Putting together all the pieces now. Here is a complete Open Source Hardware (OSHW) Wireless Sensor Node (WSN) that energy scavenges. Have a Peltier thermo-electric generator resting on top of a 20W wirewound resistor and scavenging the energy from the waste heat of that resistor. The Peltier device then powers a Linear Technology LTC3108 chip (described here) which powers a wireless sensor node (WSN) that is built from a NXP LPC1114 MCU and a Atmel AT86RF212 800 MHz radio (described here). The wireless stack is the Chibi stack (described here). The WSN transmits data every 2 minutes, which gives the storage capacitor in the energy scavenger plenty of time to recover. The sleep state of the WSN draws about 25 micro-amps and the wake state when polling the sensors and the radio on draws about 11 ma. The radio is on for about a second every 2 minutes.
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The peltier device generates electrical power proportionate to the heat flow through the device. The power output can be increased then by blowing gently across the top surface of the peltier device which increases the convective heat loss on the top surface and increases the flow of heat through the device from the hot side where the resistor is generating heat to the top cool side where heat is lost convectively.