EnergyScavenging

EnergyScavenging - Shad Roundy Shad Roundy 2/19/2003...

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Unformatted text preview: Shad Roundy Shad Roundy 2/19/2003 University of California, Berkeley Energy Scavenging for Wireless Sensor Nodes with a Focus on Vibration-to-Electricity Conversion Shad Roundy Motivation and Objective Wireless sensor and computing networks As people find more ways to incorporate these inexpensive, flexible and infinitely customisable devices into their lives, the computers themselves will gradually disappear into the fabric or our lives. Bill Gates in The Economist, Dec. 2002. Small, low power, low cost, low data rate wireless platforms are being developed in many places Shad Roundy Motivation and Objective Effective, long term, power supplies are lacking Example: At an average power consumption of 100 W, you need more than 1 cm 3 of lithium battery volume for 1 year of operation. The pervasiveness and near-invisibility of computing will be helped along by new technologies such as inductively powered computers that rely on heat and motion from their environment to run without batteries. Bill Gates in The Economist, Dec. 2002. Goal: To investigate power scavenging technologies that can provide an average of 100 W/cm 3 indefinitely. Shad Roundy Comparison of Power Sources Power Density ( W/cm 3 ) 1Year lifetime Power Density ( W/cm 3 ) 10 Year lifetime Source of information Solar (Outdoors) 15,000 - direct sun 150 - cloudy day 15,000 - direct sun 150 - cloudy day Commonly Available Solar (Indoors) 6 - office desk 6 - office desk Experiment Vibrations 100 - 200 100 - 200 Experiment and Theory Acoustic Noise 0.003 @ 75 Db 0.96 @ 100 Db 0.003 @ 75 Db 0.96 @ 100 Db Theory Daily Temp. Variation 10 10 Theory Temperature Gradient 15 @ 10 C gradient 15 @ 10 C gradient 1997 Shoe Inserts 330 330 Starner 1996 Shenck & Paradiso 2001 Batteries (non-recharg. Lithium) 89 7 Commonly Available Batteries (rechargeable Lithium) 13.7 Commonly Available Gasoline (micro heat engine) 403 40.3 Mehra et. al. 2000 Fuel Cells (methanol) 560 56 Commonly Available Comparison of Energy Scavenging Sources Yellow area denotes sources with a constant power output. Blue area denotes sources with a fixed amount of energy . Shad Roundy Batteries, Solar, and Vibrations Continuous Power / cm 3 vs. Life Several Energy Sources 1 10 100 1000 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Years microWatts Lithium Alkaline Lithium rechargeable Zinc air NiMH Solar Vibrations Shad Roundy Merits of Batteries, Solar, Vibrations If outdoor sunlight, or relatively intense indoor light it available, solar cells appear to be the best alternative.- Solar cells are a mature technology and a mature research area. If projected lifetime is longer than 1 year, vibrations offer an attractive alternative for certain environments. It was therefore decided to pursue research into the conversion of vibrations to electricity. Shad Roundy Vibrations Whats available?...
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This note was uploaded on 12/27/2011 for the course CMPSC 290h taught by Professor Chong during the Fall '09 term at UCSB.

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EnergyScavenging - Shad Roundy Shad Roundy 2/19/2003...

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