Large scale Energy storage. Applications of the VRB-ESS® in providing electrical grid power solutions

1. Prudent Energy
Storage for a sustainable future
The Global Leader in Advanced Energy Storage
Large scale Energy storage – applications of the VRB-ESS®
in providing electrical grid power solutions
Intersolar 2012
Timothy Hennessy June 11 2012

2. About Prudent Energy
Company Overview
• Provides proprietary VRB® Energy Storage Systems (VRB-ESS®) for grid and
renewable energy storage applications between 200kW to 10MW 100MWh
• 10 years operation with the VRB® technology: 200 employees
• Over 20MWh commercial sales and installations in last year across 11 countries
• VRB® and storage application Patents: control all substantial patents including
51 issued patents and 48 pending patent applications in 34 countries
• Major Investors: MITSUI Corporation, GS Caltex, State Power Group, DFJ and
DT Capital, CEL, Northern Light
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3. Prudent VRB® Technology
What is a Flow Battery?
 Regenerative fuel cell or “Cell
Stack”
 Independent electrolyte storage
tanks
 Pumps to circulate electrolyte
 Control system to manage
electrolyte circulation
 Flow battery technologies are
distinguished by electrolyte
composition
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4. Prudent VRB® Technology
Flow Battery Cell Stack
 Array or “stack” of individual
cells in series
 Each cell consists of
 bipolar plate
 2 electrodes
 Membrane separator
• Colors of Vanadium at different ionic states
• Non Toxic
• Readily available from waste streams such as flyash
V+5 -> V+2
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5. Prudent VRB Technology
Flow Battery Advantages and Disadvantages
Advantages
 No daily “off periods” - always on
 Power and energy capacity can be sized
independently of one another
 Operates at any SOC without life impact
 Any Depth of Discharge (DOD)
 Lowest LCOE (unlimited cycles of
electrolyte)
 Large surge capability possible
 Efficient over 100% DOD range
 < 1 cycle responses
 Low pressure and low temperature=safe
Disadvantages
 Low energy storage density = big footprint
 Not mobile
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6. The modular assembly of a MW scale VRB-ESS® in California
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7. The modular assembly of a MW scale VRB-ESS® in California
• Peak Shaving
• Using bio gas from
onion plant
• Gills Onion’s
California
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8. MW scale VRB-ESS® in China - wind and PV smoothing
 500kW 750kW pulse (10 minutes) / 1MWh
 Results – one of other technologies has
had performance issues within a year
 Our performance has been solid
 Ambient temperatures down to -30C
 Provides continuous reactive energy
(MVAR)
 2MW * 8MWH system being
commissioned in September 2012 – wind
PV - grid connected
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9. Microgrids – island and hybrid systems
• 400kW x 500kWh diesel, PV
and micro-hydro, Hybrid in
Indonesia
• Slovakia – smart grid 600kWh
• Hawaii – islanded PV
• China – smart grid wind and PV
• Korea Smart grid Jeju island
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10. VRB® characteristics from field testing
Response time ms
Short circuit test 1. Response time full charge
to discharge < 50ms
2. Stack Coulombic efficiency
3. Short circuit test – stack
shorted max 2000 Amps.
Discharged over 140
seconds. System recovered
after short removed
4. Longest field operation 6
years un-manned
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11. Future enhancements to VRB® Technology
• Energy density of electrolyte being improved – reduces footprint and costs
• Footprint reduction of plant – higher efficiency of cell stacks
• Market driven cost reductions depends on application e.g. renewable power
smoothing, peak shaving etc.
• Modular 250kW
• 40% footprint reduction
2011 to 2013
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12. Implications of community based generation in Distribution System
• Power flows no longer in
one direction due to multiple
sources
• Complex protection
coordination due to multiple
generation sources storage
• Microgrid or community
grids contains both
generation and load
• Managed independently
of main distribution
system and can operate
even if main transmission
source is cut
Courtesy Brad Williams Oracle
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13. Germany Current Situation
Reports on critical grid conditions [Reference: Paul-Fredrik Bach: Frequent wind
power curtailments 14 April 2012]
Recently “Welt Online” reported on “alarm level yellow” for German power grids on 28
and 29 March 20121..
