Multi-source energy harvesting and storage for floating wireless sensor network nodes

Wireless sensor networks are widely used for environmental monitoring in remote areas. They are mainly composed of wireless sensor nodes, usually powered by batteries with limited capacity, but are expected to work for extended periods. To overcome this limitation, many energy harvesting techniques are proposed to power the wireless nodes for prolonged operation. In this communication, a novel floating device with multi-source energy harvesting technology that can be used as a wireless sensor node is proposed. In addition to conventional solar panels, an energy harvesting technique based on thermoelectric generators exploiting thermal differences created between water surface and materials exposed to sunlight is proposed. Energy generated from photovoltaic and thermoelectric generators is combined to power the wireless sensor node. This floating device consumes 0.5Wh per day when used as a wireless sensor node for the collection of environmental data. It can operate on lakes for at least five days in conditions where there is no sunlight. During sunny days, the floating device can harvest 8.375Wh from solar panels and 0.425Wh from thermoelectric generation. In other words, the floating device harvests sufficient energy to be self-sustaining during sunny days.