The TE-Power-Bolt from Micropelt GmbH (Freiburg, Germany) is a voltage-adjustable thermal battery that uses excess heat to generate electrical energy for devices that consume only a few milliwatts of power, such as wireless sensor nodes. It is engineered with a microthermogenerator built into an M24 steel screw to harvest energy from surfaces and structures from 10° to 20°C over ambient temperature or directly from hot liquids. Output power can range from 0.2 mW to more than 15 mW and is voltage stabilized by an integrated dc-dc convertor, which can be set to fixed voltages between 1.2 and 5 V.
The component is designed to be an easy-to-deploy, self-sustaining energy supply that sticks out about 2.2 in. (55 mm) from its host’s warm or hot surface. By exposing the cylindrical 1.5-in. (38.1 mm)–diam aluminum heat sink to fresh air, the device acts as a “never-charge battery.” The power provided depends upon actual thermal conditions. Continuous airflow multiplies the output. Heat can also be obtained from liquids by screwing the bolt into the threaded hole of a hot liquid container or a pipe. The design is presently in the prototype phase.
“More low-power wireless sensor nodes and similar devices are being offered; however, most industries simply dislike batteries,” said Micropelt CEO Fritz Volkert. “The TE-Power-Bolt can work for them as an infinite maintenance-free battery for infrequent-duty-cycle applications.”