Converting Road Kinetic Energy to Electricity for Smart City Infrastructure

Zabihi, Niloufar and Saafi, Mohamed (2022) Converting Road Kinetic Energy to Electricity for Smart City Infrastructure. PhD thesis, Lancaster University.

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Abstract

Smart cities are becoming a reality around the world. They rely on smart infrastructures that use sensors, signals, and telecommunication devices for data collection, such as air pollution, traffic, health monitoring of the infrastructures, and communication. The collected data is employed to improve and optimize the performance of the urban facilities, resources, and buildings, which eventually can optimize the costs and the efficiency of the city. The necessary devices of smart cities such as the Internet of Things (IoT) and sensors are able to communicate, exchange data, and optimize the performance of the city’s facilities. These devices (sensors, signals and IoT) need extra power sources to operate, which implies the demand to have an extra power source for smart cities infrastructure. On the other hand, the transportation is one of the major energy-consuming sectors in the world. In the UK in 2020, the transport sector accounted for 40.5 million tonnes of oil equivalent energy consumption, and a large portion of it is consumed in roads transport. From this significant amount of energy, a large share of it is wasted as kinetic and thermal energy. The surface of the roads experience excessive vibrations each time a car passes, and the high temperature of the surface of the road is a well-known phenomenon. This research revolves around the wasted energy in the roadways and attempts to recover a part of this waste by converting it to electricity as a new source for powering the sensors, signalling devices and potentially lighting infrastructure in smart cities. The first step of this study was designing a compact mechanical energy harvester based on the crank mechanism. Following the design, the performance of the mechanism was checked using motion and finite element analysis. Through motion analysis, the critical factors to be studied experimentally were identified. In the next step, the crank's components and the other parts of the system were assembled, and the motion analysis and FEA were verified. The assembled prototype was tested under mechanical loads resembling the real field applications. The testing scenarios were nine different combinations of displacement magnitude and displacement speed of the top plate. In the next phase of the experimental study, the harvester's performance was improved using a different set of springs (the supporting system of the harvester). Then, a similar experimental plan was conducted on the harvester with the new sets of springs. The focus of the experiments in all phases is the electrical output of the harvester. Next, a financial and technical feasibility study was conducted based on the performance of the harvester. The crank-based road energy harvester performs well under mechanical loads and can convert the top plate's vertical movements to rotation. In this system, all the components are bolted. Therefore, it has the advantage of mitigating any risk of backlash or mismatch between the components and is more compatible with higher driving speeds, as opposed to the existing mechanical road harvesters. Based on the results and the feasibility analysis, the average energy output of 90 crank-based energy harvesters with the current design in one day can generate enough power for illuminating one streetlamp, and more than 90 LED signals, and over 180 outdoors air quality meters, which are essential elements of smart cities, for one day. In addition, the system has a more compact design and provides a smooth ride for the drivers as the maximum vertical displacement is limited to a maximum of 25 mm.