography, vegetation and bridge underpass landscape will be the major factors, as they modify the natural wind conditions. Wind contributed from traffic is expected to be a minor factor. The “natural wind condition”, or wind climate, in Durham, NH is generally not favorable for wind energy installations, as wind maps show small wind velocities in the area (with average wind speeds at 80m hub height on the order of 4 m/s). However, due to the bridge and site layout the natural wind will be intensified. As wind power scales with wind velocity to the third power, a significant increase in wind power density under the bridge is expected. Traffic-generated wind is expected to be a minor factor in contributing to wind turbine energy production. This is because turbines only start producing energy when a certain cut-in wind speed is achieved for a significant amount of time, whereas the wind created by passing vehicles is intermittent and of short duration. Further data collection will help verify these expectations assessed thus far by the civil and mechanical engineering students. The data collection and analysis will be completed by the end of the project period.
At the end of testing, the project team expects to have a recommendation for the most suitable location for turbine placement in the underpass. To help in understanding turbine size and types, the project team is collaborating with personnel at the Boston Museum of Science to discuss various options. The wind tunnel lab at the Museum studied several different types of turbines: Windspire, Skystream, AeroVironment, The Swift, and Proven. From our initial visit, the team expects a vertical axis wind turbine such as the Windspire to most likely be a good fit for the bridge being studied. While choosing a turbine, certain considerations such as snow and ice spun off blades, structural impacts, and maintenance must also be taken into account.
Supplemental Keywords:
renewable energy, wind energy, sustainable infrastructure design, sustainability monitoring, alternative energy source, bridge underpassesThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.