Table 1 Power densities of typical energy harvesters.
| Energy source | Characteristics | Efficiency | Power density |
|---|---|---|---|
| Light | Outdoor | 10–25% |
100 mW/
|
| Indoor |
100  W/
| ||
| Thermal | Human | 0.1% |
60  W/
|
| Industrial | 3% |
10 mW/
| |
| Vibration | Hz-Human | 25–50% |
4  W/
|
| kHz-Machines |
800  W/
| ||
| Radio | GSM 900 MHz | 50% |
0.1  W/
|
| frequency | WiFi 2.4 GHz |
0.001  W/
|