During first quarter EON Netz has issued 257 interventions.. Thus there have been
interventions active for 23.1% of the hours in first quarter.
Part of the solution is storage backed
microgrids owned by communities
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14. Comparisons of Wind and PV systems with energy storage for municipal
owned microgrids
Net Power with 9MW PV and No Wind Net Power with 9MW Wind and No PV
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4 Hours Storage Duration 4 Hours Storage Duration
6 Hours Storage Duration 10 6 Hours Storage Duration
8
8
6
6
Power, MW
Power, MW
4
4
2
2
0
0
-2 -2
0 100 200 300 400 500 600 700 800 0 100 200 300 400 500 600 700 800
Time, Days Time, Days
4 cases: Objective to minimize grid demand and reduce volatility of power sold to grid.
• PCC= 9MW: Below zero in graphs indicates grid purchases i.e. NON FIRM
renewable resource
• Smoothing effects and ramp rate (stability) management provided by energy storage
• Cases examine mixes of PV and wind generation along with 2.5MW of storage with
durations of 1, 2, 4 and 6 hours all at 2.5MW FIRM PPA with utility
• Finding is that between 4 to 6 hours of storage yields lowest volatility and minimum
grid purchases.
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15. Firmness provided by storage in islanded micro grids
Net Power with 5MW Wind and 4MW PV Net Power with 5MW Wind and 4MW PV
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1 Hour Storage Duration 4 Hours Storage Duration
6 Hours Storage Duration 6 Hours Storage Duration
10 10
8 8
6 6
Power, MW
Power, MW
4 4
2 2
0 0
-2 -2
0 100 200 300 400 500 600 700 800 0 100 200 300 400 500 600 700 800
Time, Days Time, Days
Grid purchases when Wind (MW) 5
storage sized at 1hour 4
PV (MW)
1 hour storage duration Grid purchase (times/year) 230
Energy purchases (MWh) 604.7
4 hours storage duration Grid purchase (times/year) 152
Energy purchases (MWh) 35.8
6 hours storage duration Grid purchase (times/year) 8
Energy purchases (MWh) 2.7
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16. Peaking generation enhancing the value of OCGT using Energy Storage
Also reduces CO2 emissions
Ref: PJM USA markets
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17. Energy trading using flow batteries in Germany
IRR over ten
years > 15%
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18. Summary of Alternative Grid Energy Storage Solutions
Electrochemical energy storage is the most preferred practical solution for distributed
grid energy storage applications but one size does NOT fit all
Compressed Air Open Cycle Gas
Energy Storage Electrochemical
Pumped Storage Hydrogen Turbines, Diesels or
Energy Storage
(CAES) Coal Fire Station
Solutions
• Mature • Limited by • Long duration • Medium CAPEX • Fast delivery
• Long lead time geology • Expensive with • High impact on • Low operating
• Geographical • Central type low efficiency environment cost
limitation plant • Risky • Low average • Environmentally
Comments
• Large scale • Long lead time • Highest energy efficiency friendly
• Lowest cost • Large scale density • Risky gas • Higher initial
• Central type supply CAPEX
plant
Fit for
Commercial Distributed
Grid Storage essential part of
Applications Exists – part of Possible part of Possible part Yes part of mix
mix not distributed mix solution solution
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19. Summary and observations
 Energy Storage can be used to “FIRM” variable generation resources
both centrally and distributed
 Electrochemical Storage prices are coming down
 GAS fired generation combined with storage for fast acting reserve is
more economic than standalone gas fired generation alone.
 Distributed Storage must form part of any SMART GRID in order to
manage power flows
 An approach to microgrids allowing communities to island their resources
will occur and regulations applying to these should be developed
 Long term storage is essential for stability and energy management
in distributed generation grids
 Government and regulatory bodies must lead the way in setting
appropriate policy and tariffs such as locational marginal pricing to direct
storage investments
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