Energy harvesting based on water evaporation-induced electrokinetic streaming potential/current in porous carbonized carrots

Abstract

The use of ambient evaporation for power generation has emerged as a brand-new concept of renewable energy harvesting in recent years. However, the low output level, high cost of raw materials and complex preparation impede its development. In this work, carbonized freeze-dried carrot pieces (CFCPs), as a kind of biomass carbon materials, are proposed as a three-dimensional micro-scale porous network to generate electricity (electrokinetic streaming potential/current) via the evaporation-induced water flow. The evaporation and the capillary force induce continuous water flows within the electrically charged hydrophilic porous CFCP and then produce the streaming potential/current. A single CFCP in the ambient environment can output a stable open-circuit voltage (OCV) of up to VOC ∼0.8 V, a short-circuit current (SCC) of ISC ∼ tens of microamps, and a maximal power density of ∼1.7 μW/cm2. Moreover, a commercial calculator can be powered by a serial connection of four CFCPs (approximately one carrot). This study provides a new perspective on renewable energy harvesting, promotes the use of biomass materials as energy harvesting media, and promises the development of environment-benign power generation systems using ambient evaporation.