a probabilistic method for sizing of isolated wind-electrolyser systems

A Probabilistic Method for Sizing of Isolated Wind-Electrolyser Systems

Lars Nesje GrimsmoNTNU

Magnus KorpåsNTNU

Terje GjengedalNTNU/Statkraft

Steffen Møller-HolstSINTEF Materialteknologi


Plant overview


~=

== =

~

hydrogenstorage

electrolysisplant

battery

dumpload

hydrogenoutput

oxygen

windmill

feedwater

auxiliaryloads

Principles of water electrolysis


PEM Electrolysis

H2

e-

O2H+

membranecathode anode

H2O

cathode: 2H+ + 2e- H2

andoe: H2O 2H+ + 2e- + ½O2

H2

Alkaline Electrolysis

cathode: 2 H2O + 2e- H2 + 2OH-

anode: 2OH- ½O2 + H2O + 2e-

electricity + H2O H2 + ½O2

e-

H2O

KOH

O2H2

Electrolyser performance


0 1000 2000 3000 40001.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

Current density [mA/cm2]]

Ce

ll vo

ltag

e [V

]

Alkaline (GHW/Hydro)

PEM (NTNU)

PEM (Expected performance)

Benefits of wind-electrolyser systems


• Exploitation of wind resources in areas with no electricity infrastructure.

• Hydrogen from renewables is an environment-friendly fuel.

• Hydrogen could be used both for transportation and for stationary energy supply.

• Oxygen as a by-product could be used in e.g. fish farms.

Technical challenges


• No grid connection.

• Dynamic performance of electrolyser.

• Start-stop of electrolyser.

• Need for short-term energy storage (battery, flywheel…).

• Sizing of electrolyser, wind turbine and hydrogen storage.

• Design of power converters and control system.

Wind conditions in Norway


Weibul distribution for a year


Normal distribution for a day


Simulation case study


Input parameters

• 500 kW wind turbine• 3 hydrogen buses• Mean wind speed 7 m/s

Sizing results

• 80 kW electrolyser• 330 kWh lead-acid battery• 3300 kg hydrogen storage tank

Component data

Investment cost

O&M costEfficiency

Wind turbine 800 $/kW 2 % 100 %

El. energy storage

350 $/kW350 $/kWh

4 % 70 % a

Electrolyser 450 $/kW 4 % 4.5 kWh/Nm3

Compressor 2,000 $/kW 4 % 0.35 kWh/Nm3

Hydrogen storage

60 $/Nm3 2 % 100 %

Sensitivity of wind speed


7 7.5 8 8.5 9 9.51.4

1.6

1.8

2

2.2

2.4

2.6

2.8

Mean wind speed [m/s]

Hyd

roge

n co

st [

$/N

m3 ]

Sensitivity of lifetime


10 11 12 13 14 15 16 17 18 19 202.2

2.4

2.6

2.8

3

3.2

3.4

3.6

System operation period [years]

Hyd

roge

n co

st [

$/N

m3 ]

Conclusions and further work


• The method can be used for estimating the required component sizing for a specific hydrogen demand.

• The method shows good results when compared with chronological simulations.

• Further work will focus on improved rules for sizing of short-term storage.

• Further development of the model could include a more accurate representation of electrolyser and power convertes.

• The sizing priciples will also be used for isolated systems with stationary fuel cell.

a probabilistic method for sizing of isolated wind-electrolyser systems

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