Introduction - Energy Harvesting Autonomous Sensor Systems - page 20

Autophagous
Structure-Power
Combustion

Biochemical

hermal
Gradient

Compressed
Gases

Wind Hydro

Electrochemical
Reaction

AC Rotary
Generator

hermoelectric
Generator

Artificial
Lighting

Solar
Radiation

Ocean Wave

AC Linear
Generator

Photovoltaic
Cell

Microwave
Radiation

Power/
Energy
Conditioning

Pressure

Energy
Storage

Electrical
Load

Antenna/
Rectenna

Piezoelectric
Element

Ambient Radio
Frequency Waves

Electrostatic
Generator

Induction Coil

Electromagnetic
Generator

Mechanical Vibration

Alternating B-Field:
Power Transmission
Lines

Wireless Power Transfer
via Strongly Coupled
Magnetic Resonances

FIGURE 1.15
Energy harvesting sources and their energy harvesters. (Adapted from J.P. Thomas, M.A. Qid-
wai, and J.C. Kellogg, “Energy scavenging for small-scale unmanned systems,” Journal of Power
Sources , vol.159, pp. 1494-1509, 2006 [27].)

renewable energy sources available at the specific application areas, like an
outdoor bright sunny day with a rich amount of solar energy, along a coastal
area with a lot of wind energy, on a bridge structure with travelling vehicles
and strong vibrations, and so on. In addition, there could also be the possibil-
ity of two or more energy sources available for harvesting at the same time.
As such, EH technology can provide numerous benefits to the end user, and
some of the major benefits of EH suitable for WSNs are stated and elaborated
in the following list [27, 28]. An EH solution can do the following:

1. Reduce the dependency on battery power. With the advancement of
microelectronics technology, power consumption of the sensor nodes
is decreasing, hence, harvested ambient/environmental energy may
be sufficient to eliminate the battery completely.
2. Reduce installation cost. Self-powered wireless sensor nodes do not
require power cable wiring and conduits; hence, they are very easy
to install and reduce the high installation cost.
3. Reduce maintenance cost. EH allows for the sensor nodes to function
unattended once deployed and eliminates service visits to replace
batteries.
4. Provide sensing and actuation capabilities on a continuous basis in
hard-to-access hazardous environments.