1. Wilburt Geng, Jonathan Mountford, Leah Schrauben
Energy Harvesting
Wilburt Geng, Jonathan Mountford, Leah Schrauben

2. Agenda What is energy harvesting? Classes of energy harvesting systems
Anatomy of an energy harvesting system
Common mechanisms and applications
Kinetic/inertial
Piezoelectric
Solar
Thermal
Summary
Questions

3. What is it, and why do we care?
Free energy!
PICTURES:

4. What is it, and why do we care?
Small amounts of energy from ambient sources
Power devices without connection to power grid
Low power, low energy, low maintenance
Little to no environmental footprint
Ideally allow for ‘perpetual operation’ embedded systems

5. Classes of Energy Harvesting Systems
Continuous
Low leakage, high capacity power container
Transitions between low power sleep and high power usage states
Always powered, always harvesting
Pulse
Unpowered until burst of energy is received and stored
Powers on and performs simple task using energy burst

6. Perpetually Powered Sensor
Ambient Energy:
Motion, light, heat
Energy Harvester
Energy Storage & Power Mgmt
Environment:
Temperature, position, status
Sensor(s)
Ultra Low Power Microcontroller
Low Power Transceiver
Adapted from:

7. Energy Harvesting Mechanisms
Kinetic/Inertial
Piezoelectric
Solar
Thermal

8. Energy Harvesting Mechanisms
Kinetic/Inertial
Piezoelectric
Solar
Thermal

9. Powering watches using natural motion
Application: Kinetic
Powering watches using natural motion
Utilizes natural motion of arm
Normal batteries need to be replaced regularly
Allows for more accurate quartz timing, without the need of replacement batteries
Doesn’t need to be rewound like a traditional watch

10. Application: Kinetic Inertia Energy Harvester
General concept to convert natural oscillations to electrical energy
Most applicable to wearable technology

11. Energy Harvesting Mechanisms
Kinetic/Inertial
Piezoelectric
Solar
Thermal

12. Applications: Piezoelectric
Monitoring pavement year-round deterioration
Concept proposed by Federal Highway Administration
Too many roads to easily monitor manually
Surface wear not indicative of internal wear
Higher upfront cost

13. Energy Harvesting Mechanisms
Kinetic/Inertial
Piezoelectric
Solar
Thermal

14. Measuring and displaying travel speeds of cars
Applications: Solar
Measuring and displaying travel speeds of cars
Allows autonomous monitoring of car speeds
Operation without difficult/tedious connections to power grid
Internal batteries allow for nearly continuous operation

15. Energy Harvesting Mechanisms
Kinetic/Inertial
Piezoelectric
Solar
Thermal

16. Applications: Thermal
Monitoring bearing health in airplane turbine engines
Running wires is expensive
Hard to reach places for humans
Limited space
Low maintenance

17. Summary Free, reusable energy Classes of harvesting systems:
Main energy harvesting mechanisms:
Kinetic
Piezoelectric
Solar
Thermal
Classes of harvesting systems:
Pulse
Continuous
Primarily used to power wireless sensors
Supplies low power, low efficiency, and low maintenance solutions

18. Resources General: Solar: Piezoelectric Kinetic: Thermal:
Solar:
Piezoelectric
Kinetic:
Thermal:

19. Questions?

20. appendix

21. Traditional Energy Generation
Transformation of chemical to electrical energy
Amount of fuel needed to generate 1 kWh of energy
Coal = 1.04 lbs
Natural gas = 0.01 Mcf
Petroleum = 0.07 gallons
Cheap, efficient, but requires connection to power grid

22. Why we are interested Ambient background energy usable energy
Easy energy for low power devices
Indefinite functionality without attachment to power grid or reliance on batteries

23. Application 6V 2W Solar Panel - $29 - Medium Solar Panel
4V 10µW Solar Panel - $ CPC1822
9VOC 4W Optimal TEG - $ TG LS
Solar Panel -

24. Kinetic Capture mechanical motion and converts it to electrical energy
Most applicable to wearable technology
Due to low power production, usually used in minimal power operations or to extend battery power

25. Kinetic: Watch

26. Kinetic: Basic Concept
A magnet is attached to a spring
Walking and other motions cause the magnet to bounce through a coil solenoid
The motion produces small amounts of current

27. Piezoelectric
Mechanical deformation of piezo crystal via tension or pressure generates electric charge imbalance
Applications in structural health/maintenance, product monitoring during transport, etc.

28. Solar Applications in space exploration and general power generation
Efficiencies between 15-20% for most solar panels
Doped silicon material converts solar to electrical power

29. Solar: In Depth Mechanism

30. Thermal Voltage output is proportional to temperature difference
5-8% efficiency
Thermal circuit:
Current = heat flow
Voltage = temperature
Heat Source:
Hot surfaces such as pipes, exhaust gas, direct sunlight, or human body
Heat Sink:
Typically convection to the air

31. Thermal: Why is it useful?
Usually produces < 1V
Boost converters bump voltage up
Supplies power to ultra-low power wireless sensors
Very little maintenance
Extremely reliable