Energy
is everywhere in the environment surrounding us — available
in the form of thermal energy, light (solar) energy, wind
energy, and mechanical energy. However, the energy from these
sources is often found in such minute quantities that it cannot
supply adequate power for any viable purpose. In fact, until
recently, it has not been possible to capture such energy
sufficiently to perform any useful work.
This
scenario is about to change.
Energy
Harvesting is the process of capturing minute amounts of energy
from one or more of these naturally-occurring energy sources,
accumulating them and storing them for later use. Energy-harvesting
devices efficiently and effectively capture, accumulate, store,
condition and manage this energy and supply it in a form that
can be used to perform a helpful task. Similarly, an Energy
Harvesting Module is an electronic device that can perform
all these functions to power a variety of sensor and control
circuitry for intermittent duty applications.
Why
Energy Harvesting?
Advanced
technical developments have increased the efficiency of devices
in capturing trace amounts of energy from the environment
and transforming them into electrical energy. In addition,
advancements in microprocessor technology have increased power
efficiency, effectively reducing power consumption requirements.
In combination, these developments have sparked interest in
the engineering community to develop more and more applications
that utilize energy harvesting for power.
Energy
harvesting from a natural source where a remote application
is deployed, and where such natural energy source is essentially
inexhaustible, is an increasingly attractive alternative to
inconvenient wall plugs and costly batteries. This essentially
free energy source, when designed and installed properly,
is available maintenance-free and is now available throughout
the lifetime of the application. Such systems can be more
reliable than wall plugs or batteries.
In
addition, energy harvesting can be used as an alternative
energy source to supplement a primary power source and to
enhance the reliability of the overall system and prevent
power interruptions.
Energy
Harvesting Applications
Many
real life applications using energy harvesting system power
are now practical. Wireless sensor network systems such as
ZigBee systems often benefit from energy harvesting power
sources. For example, when a wireless node is deployed at
a remote site where a wall plug or a battery is either unreliable
or unavailable, energy harvesting can augment or supply power.
In another example, a remote control node running on energy
harvesting can be implemented as a self-powered electronic
system. And in yet other situations, multiple energy sources
can be used to enhance the overall efficiency and reliability
of any system.
Common
Sources of Energy Harvesting
- Mechanical
Energy – from sources such as vibration, mechanical
stress and strain
- Thermal
Energy – waste energy from furnaces, heaters, and
friction sources
- Light
Energy – captured from sunlight or room light via
photo sensors, photo diodes, or solar panels
- Electromagnetic
Energy – from inductors, coils and transformers
- Natural
Energy – from the environment such as wind, water
flow, ocean currents, and solar
- Human
Body – a combination of mechanical and thermal energy
naturally generated from bio-organisms or through actions
such as walking and sitting
- Other
Energy – from chemical and biological sources
It
is important to note, that all these energy sources are virtually
unlimited and essentially free, if they can be captured at
or near the system location.
Key Components
of an Energy Harvesting System
An
energy harvesting system generally requires an energy source
such as vibration, heat, light or air flow and three other
key electronic components, including:
- An
energy conversion device such as a piezoelectric element
that can translate the energy into electrical form
- An
energy harvesting module that captures, stores and manages
power for the device
- An
end application such as a ZigBee-enable wireless sensor
network or control and monitoring devices.
Optional
Key Components of an Energy Harvesting System
In
addition to the three key components listed above, in certain
applications there can be additional key components that would
be vital to the functioning of an energy harvesting system:
- An
electronic interface device or module, such as a low voltage
step up booster module, to condition the energy captured
from a low voltage source (less than 500mV) and power the
energy harvesting module
- A supplementary
energy storage device, such as thin-film batteries, ultra
capacitors, and super capacitors
- An
energy or power management module that will further regulate
and condition the power output from the supplementary energy
storage devices
Keep in
mind that all these optional key components require extra
energy to function, and thus reduce the system?s overall energy
capture efficiency and add to the bulk and cost. The cost
vs. benefit trade-off of these additional components must
be carefully evaluated in any particular energy harvesting
system.
Note:
If your company produces an energy harvesting product and
has a datasheet and pricing information, please submit such
information to be added to this website by contacting ehadmin@energyharvesting.net
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