September 9, 2003

1
Overview of Wind-H2 Configuration Control Model
(WindSTORM)
September 9, 2003 Lee Jay Fingersh National
Renewable Energy Laboratory
2
Introduction

• Wind is intermittent
• Hydrogen production, storage and fuel cells can
  be used to store electricity
• Batteries can also store electricity
• Hydrogen can also be produced from wind to be
  used as a fuel
• What is the best approach to combine hydrogen
  systems with wind?

3
Wind-hydrogen interface optimization
4
Classical wind-hydrogen storage system
Power Grid
Storage system efficiency 25 to 35
e-
Variable-speed drive
e-
Wind turbine
e-
Rectifier
e-
Inverter
e-
e-
e-
Electrolyzer
Fuel-cell
H2
H2
H2
Fuel
H2
Storage
Compressor
5
Storage system with shared power converter
Power Grid
Storage system efficiency 30 to 40
e-
Variable-speed drive
e-
Wind turbine
e-
e-
e-
e-
e-
Electrolyzer
Fuel-cell
H2
H2
H2
Fuel
H2
Storage
Compressor
6
H2 only system
Storage system efficiency 30 to 40
e-
e-
e-
e-
e-
e-
e-
H2
H2
H2
Fuel
H2
7
Battery and H2 system
Power Grid
Storage system efficiency 80 to 85
e-
Variable-speed drive
e-
Wind turbine
e-
e-
e-
In-tower low-pressure Storage
e-
e-
e-
H2
Electrolyzer
Nickel-hydrogen battery
Fuel-cell
H2
H2
Fuel
H2
8
Battery only system
Power Grid
Storage system efficiency 85 to 90
e-
Variable-speed drive
e-
Wind turbine
In-tower low-pressure Storage
e-
e-
e-
H2
Nickel-hydrogen battery
9
Battery technology discussion

• Batteries for grid interconnect will be subjected
  to an enormous number of cycles in a 20 year
  lifetime
• One of the only battery chemistries that can
  withstand repeated daily cycles for 20 years is
  Nickel-Hydrogen
• Used in space applications for the same reason
• Uses the same reaction as nickel-metal-hydride
• Uses separate hydrogen storage rather than
  storing hydrogen in the electrode
• Cycle life reported to be 10,000 to 500,000
  cycles
• 2 cycles per day for 20 years is 15,000 cycles

10
Analysis Approach (WindSTORM)

• Analysis is needed to answer What is the best
  approach to combine hydrogen systems with wind?
• Simulate calendar year 2002
• California ISO load data
• Windfarm data from Lake Benton, MN
• Requirement Power must balance hourly
• Seek to reduce necessary traditional generation
  capacity (windpower capacity credit)
• Determine optimal control methodology
• Calculate system size and cost

11
Analysis parameter assumptions

• Wind has 50 capacity credit
• 100 MW wind farm reduces peak requirements on
  traditional generation by 50 MW
• Equivalent to 50 MW firm power from 100 MW
  windfarm
• Wind has 12 energy penetration
• Wind has 20 capacity penetration
• No net hydrogen production
• Battery charge efficiency 95
• Battery discharge efficiency 90
• Electrolyzer efficiency 75
• Fuel cell efficiency 50

12
Cost assumptions

• Cost of Wind 1,000/kW
• Cost of battery 70/kWh
• Cost of electrolyzer 600/kW (2010)
• Cost of fuel cell 600/kW (2010)
• Cost of H2 storage (in-tower) 3/kWh (100/kg)
• FCR 11.58
• OM fixed at 0.008/kWh

13
Example of system performance
14
Effect of forecasting
15
Battery and H2 and H2 only systems
16
Important notes

• The battery hours of storage required and cost of
  energy can vary dramatically with changes in the
  system
• Windfarm location
• Windfarm size
• Control methodology
• Forecasting method

17
Alternate approach produce hydrogen

• Utilize slightly larger electrolyzer and more
  aggressive control strategy to produce some net
  hydrogen
• All other requirements remain in effect
• Electricity price 0.04/kWh
• Hydrogen price 0.10/kWh
• Capacity credit 18/kW/year

18
System designed for hydrogen production
19
Analysis of hydrogen production scenarios

• Battery and H2 system with hydrogen production
• 5 of windfarm output turned into hydrogen
• Enough to support about 2,250 vehicles
• 10.7 of windfarm revenue from hydrogen
• 5.8 of windfarm revenue from capacity credit
• Cost of H2 production 0.072/kWh (2.40/kg)
• Cost of H2 production is low because electrolyzer
  capacity factor is greater than 58.
• Cost drops to 0.062/kWh (2.06/kg) if
  electrolyzer cost drops to 300/kW
• H2 only system no electricity
• Cost of H2 production 0.081/kWh (2.70/kg)
• Cost of H2 production is higher because of lower
  electrolyzer capacity factor (38)

20
Conclusions

• It is possible to firm up wind power for a
  roughly 10 increase in COE.
• Using batteries is cost effective
• Using hydrogen systems alone is not cost
  effective because the closed-cycle efficiency is
  too low
• Hydrogen production can be simultaneously
  accomplished and is cost effective
• Hydrogen production alone Is less cost effective
• Control strategy and proper system sizing are
  very important
• With further investigation, it may be possible to
  do much better