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Synthesis of Using Emerging Energy Harvesting Technologies in Transportation Infrastructure

Description:

Transportation infrastructure is traditionally considered a means of fulfilling the mobility needs through connecting communities via commerce and moving people. Financial resources to build and maintain these infrastructures come, for the most part, from fuel taxes (20 cents/gal). However, with increasing numbers of lane-miles added to support the expansion of the population away from cities, and as vehicles become more fuel efficient, funding for maintenance is becoming scarce and our infrastructure will, inevitably, continue to deteriorate. Millions of lane miles subject to solar heat and vibrations, combined with repeated strains under normal working conditions, make these infrastructures great sources for energy harvesting. The current wasted energy can be transformed using efficient systems into usable electric power. Using these infrastructures as a means of harvesting energy is a relatively novel idea that has not been fully implemented yet. Massive amounts of mechanical strain energy is wasted when millions of vehicles are moving on roadways, railways, and bridges. The emerging harvesting technologies can harvest the wasted energy, feed the harvesting energy to the power grid, or save the generated electricity in batteries to charge electric vehicles and power roadside lights, traffic signs, and monitoring sensors. The following list highlights the economic benefits and environmental impact of energy harvesting technologies.

Energy harvesting technologies are:

completely green, having no environmental impact, as opposed to energy generated from burning fossil fuels,

take up no public space as the energy harvesting technologies use existing right of way,

can be implemented in rural infrastructure providing sources of power to remote areas,

use available energy resources from traffic loads, heat, and vibration (not requiring wind, sun, or geothermal sites), and

enable a “smart” infrastructure by gathering real time information on vehicle weight, speed, and traffic volume.

Energy harvesting technologies are not new, but the feasible applications of the technologies in transportation infrastructures are yet to be quantified. Preliminary literature review suggests that the energy harvesting technologies are taking steps for full deployment in Europe roadways however, limited studies have considered the application of the energy harvesting technologies in the United States roadways to date. Currently, California is investing in developing Piezoelectric-based technology for potential implementation and Virginia conducted limited field-testing on their smart road. The Piezoelectric-based technology is a great opportunity for state DOTs to consider for an energy harvesting technology as a source of revenue to raise the economic impact and lower the environmental impact of each DOT’s transportation infrastructure.

Revenues for integrating the generated power from energy harvesting technologies can be used for infrastructure maintenance funds and to offset the reduced revenues from gas taxes. Continuous monitoring of infrastruture will save Department of Transportation (DOT) the associated cost of diagnostics. Collected traffic data can be fed into a traffic management system. Incoporating the generated power for improving street illumination will improve safety in remote areas.

Objective:

There are numerous technologies that surfaced over the last few years in an attempt to use transportation infrastructure in harvesting energy. Some technologies are having unique characteristics and advantages over others depending on their applications. For instance, PZT a candidate technology for railways and steel bridges to convert vibration into useable energy but not in asphalt roadways. Therefore, the objective of the study is to “develop a synthesis document on the current energy harvesting technologies and their feasible applications in transportation infrastructure”. The proposed tasks of the study are:

  • Summarize state of knowledge on existing energy harvesting technologies with promising applications on transportation infrastructure.
  • Develop a guideline document comparing the energy harvesting technologies on the basis of their operation mechanism, energy output, functionality, durability, environmental impact and cost.
  • Provide recommendations on their feasibility, obstacle for implementation and potential use in transportation infrastructure.
Benefits:

A guidance document will be created and become a reference for DOTs on how to identify the optimum harvesting technology for particular application in infrastructure to maximize environmental and economic benefits. The guidance document will also include a process to evaluate the potential environmental impacts and economic gain when key parameters (e.g., traffic load and volume) are identified.

This study will answer the following questions:

  • What are the potential energy harvesting technologies for transportation infrastructure?

  • What are the economic benefits and the environmental impacts of integrating these technology?

  • What are the best-practices or lessons learned from the case studies on implementing these technology on infrastructure?

  • What are the needs for expanding the use of these technologies to maximize their benefits?

Related Research:

Energy harvesting (scavenging) is a process that captures unused ambient energy that would otherwise be lost in the form of heat, vibration, stress, or deformation. Roadways, bridges, and railways are exposed to energy from wheels’ movement, loading, and solar heat. These resources can be potentially converted and stored into usable electric power. Energy harvesting can lead to sustainable transportation infrastructure. Examples of current technologies to harvest energy are:

Energy harvesting using solar collector: The heat in an asphalt pavement surface is accumulated during the day due to the absorption of solar radiation. The concept of an asphalt solar collector involves a piping system that collects pavement heat through an appropriate fluid (Mallick et al. 2009). The piping system can reduce temperature of pavement and surrounding ambient air ultimately reducing the urban heat island effect (De Bondt 2003). However, the structural integrity of the piping system under intense heat and repeated impacts of traffic loads is a still a major concern for roadway engineers. The solar collector technology is highly dependent upon climate conditions and may not be universally viable.

Energy harvesting using TEG: The temperature of an asphalt roadway structure is typically higher at surface and lower at deeper layers, creating a thermal gradient across the pavement (Datta et al. 2016). The thermal gradient can activate thermoelectric generator (TEG) materials to generate electric power. Inserting TEG materials in roadway structures can convert the thermal gradient heat into electric voltage using the Seebeck effect (Liang and Li 2015).

