Prudent Energy

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Prudent Energy Storage for a sustainable
futureThe Global Leader in Advanced Energy
Storage Large scale Energy storage
applications of the VRB-ESS in providing
electrical grid power solutions
Timothy Hennessy June 15 2012
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About Prudent Energy

• 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

Company Overview
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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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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

V5 -gt V2
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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
• lt 1 cycle responses
• Low pressure and low temperaturesafe
• Disadvantages
• Low energy storage density big footprint
• Not mobile

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The modular assembly of a MW scale VRB-ESS in
California
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The modular assembly of a MW scale VRB-ESS in
California

• Peak Shaving
• Using bio gas from onion plant
• Gills Onions California

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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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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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KW class VRB-ESS for Telecoms and commercial
sites

• 5 to 10kW
• No refuelling costs
• Long Life (10 years)- electrolyte never wears
  out
• No degradation on deep cycling
• Low maintenance
• Always on no bridging power needed - SOC
  always known
• Long duration storage independent of power
  scalable up to 10 hours
• Closed loop no emissions no disposal issues

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VRB characteristics from field testing
Response time ms

1. Response time full charge to discharge lt 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

Short circuit test
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Cell stack evolution - 2002 2012
SEI 42kW stack
VRB P3 5kW- 10kW
VRB P3 2010
VRB P1 5kW 2004
S5 stack 2012
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Schematic of a conventional battery and PCS are
separate
VRB-ESS is a system
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PCS Power Conversion system

• Sized in modular form ABB PCS-100 provides 4
  quadrant operation, PQ and FS modes of
  operation ABB PCS 100

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HMI Power Screen for the VRB-ESS
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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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4MW 16MWh Plant
33m x 35m for delivery 2013
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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
• 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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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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Comparisons of Wind and PV systems with energy
storage for municipal owned microgrids

• 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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Firmness provided by storage in islanded micro
grids
Grid purchases when storage sized at 1hour
Wind (MW) Wind (MW) 5
PV (MW) PV (MW) 4
1 hour storage duration Grid purchase (times/year) 230
1 hour storage duration Energy purchases (MWh) 604.7
4 hours storage duration Grid purchase (times/year) 152
4 hours storage duration Energy purchases (MWh) 35.8
6 hours storage duration Grid purchase (times/year) 8
6 hours storage duration Energy purchases (MWh) 2.7
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Peaking generation enhancing the value of OCGT
using Energy Storage
Also reduces CO2 emissions
Ref PJM USA markets
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Energy trading using flow batteries in Germany
IRR over ten years gt 15
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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

Pumped Storage Compressed Air Energy Storage (CAES) Hydrogen Open Cycle Gas Turbines, Diesels or Coal Fire Station Electrochemical Energy Storage
Solutions
Comments Mature Long lead time Geographical limitation Large scale Lowest cost Limited by geology Central type plant Long lead time Large scale Long duration Expensive with low efficiency Risky Highest energy density Central type plant Medium CAPEX High impact on environment Low average efficiency Risky gas supply Fast delivery Low operating cost Environmentally friendly Higher initial CAPEX
Fit for Commercial Grid Storage Applications Exists part of mix not distributed Possible part of mix Possible part solution Yes part of mix Distributed essential part of solution
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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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