Type of energy storage

Power density PDr (W/kg)

Energy density EDr (Wh/kg)

Power level MW

Time (hours)

Ultra capacitor

20000

30

<1

10/3600

Lithium-ion battery

300 - 800

150 - 250

<1

4

lead acid battery

200 - 400

25 - 30

0.001 - 10

4

Fly wheel

150 - 3000

5 - 80

0.1 - 10

0.25

Flow battery

5 - 40

90 - 400

0.01 - 100

4