Comparison Of Energy Storage Technologies

Energy Storage Technical Parameters

Here, the comparison of energy storage technologies based on performance parameters are given here. The comparison of energy storage is given by considering following technical parameters.

• Round trip energy efficiency
• Discharge hours
• C rate
• Operating cost
• Cycle life
• Maturity of technology

Energy Storage Techniques by Parameter

 

Energy storage systems	Lead acid	Li-Ion	Nas*	Flow batteries	Flywheel	CAES*	PHS*
Round Trip Energy Efficiency (DC-DC)	70-85%	85-95%	70-80%	60-75%	60-80%	50-65%	70-80%
Discharge hours	2-6 hours	0.25-4 hours	6-8 hours	4-12 hours	0.25-4 hours	4-10 hours	6-20 hours
C Rate	C/6 to C/2	C/6 to 4C	C/8 to C/6	C/12 to C/4	C/4 to 4C	NA	NA
Cost range per energy available in each full discharge ($/ kWh)	100-300	250-800	400-600	400-1000	1000-4000	>15010	50-15016
Development & Construction Period	6 month – 1 years	6 month – 1 years	6 month – 1.5 years	6 month – 1.5 years	1-2 years	3-10 years	5-15 years
Operating Cost	High	Low	Moderate	Moderate	Low	High	Low
Estimated Space Required	large	Small	Moderate	Moderate	Small	Moderate	Large
Cycle life: # of discharges of stored energy	500-2000	2000-10,000+	3000-5000	5000-8000+	10,000	10,000+	10,000+
Maturity of Technology	Mature	Commercial	Commercial	Early to moderate	Early to moderate	Moderate	Mature

 

CAES – Compressed air energy storage

PHS – Pumped hydro storage

NAS – Sodium Sulphur batteries

Meaning of C Rate

The C rate is important parameter in the different energy storage system particularly in the electrochemical batteries. The C rate is an inverse measure of the rate over which a system can provide maximum rated power. The range of discharge duration is directly linked to the C rate. It is expressed in terms of 1C, 2C, C/2. C rate of 2C means that all it supplies all its stored energy in ½ hours whereas C/2 means it supply all its stored energy in 2 hours. Therefore, we can say that higher C rate can discharge at a higher maximum power than compare with lower C rate.  Higher C rate has higher power to energy ratio. High power application requires high C rate and short discharge duration.

Sodium based batteries, flow batteries, CAED and PHS are suitable for high energy and long duration applications. C rate is not used for CAES and PHS as the duration of energy storage is not limited by technology as in case of electrochemical batteries.

Cost

Levelized cost method is used to compare costs across different energy sources or technologies.

Space requirement and maturity of technology

Lithium-ion batteries find applications where space and weight is critical consideration. In terms of maturity, lead acid batteries have been around for over 100 years and very mature in terms of technology performance and manufacturing. The Lithium-ion batteries reached commercial maturity with multiple companies setting up GWh scale manufacturing plants.

Capital cost

Figure shows that the capital cost per cycle of some storage system decreases.