Energy Harvesting Technology and Applications

Team 2AFRL WSN Health Diagnostic

Introduction What is energy harvesting?

The process by which energy is derived from external sources

Why use energy harvesting?Renewable sourceAllows for remote charging in applications

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 freeAs opposed to large-scale energy

generation which costs money

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

Ways to Harvest Energy

Materials Piezoelectric Pyroelectric Photovolatics

Other Kinetic Energy RF Energy

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

Pyroelectric Effect

Converts changes in temperatures to electric current

Stable for temperatures above 1200 C⁰

High thermodynamic efficiency

Used in Power Plants Automobiles

Other Kinetic Energy

Converts human and/or natural motion into electric current

Found in Wind Turbines Ocean Wave Buoys Human Motion

Photovoltaic Effect

Also known as solar power

Converts solar radiation into DC

Found just about everywhere and gaining more popularity

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 LaptopsTV 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

Energy Harvesting and Wireless Sensor Networks

Our project uses RF power harvesting technologies

Why RF Energy Harvesting?

Ultra-low power, battery free applications Perfect for wireless sensor networks

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

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

Sensor Module System Voltage

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

Complete RF Energy Transmission

P2110 Powerharvester Receiver Efficiency

Packet Frequency vs. Distance from RF Source

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

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