Electricity storage technologies like flow batteries and sodium sulfur batteries can store excess energy from windfarms and industrial sites. While these technologies are not yet economically viable for widespread windfarm or industrial use, their economics may improve with mass production and reduced costs. A research project at Dundalk Institute of Technology is installing a flow battery to develop optimal control algorithms and gain practical experience with the technology to help advance its economic viability over time.

1. Electricity Storage
Windfarm and Industrial Applications
L. Staudt, Centre for Renewable Energy
Dundalk Institute of Technology

2. Presentation Summary
 Technology overview
 Windfarm application
 Industrial application
 Conclusions

3. Technology Overview

4. Technology Overview

5. Technology Overview

6. Technology Overview

7. Technology Overview
Economics
 Profit per transaction (P)
 value of sales must exceed value of purchases
 Number of transactions per year (n)
 As many as possible!
 Good business: when product of both is
maximized (P x n = max)

8. Technology Overview

9. Technology Overview

10. Technology Overview
Why flow and NaS batteries (for windfarm
and industrial applications)?
 Flow batteries (and NaS) provide high power and
high energy
 You can easily and independently select both
power and energy, as the products are modular
 They have no special site requirements
 Will first discuss flow batteries, then NaS

11. Technology Overview
 A flow battery is an electrochemical electricity
storage device, somewhere between a
standard rechargeable battery and a fuel cell
 The energy is stored (only) in the electrolytes,
which can be fully discharged and recharged
 Power and energy are independent
 More power: add flow cells
 More energy: add electrolyte

12. Technology Overview
Basic flow battery
schematic

13. Technology Overview

14. Technology Overview
Moab, Utah
250kW 8 hour installation

15. Technology Overview
Moab, Utah

16. Technology Overview
Tomamae windfarm, Japan
4MW, 1.5 hour flow battery
installation

17. Technology Overview
RISO 15kW, 8-hour
flow battery

18. Technology Overview
Advantages of flow
battery technology
 Flexible location  Operate at ambient
 Good energy density temperatures
 Independent energy and  Acceptable cycle
power sizing efficiency
 Thousands of deep  Mass market should lead
charge/discharge cycles to lower costs
(long lifetime)  Quiet operation

19. Technology Overview
Flow battery concerns
 Cost  Current density can be
 Proven reliability improved
 Proven efficiency  Environmental issues
(appears OK)
 Technology not mature –
may have “surprises”  Needs a building
 Maintaining electrolyte  Business stability (early
purity (appears OK) days)

20. Technology Overview
NGK Sodium Sulphur battery
(not a flow battery)

21. Technology Overview
NGK NaS battery

22. Technology Overview (NaS)
 NaS vs. flow battery
 Longer commercial history
 Cycle life depends on DOD
 Better energy density
 No building required
 Higher efficiency
 Lower cost?

23. Technology Overview
Vanadium Zinc Bromine Cerium Zinc NaS (NGK)
Redox (VRB) (ZBB) (Plurion)
Efficiency 65-75% 60-70% 70-80% 75-85%
Lifetime >10,000 cycles >1500 cycles >15,000 cycles ~5000 cycles
Cost (w/o building) (w/o building) (w/o building)
4-hour system €1800/kW €1800/kW €1800/kW €1400/kW
8-hour system €2600/kW €2600/kW €2600/kW €2400/kW
O&M cost 0.5% of Capex 0.5% of Capex 0.5% of Capex 0.25% of Capex
Wind projects Kings Island n/a n/a Hachijo Island
200kW/800kWh 400kW/3MWh,
Tomamae many non-wind
4MW/6MWh

24. Presentation Summary
 Technology overview
 Windfarm application
 Industrial application
 Conclusions

25. Windfarm application
 We created a model that optimally dispatched
storage at a 12MW windfarm in the UK (using
real UK market prices and windfarm output)
 Our model determined maximum revenue over
the course of a year (purchase cost less sales
cost for each half hour)
 Usually resulted in full charge/discharge each
day, but may not e.g. if efficiency is low and
price spread is low

26. Windfarm application
 A number of cases run for different sizes (MW
and MWh) and different efficiencies
 Base case: 5MW/20MWh with 75% efficiency
 Gives an optimistic result, due to optimal
operation Selectable battery cost: €X per MW
plus €Y per MWh (base case of €1m per MW
and €200k per MWh)
 Adjustable O&M cost (base case of 0.5% of
Capex)

27. Windfarm application
Effect of battery energy rating for a 5MW battery
system on a 12 MW windfarm

28. Windfarm application
Effect of battery power rating for a 20MWh battery
system on a 12 MW windfarm

29. Windfarm application
 Base case efficiency and prices achieve a minimum
payback period of 35 years
 Efficiency is very important – 60% to 80% efficiency
gives a 31 to 54 year payback
 Halving battery costs gives minimum payback of 17
years for base case
 Further benefit possible by considering balancing
penalties and ancillary services value

30. Windfarm application
 Conclusions (windfarm application)
 Battery costs must decrease substantially
 Factors that will improve economics:
 Mass production
 Improved efficiency
 Electricity market price spread
 Value given to ancillary services
 Technological breakthroughs

