1. SESSION TITLE Dr. H. Pirouz Kavehpour
Professor & Vice Chair, Mech. & Aerospace Eng.
University of California, Los Angeles
USA

2. Energy Storage System for Solar Energy Systems from Utility Scale to Small Scale
Over-rated and Under-rated Parameters and Alternatives to Batteries

3. Applications of energy storage
Why Storage is Needed
Applications of energy storage
Lack of availability
High cost of energy at different time (Energy business)
Renewables

4. Agenda Energy Storage technologies Key Concepts Conclusions
Applications from utilities based to behind the meter
Review of available technologies
Key Concepts
Power vs. Energy
Discharge time
Challenges
Conclusions

5. Superconducting Magnetic
Energy Storage Methods
Energy Storage
Mechanical
Chemical
Electromagnetic
Thermal
Pumped Hydro
Flywheel
Batteries
Hydrogen
Sensible
Heat
Latent
Heat
Superconducting Magnetic
Flow Batteries
Solid State
Capacitors
Thermochemical
Compressed Air (CAES)
Brahim Dincer, Marc Rosen, (2011) “Thermal Energy Storage, Systems and Applications” Second Editions

6. Energy Storage Technologies
Mechanical Systems
Pump-Hydro
Compressed air energy storage (CAES)
Flywheels
Non-Mechanical Systems
Batteries
Super Capacitors
Superconducting Magnetic Energy Storage

7. Pump-Hydro
Works based on hydro-power plant concept

8. Compressed Air Energy Storage
Based on combination of gas turbine technology and Brayton Cycle

9. Flywheel
Based on Newton’s first law

10. Batteries
Several types of batteries are available for different storage applications
High power
High energy density

11. Other Technologies Super Capacitors
Super-conducting Magnetic Energy Storage (SMES)
High power
Very short discharge time

12. Energy Storage Space

13. We store Energy not Power
Power vs. Energy
Energy
Energy is a property of objects which can be transferred to other objects or converted into different forms, but cannot be created or destroyed.
Unit: kWh, Jouls
Energy per unit time is Power.
Power
The ability to work
Unit: kW, MW
Large power is needed for for large applications.
Utility scale storage provides high power, while residential scale requires lower power.
We store Energy not Power

14. Discharge time Time of dispatching the energy at a given power.
Different applications requires different discharge time.
Residential ratchet charge requires short discharge times.
Frequency regulating requires very rapid discharge times.
For most of renewable energy, longer discharge times are desired.
Batteries are not capable of longer discharge time yet.
Pump-hydro and CAES can provide longer times.

15. Key Challenges

16. “Important” Parameters
Efficiency
$/kW.hr
$/kW
LCOE

17. Efficiency of Energy Storage System
“Round trip” Efficiency
Different than “thermodynamic efficiency”
How important is efficiency?
Depends on whom you asked!

18. Cost of Energy Stored
$/kW.hr

19. Cost of Power Produced $/kW Is this a correct formula?
Does this make sense for energy storage?

20. Levelized Cost of Energy
LCOE
LCOE is equivalent to the cost of energy stored.
If LCOE is larger than cost of Energy purchased, energy storage business fails.
Government incentives are important.
But is that all? LCOE doesn’t tell you everything you need to know!

21. Conclusions
Both power and discharge time are very important for an energy storage system.
Batteries are capable of very short to intermediate discharge times
Very suitable for demand peak shaving and frequency regulations.
Pump-hydro and CAES are suitable for high power, long discharge time.
Relatively longer ramp time, limits these systems to longer respond time applications.
Efficiency is important only if it is worth it.
Cost, Cost, Cost!!!

22. THANK YOU
FOR ATTENDING THE PRESENTATION