Harvesting Ambient Environmental Energy for Wireless Sensor Networks: A Survey

Table 1

Comparison of power outputs from energy harvesting technologies.

Harvesting method	Power density	References
Solar energy—outdoors	15 mW/cm^3—bright sunny day	[18]
	0.15 mW/cm^3—cloudy day
Solar energy—indoors	10–100 μW/cm^2	[21]
Vibrations (piezoelectric—shoe inserts )	330 μW/cm^3	[25]
Vibrations (electrostatic conversion )	0.021 μW/mm^3—105 Hz	[26]
Vibrations (electromagnetic conversion )	184 μW/cm^3—10 Hz	[27, 28]
	306 μW/cm^3—52 Hz	[29]
Thermoelectric—5°C gradient	40 μW/cm^3	[30]
Wind flow	16.2 μW/cm^3—5 m/s	[31]
Acoustic noise	3 nW/cm^3—75 dB	[18]
	960 nW/cm^3—100 dB
Magnetic field energy	130 μW/cm^3—200 μT, 60 Hz	[32]