31. Presentation Summary
 Technology and Application overview
 Windfarm application
 Industrial application
 Conclusions

32. Dundalk IT storage project
 In 2005 we installed a large scale commercial
wind turbine on the Dundalk IT campus
 It operates as an autoproducer which results in
the reduction in electricity bills
 Excess electricity generated is exported to grid
 Electricity deficit is imported from grid
 Now Dundalk IT is installing a flow battery for
primarily research purposes but will also further
reduce annual electricity bills

33. The Campus Wind Turbine at Dundalk
Institute of Technology

34. Dundalk IT storage project
Grid (10kV 3 phase) Wind Turbine
690V 3Phase
Circuit 10kV 3Phase
Breakers Transformer in base of turbine
& Metering 690V/10kV
SCADA PC
On site transformer
10kV/400V
To other DkIT
transformers
400V 3 phase PCS/Battery
(10kV/400V)
To DkIT Loads

35. Dundalk IT storage project
Incomer Meter
(Grid)
Wind Turbine
Meter
DkIT HV switchroom

36. Dundalk IT storage project
Monthly Data
450000
400000
350000
300000
250000
kWh
200000 DkIT consumption with no WTG
150000
WTG P roduction
100000
50000
0
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ay
ly
ec
ne
p
ar
ov
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Ja
Fe
Se
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A
M
M
A
D
Ju
N
Month
Monthly DkIT energy
production and consumption

37. Dundalk IT storage project
Monthly Electricty Demand vs Wind Turbine Production (No Storage)
450000
400000
350000
300000
250000
kWh DkIT consumption with no WTG
200000 Total WTG Production
150000 DkIT consumption with WTG
WTG Exported Energy
100000
50000
0
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ct
ay
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ar
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Ap
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No
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Month

38. Dundalk IT storage project
 Following a successful application to Enterprise Ireland
for a Capital Equipment grant, Dundalk IT tendered for a
125kW, 500kWh flow battery – September 2008
 Tender awarded to ZBB (USA) – end of 2008
 Battery system manufactured and tested – February to
May 2009
 Battery acceptance testing – June 2009
 Shipped to Dundalk IT – August 2009
 Installation preparation underway at DkIT

39. Dundalk IT storage project

40. Dundalk IT storage project
Sea box container
DC
50kWh 50kWh 50kWh 50kWh 50kWh
AC
PCS
50kWh 50kWh 50kWh 50kWh 50kWh
Chiller Unit

41. Dundalk IT storage project
Cell
stacks

42. Dundalk IT storage project
Power conditioning
system during FAT

43. Dundalk IT storage project
Control
system
display

44. Dundalk IT storage project
Battery
foundation

45. Dundalk IT storage project
Battery
foundation

46. Dundalk IT storage project
 Economics depend on a number of factors
including:
 Electricity tariffs
 Battery capital costs
 Battery efficiency
 Value given to potential utilization of waste heat

47. Dundalk IT storage project
 A model was developed by DkIT to evaluate the
addition of electricity to the wind turbine
 It takes half hourly power production and
consumption data and MIC for a year and then
calculates the annual savings for a given battery
rating (kW), capacity (kWh) and efficiency using
given electricity tariffs
 Option to give value to waste heat is included

48. Dundalk IT storage project

49. Dundalk IT storage project
 Various model outcomes
 Battery capital cost €575,000
 Battery efficiency 65%
Some Scenarios Value given to Value given Total DkIT Annual savings due
exports to waste heat Annual Costs to battery
(€/kWh) (€/kWh) (€) (€)
No storage NA N/A 330,025 N/A
125kW, 500kWh 0.00 0.00 322,156 7,488
125kW, 500kWh 0.057 0.00 290,620 3,597
125kW, 500kWh 0.00 0.04 318,622 11,022
125kW, 500kWh 0.057 0.04 287,086 7,131

50. Dundalk IT storage project
 As wind autoproducers operate differently to
conventional power generators no value is available at
present for:
 Operating Reserve
 Reactive Power Generation
 Black Start
 Capacity

51. Dundalk IT storage project
 Conclusions (industrial application)
 Battery storage in commercial industrial wind
autoproduction applications difficult to justify
economically at present
 Significant reduction in system costs in mass
production coupled with increasing electricity
prices should make these systems viable with wind
autoproduction in the medium term

52. Dundalk IT storage project
 However, it is a research project..
 The flow battery facility at DkIT will allow:
 Development and test of control
(charge/discharge) algorithms so that the
operation of system will maximise economic return
 This will incorporate a number of factors including,
electricity prices, wind and load forecasting
 Practical experience and assessment of actual
performance of this technology

53. Presentation Summary
 Technology and Application overview
 Windfarm application
 Industrial application
 Conclusions

54. Overall conclusions
 Electricity storage has a bright future
 Storage will be ubiquitous in electricity grids,
becoming “The Fourth Element”
 There are presently a number of immature but
promising storage technology
 The technology is not yet generally economic in
windfarm and industrial applications
 Economics will improve with mass production,
and with value being given to ancillary services

55. Questions?
larry.staudt@dkit.ie
www.credit.ie