Presentation on theme: "Montek Singh COMP790-084 Sep 20, 2011. Basics of energy harvesting ◦ why must some systems harvest energy? ◦ where do you scavenge energy from? Introductory."— Presentation transcript:
Montek Singh COMP Sep 20, 2011
Basics of energy harvesting ◦ why must some systems harvest energy? ◦ where do you scavenge energy from? Introductory case studies ◦ Philips ◦ CEA-LETI Next class: ◦ More case studies ◦ Challenges and Benefits ◦ Open questions
What is energy harvesting? ◦ no power supply, no batteries ◦ somehow scavenge energy from physical env What type of systems must harvest energy? ◦ hard to replace/recharge batteries ◦ hard to have batteries at all ◦ examples?
Where do you harvest energy from? ◦ ambient light/solar: using photovoltaic cells range: 0.1W/sq cm direct sun; 0.1mW/sq cm indoors silicon solar cells only 5-20% efficiency; 0.6V/cell ◦ temperature gradients: using thermoelectric generators Seebeck effect turns temp gradients into electricity few hundred mV with a few Kelvin gradient
Where do you harvest energy from? (contd.) ◦ Vibration energy: using electrostatic transducers below 100Hz ◦ RF power: using tuned antenna if 2W emitted by reader: 0.5-2mW harvested at 1-2 meters distance used in RFID tagging ◦ Inertial kinetic energy: from human body using knee brace, backpack, etc. Seiko automatic watches!
Where do you harvest energy from? (contd.) ◦ Biosensing: use blood glucose! ◦ Acoustic vibrations: using piezoelectric transducers ◦ Wind energy… ◦ Tidal/water waves…
Contactless smart card ◦ basic architecture
Why asynchronous? ◦ async overall consumes less energy ◦ async has better current/power profile: more spread ◦ async has no fixed clock rate