Toward Green IoT: Energy Solutions and Key Challenges

With the ongoing worldwide development of IoT, an unprecedented number of IoT devices imperatively consume a substantial amount of energy. IoT devices have been predicted to be the leading energy guzzler in Information and Communications Technology by 2020. In considering the finite amount of brown energy sources along with their potential harmful impacts to the climate and environment, we propose to leverage "free" green energy to power IoT devices and revolutionarily enable wireless charging of these devices. Specifically, we propose to green IoT in three steps, namely, ambient green energy harvesting, green energy wireless charging and green energy balancing, in which the latter step reinforces the former step to ensure the availability of green energy. We lay out the basic design principles for these three steps, shed some light on the solutions and present the corresponding challenges individually.