(http://www.micropelt.com/applications/powergeneration.php)

Micropelt Power Bolt

Wireless and remote sensors, data loggers and other low power devices allow for deliberate distribution in the field at low initial cost. In most cases, however, they contain a battery which will run empty, causing inevitable cost for maintenance staff, access effort, material and environmentally compatible waste disposal.
Micropelt’s power bolt represents a new generation of remote power supply which provides uninterupted long term supply without a need for wiring up the device. A few milliwatts of continuous power are readily available from many warm or hot surfaces of industrial machinery or process equipment. The power bolt shows the concept of a maintenance-free thermal power supply. We look forward to supporting your custom product implementation.
Some measurement data can be found at the » thermogenerator datasheet (pdf document (386  KB)) on page 5 and 6 or at the » Power Bolt measurement datasheet (pdf document (64  KB)).

Power bolt

Power bolt sketch