Post on 14-Jan-2016
transcript
Supercapacitors for EV and Grid-Scale Energy Storage
Silverberg8 Oct 2015
Outline
• Context– Why do we need energy storage?– What is a supercapacitor?– What can supercapacitors do for us?
• Research: Graphene supercapacitors• Industry: Sunvault, Maxwell, Volvo
Functions for Energy Storage
• Portable electronics (5-100 Wh, <50 cm3)• Transport (50 – 100 kWh, 500 kg) main, regenerative, start/stop
• Grid-scale (MWh, cost) meeting peak load, smoothing renewable
Grid-Scale Energy Storage
DoE, 2013
Key Metrics for Comparison
*Cycle life
Electric Vehicle Energy Storage
Li-ion battery
Zhang et al. 2015
Key Metrics for Comparison
*Energy density
Capacitor
C = = E = ½ CV2
• Energy density: 0.01 Wh/kg• Power density: 10 kW/kg• 500,000 cycles
Supercapacitor
• Energy density increase to ~5-10 Wh/kg
Battery vs. Capacitors
Li-ion Battery Capacitor Supercapacitor
Charge Time 600 s 0.001 s 10 s
Cycle Life 1000 500,000 500,000
Specific Energy 150 Wh/kg 0.01 Wh/kg 5 Wh/kg
Specific Power 1 kW/kg 10 kW/kg 10 kW/kg
Energy Cost $1/Wh $5000/Wh $20/Wh
Solar Power Smoothing
Solar Power Smoothing
UCSD microgrid provides 90% of campus power
22 kW CPV with 2.5 kWh supercap
Scale of problem is TBD
0 100 200 300 400 500 600 700 800 900 1000010203040506070
Time (s)
Velo
city
(km
/h)
Regenerative Braking
ARTEMIS by INRETS
Regenerative Braking
Regenerative Braking
Philadelphia SEPTA subway
10-30% reduction in grid-use
Also acts as grid storage
Future Application: EV/Small Grid-Scale Storage
Li-ion Battery Capacitor Supercapacitor
Charge Time 600 s 0.001 s 10 s
Cycle Life 1000 500,000 500,000
Specific Energy 150 Wh/kg 0.01 Wh/kg 5 Wh/kg
Specific Power 1 kW/kg 10 kW/kg 10 kW/kg
Energy Cost $1/Wh $5000/Wh $20/Wh
Graphene
Specific Capacitance Specific Energy
Theoretical single layer graphene: over 100 Wh/kg
Zhang et al. 2015
Graphene, theory
Graphene, expt
Energy Density is the key
Graphene supercapacitors
2007200820092010201120122013201420150
100
200
300
400
500
600
GSCsTypical SupercapacitorGraphene Theoretical
Year
Spec
ific
Capa
citr
ance
(F/g
) >100 Wh/kg
Graphene supercapacitors @ UCLA
http://www.sunvaultenergy.com/web20/video-updates/
SunVault
• “The company has had 4 different names since 2010 and 2 different business lines.• There is little technical detail in the company's press releases and website to support
its claims.• The majority of the company's stock is held by third parties with little information
available on them.” – Seeking Alpha
“A company no one has ever heard of is using technology no one has ever heard of to make a car with 1,000 lb-ft of torque that will blow the doors off any Tesla, Ferrari or McLaren every made. And it will be ready in 6 months.” –Ecomento
“Sunvault Energy Inc (OTCMKTS:SVLT) Stock Surges For No Apparent Reason” - HotStocked
Volvo Energy Panels, 2013
Maxwell & GM Partnership, Sep 2015
Start-stop technology
Outlook
• Continued use for high power, low energy applications– Regen braking– Start/stop– High-frequency smoothing
• With further energy density improvements– EV power– Larger grid-scale applications
Supp: Parameters for Supercap Optimization