Develop a low power (battery driven) wireless device/sensor.
The Bluetooth Smart SensorTag is designed to shorten the design time for Bluetooth App development from months to hours by allowing App developers to write Apps that enable and use advanced sensors directly from a smartphone without any firmware or embedded software development.
Source: Simplelink SensorTag – TI.com
Taiyo Yuden Lithium Ion Capacitors: An Effective EDLC Replace
People might be encouraged to save water if they could see how much they are using. Build an in-line water meter that measures flow – and to make it easier to hook up, have it powered by the flow of water. Can it be wireless too?
If you want to do a project with wireless communication and don’t mind writing the communications software at a low level (or want to learn how to do this) check out the development system from TI. Note: this is much less capable than something like wifi, but much lower power (both Watts and processing power).
Some background information about battery choices for energy harvesting applications.
Use epaper and a very low power rf interface to create a programmable electronic sign (powered by solar cell or battery?). Can it be made completely wireless (no power or wired interface)?
Using energy harvesting techniques to get energy from insects to power onboard sensors/controls. http://t.co/9Mn2ZrGL
Many energy harvesting sources generate very low voltage and/or current. The link below is for a TI product that boosts the voltage to useful levels.