A hybrid wind and rainwater energy harvesting system for applications in sea-crossing bridges

Abstract

As one of the essential types of clean energy, renewable energy has great potential to achieve the self-powered of wireless sensor. The health of the bridge depends mainly on the lifetime of the sensor. Therefore, it is of great significance to use renewable energy to achieve self-powered application of bridges. In this paper, a hybrid wind energy and rainwater energy harvester (WEREH) system for a self-powered sea-crossing bridge is presented. The proposed WEREH is installed on the drainpipe on the pier of the sea-crossing bridge. The system mainly includes three modules: energy collection module, energy conversion module, and energy storage module. The energy collection module is composed of S-rotor and water wheel. The energy conversion module is made up of a PVDF film array and magnet array. Electric energy can be obtained by the methods in which the PVDF films strike the adjustable plate and the changing magnetic field excites the coil. When only windy weather or only rainy weather is available, the S-rotor and water wheel are used to collect wind energy or rainwater energy, respectively. When it is windy and rainy mixed weather, the energy conversion module can keep working via one-way bearings. What is more, the S-rotor and water wheel can be flexibly combined with the energy conversion module to collect wind energy and rain energy, respectively. Finally, the power storage module stores the electricity by supercapacitors and the electric energy will be used to supply power for the low-power sensor of the sea-crossing bridge. Both simulations and experiments are performed to validate the feasibility and suitability of the system. Experimental results show that maximum output power can reach 2196.7 μWat the wind speed of 12 m/s and 245.76 μWat the flow rate of 18 L/min. Under the same condition, the maximum electric energy of the WEREH can reach 8659.76 μJin windy weather and 811.35 μJin rainy weather in a sweep process (6s). According to potential energy analysis, the annual electricity generated by each WEREH device can supply power for a displacement sensor (KTC1/LWH) for at least 239.95 days and a low-power temperature sensor (Si705x) for 254809.18 days at most.