As sensors and actuators are deployed in increasing numbers across greater distances, autonomous devices will become more ubiquitous. For systems that require longer life than a primary battery can deliver, Energy Harvesting offers a promising solution. Energy Harvesting (EH) is the process by which ambient energy is captured from one or more energy sources and stored for later use. It enables autonomous sensors or switches to perpetually run with little to no maintenance, eliminating the need for connection to an electric grid and overcoming limitations of a battery-only power source with limited energy storage. While the cost of buying and disposing batteries is a significant consideration, it’s the operational drain of maintenance that makes Energy Harvesting a particularly attractive solution for IoT. In this presentation: - Energy Harvesting solutions, including those that convert sources such as light, vibration, and heat into electricity (solar cells, piezoelectric devices, and thermoelectric generators). - Key considerations for an Energy Harvesting terminal, including optimal capacitor size. Linda Brabik, Founder/Organizer, IoT NY Meetup

1. Linda Drabik
Founder/Organizer IoT NY Meetup
meetup.com/iot-ny
@lindadrabik

2. Background
Wireless devices and sensors are proliferating.
As sensors and devices are deployed to remote areas
and/or in greater volume, Energy Harvesting is taking
on increasing relevance.
It’s an alternative to the costly maintenance of a
battery supply.
Energy Harvesting for IoT

3. Context
• To tackle the whole picture for sensors, need to consider
other parts of the system:
– Energy storage
– Energy harvester
– Computer platform/algorithms
• Peak power requirements can exceed the power generated by
EH. Need to consider options for energy sources:
• Sensor uses power only when available (non-continuous operation)
• Charge controller used to balance battery charging and system power (can
also have an optional battery in addition to the rechargeable battery)
• No battery and use alternative controller (e.g. DC-DC converter in solar)
Energy Harvesting for IoT

4. Industries
• Industrial
– Wireless Sensor Networks
– Power generation
• Autos- modern car has more than 100 sensors
• Medical- more than 20B disposable sensors shipped per year
• Growing fleets of sensors across a range of use cases and
industries (e.g. AgTech)
Energy Harvesting for IoT

5. Energy Harvesting
• Energy Harvesting (EH) is the conversion of ambient energy
from the environment to electricity at small scale
• Can range from microwatts for wireless sensors to kilowatts
for vehicles and buildings
• According to IDTechEx
– The market for transducers and power conditioning is estimated at
over $12 billion by 2025
– For the coming decade, the largest addressable value market is in
range of one watt to 10 kW
Energy Harvesting for IoT

6. Energy Harvesting Methods
1. Photovoltaic - Light
2. Electrodynamic – Electromagnetic Field Change
3. Thermoelectric – Heat
4. Piezoelectric – Mechanical Strain
5. Other Methods & Emerging Methods
Energy Harvesting for IoT

7. Photovoltaic - Light Energy
• Energy source: Indoor and outdoor light
• Method: via a pn junction (majority use case) or
photoelectrochemical reaction (Dye Sensitized Solar Cells
DSSC)
• Common applications: IoT beacons, home automation,
wearables, drones, wireless sensors
• Considerations: spectral distribution (outdoor- wide
distribution, indoor- narrow distribution), varying angles,
intensity, distance based on season
Energy Harvesting for IoT

8. Electrodynamic – Electromagnetic Field Change
• Energy Source: movement, vibrational, rotational or linear by
means of electromagnetic machines
• Method: Energy derived from interactions of electric currents
with magnets, with other currents, or with themselves.
• Common Applications: dynamos, alternators and electric
vehicle traction motors working backwards
• Considerations: Harvesting from different motions, designing
for different excitation profiles (vibration, flow, rotation; 1D,
2D, 3D; continuous, oscillatory, pendulum)
Energy Harvesting for IoT

9. Thermoelectric – Heat Energy
• Energy source: temperature differences
• Method: Seebeck effect - conversion of a temperature
differential into electricity at the junction of two materials
• Common applications: condition monitoring in industrial
environments, smart metering, vehicles
• Considerations: operation in high temperatures or corrosive
environments, increased safety demands, form factor (thin,
flexible, or even stretchable)
Energy Harvesting for IoT

10. Piezoelectric – Mechanical Strain
• Energy Source: mechanical strain (e.g. human motion, low-
frequency seismic vibrations, and acoustic noise)
• Method: capturing movement by means of materials that
generate electricity when acted on by a mechanical force
• Common applications: still considered emerging; self-
powered electronic switch (battery-less doorbell), DARPA
exploring harnessing energy from leg and arm motion, shoe
impacts, and blood pressure for low level power to
implantable or wearable sensors.
• Considerations: typically operates in AC requiring time-
varying inputs at mechanical resonance to be efficient.
Energy Harvesting for IoT

11. Other Less Common Methods of EH
• Capacitive (change capacitor dimensions by force)
• Triboelectric (friction)
• Magnetostrictive (movement of magnetostrictive materials)
• Pyroelectric (temperature change)
• Ambient radiation (antenna/rectifier)
• Emerging: radio waves (3G/4G network)
Energy Harvesting for IoT

12. Maturity and Applications of EH Methods
Maturityofadoptedsolutions
Maturity
Low
Photovoltaic
Electrodynamic
Thermoelectric
Piezoelectric
Wristwatches, garden lights,
flashlights, etc.
Vehicles & trains-
regenerative breaking
Wireless building controls &
actuators
Mobile phones, laptops,
automotive sensors, wireless
networks
EH Method Applications
High
Energy Harvesting for IoT

13. Challenges in EH
• Translating theoretical power output to real life actual power generated is
plagued with inefficiencies that hinder proliferation.
• Power output remains a significant challenge for consumer electronics
applications as smart phones, tablets, laptops and other portable devices
have requirements of average (not peak) power of a minimum of 10mW.
• The limited amount of surface area on these devices coupled with low
efficiencies of energy harvesting devices and operation in non-optimal
environments compromises power output.
• Unless significant advances are made in both ultra low power electronics
and harvester power output in order to reach a point of convergence,
integration of energy harvesting in consumer electronics will remain
unviable.
Source: IDTechEx
Energy Harvesting for IoT

14. Questions
Energy Harvesting for IoT