Bob HebnerDirector , Center for
ElectromechanicsUniversity of Texas at Austin
100+ researchers into energy storage, smart grid, and energy technology
Working for seven years on “Smart Grid” for DoD
Storage programs in flywheels, batteries, ultracaps, compressed air, and thermal
Reconfiguration approach handles:
• Fuel minimization
• Power system protection• Damage mitigation
Reconfiguration via optimization
Using a power objective function
Subject to:
Attributes• Permit active participation by consumers • Accommodate generation and storage
options • Enable new products, services, and markets • Provide power quality • Operate efficiently • Reconfigure in response to system
disturbances Technology
• Traditional power engineering• Computing• Telecommunications
Top down• Large scale wind farms• Smart meters
Bottom up• Microgrids
Neighborhoods Industry Universities DoD facilities Urban environments
Sources connected to loads through a grid• Pearl Street
Operate at 60Hz• Texas storage
Today’s grid• Capacity constrained• Loads demand clean power• Cascading failure
Charge-discharge rate Turnaround efficiency Storage losses Lifecycle cost Size/weight
• High rates and depths of discharges,- Flywheels have best properties.
• Long storage times and low rates and depths of discharge
- Batteries usually are best• Between the extremes,
-There are many competitive solutions
Storage OptionSelf Discharge time (1)
Round trip efficiency
Flywheel 2-12 hours 0.9
Ultracapacitor 3% per day = 1 month 0.8
Battery 3% per day = 1 month (NiCd) 0.7
Power quality• Sensitive loads• Increase use of renewables
Diurnal shifting• Broader use of renewables• Greater return on investment
Frequency stabilization• Improved system reliability• Increase use of renewables
Plug-in hybrids Increase effective grid capacity Provide reconfiguration support
Flywheel – 1 MW, 3 minutes
Key technology advances for storage include:• Rapid charge/discharge batteries with long
life• Lower loss magnetic bearings• Stronger composites to reduce windage loss• Innovative control strategies• Advanced scaling approaches
Transmission companies Generating companies Distribution companies Regulators Storage manufacturers Microgrid developers
Different needs for storage, different definitions of success
Focus on metering• Positive: Opens opportunity for innovative
local storage• Negative: May give “Smart Grid” a bad
name Storage Stimulus
• Positive: Lowers the first cost barrier for innovative storage technology
• Negative: Wrong technology/application choices may poison the well
Storage critical for “Smart Grid”• Most agree, but assume different
applications Excellent storage choices exist today With R&D, better choices will exist in
the future Evolution of “Smart Grid” is a work in
progress• Storage can help shape the evolution