Energy harvesting using piezoelectric transducers: Under traffic loading, pavements are exposed to vibrations, strains, and compression forces that form mechanical strain energy. The mechanical strain energy can be captured and converted to usable electric power using piezoelectric transducers (PZT) (Hill et al. 2014; Ali et al. 2011). PZT have the property of generating an electric voltage when subjected to deformation by dimensional alteration or vibration. Xiong (2014) designed and installed nine different PZT energy harvesters for roadway applications. The conclusion was that the output power from PZT was very low but enough for powering structural health sensors network.

Energy harvesting using photovoltaic: The principals of solar roadways is to use embedded (surface) photovoltaic technology for harvesting solar energy. The photovoltaic technologies are incorporated into the surface replacing the traditional asphalt pavement materials currently used. In 2006, Solar Roadways Inc. built a parking lot covered by solar panels (Mehta et al. 2015). The solar panels in roadway are integrated with heating elements to maintain above freezing temperature. In the Netherlands, the SolaRoad built a 230-feet bike lane with solar panels made of thick glass layers to withstand heavy loads. SolaRoad expects that the power generated from the panels to exceed 3 megawatt-hours after six months from opening (SolaRoad 2016). In December 2016, France constructed the first kilometer-long solar road coated with a clear silicon resin that enables them to withstand the impact of passing traffic. Major concerns are the roads durability to resist traffic impact and preserving surface texture for the safety of motorists. Also, the effect of shading caused by obstructions from buildings, trees, cloudy conditions and from passing vehicles may impact the efficiency of solar roadways.

The reviewed information detailed various technologies, but the technologies did not provide guidance on the best practices of using them in infrastructure for maximizing economic and environmental benefits.

Tasks:

Task 1: Canvas transportation agencies for energy harvesting success stories

  • Obtain sample specifications

Task 2: Canvas regulatory agencies and assemble a state-of-the-practice vision on energy harvesting technologies and the concerns the agencies think need to be addresses to make such implementation of technologies possible

Task 3: Canvas DOTs to obtain existing analytical data on different energy harvesting technologies

  • Ex. Solar collectors, TEGs, Photovoltaic technologies, etc.

Task 4: Synthesize characteristics of energy harvesting technologies

Task 5: Identify areas of optimal use for the technologies

Task 6: Create life-cycle costs and risk analysis for energy harvesting success stories

Task 7: Evaluate benefits and risks of implementing energy harvesting technologies within ROW

Task 8: Identify and evaluate existing policies concerning energy harvesting technologies on roadways and ROW to help agencies make appropriate changes to practices, equipment, facilities, or agency policies when using energy harvesting technologies.

  • Identify gaps in existing practices and policies

  • Convert key information into more “readable” format

  • Compile best existing practices, training materials, or products into single repository

Implementation:

State DOTs are aware of the rising costs pf maintenance and lower amounts of revenue being provided. The DOTs are learning about possible ways to generate more revenue and have a more comprehensive way of collecting statistics and data about use and deterioration. The DOTs would champion this research since the study would provide new information about the implementation of energy harvesting technologies.

Relevance:

Any DOT application that requires small amounts of energy in remote locations.

Sponsoring Committee:AMS20, Resource Conservation and Recovery
Research Period:6 - 12 months
Research Priority:High
RNS Developer:Andrew Graettinger and Samer Dessouky
Source Info:Mallick, R.B., Chen, B. L. and Bhowmick, C., 2009. “Harvesting energy from asphalt pavements and reducing the heat island effect”, International Journal of Sustainable Engineering, 2:3, 214-228
De Bondt, A. (2003). Generation of Energy via Asphalt Pavement Surfaces. Asphaltica Padova.
Liang, G., and Li, P., 2015, Research on thermoelectric transducers for harvesting energy
Datta U., Dessouky S. and A.T. Papagiannakis. (2016) “Harvesting of Thermoelectric Energy from Asphalt Pavements” Transportation Research Record: Journal of the Transportation Research Board. DOI 10.3141/2628-02
Hill, D., Agarwal, A., and Tong, N. Assessment of piezoelectric materials for roadway energy harvesting. Energy Research and Development Division Final Project Report, DNV KEMA Energy & Sustainability, Oakland, CA, 2014.
Ali, S. F., Friswell, M. I., and Adhikari, S., Analysis of energy harvesters for highway bridges. Journal of Intelligent Material Systems and Structures, Vol. 22, No. 16, 2011, pp. 1929‐1938
Xiong, H., Piezoelectric energy harvesting for public roadways, Ph.D. Dissertation, Virginia Polytechnic Institute and State University, Department of Civil Engineering, VA, 2014.
SolaRoad. Publications, http://en.solaroad.nl/publications/, accessed June 24, 2016.
Mehta, A., Aggrawa, N., and Tiwari, A., Solar Roadways-The future of roadways, International Advanced Research Journal in Science, Engineering and Technology, Vol. 2, Issue 1, May 2015.
Date Posted:06/14/2017
Date Modified:07/27/2017
Index Terms:Energy harvesting, Renewable energy sources, Economic benefits, Environmental impacts, Infrastructure, Emerging technology, Piezoelectricity, Sustainable development, California, State departments of transportation,
Cosponsoring Committees: 
Subjects    
Highways
Energy

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