  Unmanned Aerial Vehicles (UAVs) present a promising advanced technology that
can enhance people life quality and smartness of cities dramatically and
increase overall economic efficiency. UAVs have attained a significant interest
in supporting many applications such as surveillance, agriculture,
communication, transportation, pollution monitoring, disaster management,
public safety, healthcare, and environmental preservation. Industry 4.0
applications are conceived of intelligent things that can automatically and
collaboratively improve beyond 5G (B5G). Therefore, the Internet of Things
(IoT) is required to ensure collaboration between the vast multitude of things
efficiently anywhere in real-world applications that are monitored in
real-time. However, many IoT devices consume a significant amount of energy
when transmitting the collected data from surrounding environments. Due to a
drone's capability to fly closer to IoT, UAV technology plays a vital role in
greening IoT by transmitting collected data to achieve a sustainable, reliable,
eco-friendly Industry 4.0. This survey presents an overview of the techniques
and strategies proposed recently to achieve green IoT using UAVs infrastructure
for a reliable and sustainable smart world. This survey is different from other
attempts in terms of concept, focus, and discussion. Finally, various use
cases, challenges, and opportunities regarding green IoT using UAVs are
presented.
