1. Energy Harvesting Thomas Vermeer 3/25/09 Embedded Systems

2. Agenda What is Energy Harvesting? Common Energy Harvesting Systems Energy Sources Energy Storage Optimization Methods

3. Energy Harvesting What is Energy Harvesting? Energy Harvesting is a way of powering an embedded system by ‘harvesting’ energy from the environment

4. Energy Harvesting Common Energy Harvesting Systems

5. Energy Harvesting Common Energy Harvesting Systems Car Tire Pressure Monitors

6. Energy Harvesting Common Energy Harvesting Systems Wireless Weather Stations

7. Energy Harvesting Common Energy Harvesting Systems Implantable Medical Devices

8. Energy Harvesting Common Energy Harvesting Systems Traffic Alert Signs

9. Energy Harvesting Common Energy Harvesting Systems Mars Rover

10. Energy Harvesting Two Design Goals: Choose very low power electronics Harvest and store energy efficiently

11. Energy Harvesting Sources of Energy:

12. Energy Harvesting Sources of Energy: Solar

13. Energy Harvesting Sources of Energy: Mechanical

14. Energy Harvesting Sources of Energy: Thermal

15. Energy Harvesting Sources of Energy: Electromagnetic

16. Energy Harvesting Energy Storage

17. Energy Harvesting Energy Storage Option 1: Traditional Rechargeable Batteries

18. Energy Harvesting Energy Storage Option 1: Traditional Rechargeable Batteries Inefficient charging – lots of energy converted to heat

19. Energy Harvesting Energy Storage Option 1: Traditional Rechargeable Batteries Inefficient charging – lots of energy converted to heat Limited number of charging cycles

20. Energy Harvesting Energy Storage Option 2: Traditional Capacitors

21. Energy Harvesting Energy Storage Option 2: Traditional Capacitors Efficient charging

22. Energy Harvesting Energy Storage Option 2: Traditional Capacitors Efficient charging Limited Capacity

23. Energy Harvesting Energy Storage Option 3 – Best Option: Super Capacitors

24. Energy Harvesting Energy Storage Option 3 – Best Option: Super Capacitors Efficient charging and high capacity

25. Energy Harvesting Super Capacitors Small Size High Efficiency Very high capacity (1-100 Farads) ~20% capacity drop per decade

26. Energy Harvesting Maximizing Energy Stored What if our system charges at 5V?

27. Energy Harvesting Maximizing Energy Stored We could charge system when Vin>5V, or for about 5 hours/day

28. Energy Harvesting Maximizing Energy Stored But look at all this wasted energy!

29. Energy Harvesting Maximum Power Point Tracking

30. Energy Harvesting Maximum Power Point Tracking Uses buck/boost voltage regulators

31. Energy Harvesting Maximum Power Point Tracking Uses buck/boost voltage regulators “Buck” the voltage down at peak times, supplying 5V with high current

32. Energy Harvesting Maximum Power Point Tracking Uses buck/boost voltage regulators “Buck” the voltage down at peak times, supplying 5V with high current “Boost” the voltage up at lower times, supplying 5V with low current

33. Energy Harvesting Autonomous Maximum Power Point Tracking Preprogrammed regulators Feedback circuits Inexpensive Easy to implement Low power overhead

34. Energy Harvesting Active Maximum Power Point Tracking Uses MCU or DSP Difficult implement High power overhead Can be counterproductive

35. Energy Harvesting Any Questions?