Energy Harvesting Technology and Applications

1. Team 2 AFRL WSN Health Diagnostic Energy Harvesting Technology and Applications

2. Introduction • What is energy harvesting? • The process by which energy is derived from external sources • Why use energy harvesting? • Renewable source • Allows for remote charging in applications

3. Energy Harvesting Background • Energy harvesters provide a very small amount of power for low-energy electronics • The energy source for energy harvesters is present as ambient background and is free • As opposed to large-scale energy generation which costs money

4. Why Use Energy Harvesting Technology? • Converted energy can be stored in a capacitor for short-term use or a battery for long-term use. • Allows for the battery (or a charger) to be taken out of the equation of an application since it sources energy from the environment

5. Ways to Harvest Energy • Materials • Piezoelectric • Pyroelectric • Photovolatics • Other • Kinetic Energy • RF Energy

6. Piezoelectric Effect (Pressure) • Converts mechanical strain to electric current • Produces power on the order of mW • Useful for small applications • Handheld devices • Light bulbs • Human Motion • Acoustic Noise • Vibrations • Pressure

7. Pyroelectric Effect • Converts changes in temperatures to electric current • Stable for temperatures above 1200 ⁰C • High thermodynamic efficiency • Used in • Power Plants • Automobiles

8. Other Kinetic Energy • Converts human and/or natural motion into electric current • Found in • Wind Turbines • Ocean Wave Buoys • Human Motion

9. Photovoltaic Effect • Also known as solar power • Converts solar radiation into DC • Found just about everywhere and gaining more popularity

10. RF Energy Harvesting • Converts RF signal energy into DC power • RF energy is available in a wide array of frequency bands due to everyday technologies • Cell Phones • Radio Towers • WiFi Routers • Laptops • TV Signals • Only a tiny amount of power can be harvested, good for low power applications (Ex: A WiFi router can transmit 50-100mW) • Usually very short distance, however Powercast demonstrated energy harvesting at 1.5 miles

11. Energy Harvesting and Wireless Sensor Networks Our project uses RF power harvesting technologies

12. Why RF Energy Harvesting? • Ultra-low power, battery free applications • Perfect for wireless sensor networks

13. RF Power Sources • Intentional Sources • Powercast utilizes a direct RF energy source, dedicated to providing RF energy for harvesting • Anticipated Ambient Sources • Routers, cell phone transmitters • Unknown Ambient Sources • Microwave radio links, mobile radios

14. A Closer Look at a Powercast Sensor Node • Module Components & Features • Powercast P2110 Powerharvester™ Receiver • MCU: Microchip PIC24 XLP • Radio module • Microchip MRF24 (802.15.4) • RF Powerharvester • System power: 3.3V • Capacitor • 50mF (as low as 3300uF) • Discrete sensors: Temp, Humidity, Light • Wireless protocol: MiWi™ P2P

15. Sensor Module System Voltage

16. Powercaster Transmitter • Center Frequency = 915MHz • Intentional RF Source • Directional Antenna

17. Complete RF Energy Transmission

18. P2110 Powerharvester Receiver Efficiency

19. Packet Frequency vs. Distance from RF Source

20. Powercast Sensor Performance Overview • Optimized RF Powerharvesting for the transmitter frequency • RF Powerharvesting allows for remote placement of sensor nodes • Great performance due to a design that focuses on minimizing power consumption in each node • Proprietary wireless protocol

21. Conclusion • Power harvesting technologies are everywhere and efficiencies are vastly improving • Simply look at solar efficiencies • Most of the world’s energy in the future will be generated using power harvesting technologies