Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Enhanced energy-generation performance of a landfilled road-capable piezoelectric harvester to scavenge energy from passing vehicles Seong Do Hong a,1 , Kyung-Bum Kim a,1 , Wonseop Hwang a,1 , Yoo Seob Song b , Jae Yong Cho a , Se Yeong Jeong a , Jung Hwan Ahn c , Gi-Hoon Kim d , Haimoon Cheong d , Tae Hyun Sung a, ⁎ a Department of Electrical Engineering, Hanyang University, Seoul 133-791, Republic of Korea b Department of Civil Engineering, The University of Texas Rio Grande Valley, Edinburg, TX 78539, USA c Korea Electric Power Research Institute, 105, Munji-ro, Yooseong-gu, Daejeon, Republic of Korea d Korea Expressway Corporation Research Institute, 208-96, Dongbu-daero 922 Beon-gil, Dongtan-myeon, Hwaseong, Republic of Korea ARTICLE INFO Keywords: Landfilled module Road-capable piezoelectric energy harvester Autonomous emergency lighting Pavement technology Energy harvesting road ABSTRACT We demonstrate the use of a road-capable piezoelectric harvester (RCPH) with improved maintenance and power-generation characteristics. The RCPH obtained its ingress and moisture protection system rating (IP 66) through a new housing system used to evaluate its waterproof performance. Finite element simulations were performed to identify the proper depth (1, 3, or 5 cm) under an actual road for its placement to achieve increased output power. The highest von Mises stress value was measured by the 1 cm landfilled module (1LFM). The RCPH was installed under a test road and was tested with the use of the exposed and landfilled method to compare output power levels. Correspondingly, the output voltage and output power of the 1LFM were higher the exposed module. When a minivan drove over the 1LFM at 90 km/h, an output voltage of 18 V max and an output power of 1150 mW max (power density: 1.15 mW/cm 2 ) were measured at a load resistance level of 910 Ω. In a test road environment, the electrical energy generated by the 1LFM was sufficient to illuminate four deli- neators for 40 s. This system could be used on actual roads by connecting the piezoelectric modules to an emergency lighting that can be powered by the electricity generated by the module. 1. Introduction Energy-harvesting technology currently uses resources that include the vibration [1–3], solar [4,5] and heat [6,7] energy sources around us. Harvesting techniques that utilize piezoelectric materials can be used to collect ambient vibration energy. Important examples include harvesting techniques that detect and collect energy from vibrations owing to various types of mechanical equipment, buildings, roads, railways and automobiles [8,9]. The increasing demand for auto- mobiles and changes in transportation systems with a focus on high- ways has led to an increase in the available vibration energy [10–13]. The development of a piezoelectric energy harvester system that can be coupled to a road can help utilize the associated vibration energy. The state of California in the USA has transformed a state highway into an energy-harvesting highway using piezoelectric materials [14]. Re- cently, an energy-absorbing pavement system that consisted of a con- ductive asphalt layer and a piezoelectric material layer was designed and its power-generation characteristics were verified. Accordingly, an output voltage of 7.2 V was achieved with a piezoelectric module that was used in actual roads [15]. In another study, the feasibility of the road energy collection was analyzed systematically and a light-emitting diode (LED) traffic signal indicator lamp was constructed based on a piezoelectric module [16]. A piezoelectric energy-harvesting module based on polyvinylidene fluoride (PVDF) that exhibited power-gen- eration characteristics of up to 200 mW was also demonstrated [17]. In addition, asphalt pavement technology necessary for the installation of piezoelectric modules has been used recently to convert vibrational energy from roads [16,18–20]. However, the main drawbacks are the low energy production and the lack of a sustainable energy supply. Further research is imperative to improve the performance of piezo- electric energy modules [21,22]. In this study, a piezoelectric generator was installed at different depths under the road surface to increase the generated power from the milliwatt to watt ranges. In its evaluation on a test road, a maximum output of 1.1 W from a single module was measured after the application of a packing technique using a compo- site material. Even in dark conditions, the self-generated electricity https://doi.org/10.1016/j.enconman.2020.112900 Received 17 January 2020; Received in revised form 17 April 2020; Accepted 24 April 2020 ⁎ Corresponding author. E-mail address: sungth@hanyang.ac.kr (T.H. Sung). 1 Contributed equally to this work. Energy Conversion and Management 215 (2020) 112900 Available online 27 April 2020 0196-8904/ © 2020 Elsevier Ltd. All rights reserved. T