September 9, 2003Lee Jay Fingersh

National Renewable Energy Laboratory

Overview of Wind-H2 Configuration & Control Model (WindSTORM)

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?

Wind-hydrogen interface optimization

Generator Interface

DC Bus Grid Interface

Electrolyzer Fuel Cell or Combustion

Device

Battery

Multi-Pole Switch or Switches

Wind turbine power converter

Classical wind-hydrogen storage system

Power GridVariable-speed drive

Rectifier

Electrolyzer

Compressor Storage

Fuel-cell

Inverter

Wind turbine

Storage system efficiency: 25% to 35%

Fuel

e-

e-

e-

e-

e-

e-

H2H2

H2

e-

H2

Storage system with shared power converter

Power GridVariable-speed drive

Electrolyzer

Compressor Storage

Fuel-cell

Wind turbine

Storage system efficiency: 30% to 40%

Fuel

e-

e-

e-

e-

e-

e-

H2H2

H2

e-

H2

“H2 only” system

Power GridVariable-speed drive

Electrolyzer

In-tower low-

pressure Storage

Fuel-cell

Wind turbine

Storage system efficiency: 30% to 40%

Fuel

e-

e-

e-

e-

e-

e-

H2

H2

H2

e-

H2

“Battery and H2” system

Power GridVariable-speed drive

Electrolyzer

In-tower low-

pressure Storage

Fuel-cell

Wind turbine

Nickel-hydrogen battery

Storage system efficiency: 80% to 85%

Fuel

e-

e-

e-

e-

e-

e-

H2

H2

H2

e-

e-

H2

“Battery only” system

Power GridVariable-speed drive

In-tower low-

pressure Storage

Wind turbine

Nickel-hydrogen battery

Storage system efficiency: 85% to 90%

e-

e-

e-

e-

e-

H2

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

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

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%

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% O&M: fixed at $0.008/kWh

Example of system performance

"Battery and H2" system load balanace

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 16 18 20 22

Hour of day

Po

we

r (k

W)

(No

n-h

yd

rog

en

sy

ste

ms

)

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

Po

wer (kW

) (Hyd

rog

en system

s)

BatteryTraditional generationWind powerEnergy storedLoadElectrolyzerFuel Cell

Effect of forecasting

"Battery only" storage system

0.03

0.04

0.05

0.06

Battery only system With CAISO load forecasting With perfect wind forecasting andCAISO load forecasting

CO

E (

$/kW

h)

0

0.5

1

1.5

2

2.5

3

3.5

Battery S

ize (ho

urs)

COE (system) COE (wind only) Battery size

“Battery and H2” and “H2 only” systems

Systems with H2 storage included

0.04

0.05

0.06

0.07

0.08

0.09

Battery and H2 system H2 only system

CO

E (

$/kW

h)

0

0.5

1

1.5

2

2.5

Battery S

ize (ho

urs)

COE (system) COE (wind only) Battery size

Same battery size and COE as "Battery Only" system with forecasting because

optimizer optimized H2

system to zero size

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

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

System designed for hydrogen production

Costs and revenue with and without hydrogen production

0

5

10

15

20

25

30

Battery and H2 system Nohydrogen production

Battery and H2 system withhydrogen production

H2 only system with hydrogenproduction only - no electricity

Rev

enu

e (M

$/ye

ar)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

CO

E ($/kW

h)

Electricity Hydrogen Capacity COE

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%)

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