The lighting market can be a demanding taskmaster. It wanted battery-free, wireless lighting control, especially for large installations where battery management could be a real headache. But what could replace batteries? The energy source would need to meet a number of exacting criteria.  

It must be small enough to fit underneath a light switch. It also had to be cost competitive with battery-based systems. It must be able to function with minute amounts of energy and produce power with very little effort. And, the energy must be sufficient enough to bridge periods of inactivity, through the night, for example.

It was a tall order and required a fundamental breakthrough in the creation, storage and management of power. The result is miniaturized, ultra low power electronic harvesters that convert "unused environmental energy" into electricity.

What’s unused environmental energy? Solar, of course, but also pressure, temperature, vibration and motion. Even minute changes in these sources produce energy that can be harnessed for sending signals.

Four harvesting technologies power EnOcean switching, sensing and monitoring modules: electro-dynamic, thermoelectric, vibration and solar. 

An electro-dynamic coil and magnet energy harvester captures linear motion. The harvester is only 1.5 inches square and fits easily behind a light switch. It generates electricity every time someone actuates the switch, which requires about the same effort as that for traditional switches. The harvester is rated for at least 50,000 switching cycles without failure. Patented technology generates a relatively long-range signal using astonishingly small amounts of energy. 

A thermoelectric energy harvester produces electricity from small differences in temperature across a thermocouple. Employing the Seebeck effect, as little as three degrees K differential, combined with the world’s most efficient DC-DC converters, generate continuous current.

A vibration energy harvester converts mechanical stress—or vibration—imposed on a crystal or ceramic material into electricity. This is the piezoelectric effect and it can generate relatively large outputs.

Solar energy cells are well known as electricity generators. EnOcean uses thin layer solar cell technology in its modules to power light sensors for dimming and occupancy sensors to automatically switch off lights.