production of hydrogen from renewable electricity: the electrolysis component workshop on...
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Production of Hydrogen from Renewable Electricity:
The Electrolysis ComponentWorkshop on Electrolysis Production of Hydrogen from Wind
and Hydropower
NREL DC Office, Sept 8,2003.
Renewable Electricity- Infrastructure
Meets DOE Hydrogen Feed Stock Strategy:
Primary Indigenous Sources: Wind, “run of river” hydro, solar No carbon-emissions in electricity-hydrogen generation Mature technology, established cost progression
But can we meet DOE cost target ?
$2.00 per kg at plant gate
Wind-Electrolysis Integration
Process Capabilities: > 90% of energy consumed by cells
(@ 20 bar) generator following load
trade off between efficiency and cap $. Efficiency inversely proportional to cell surface area (cap$).
design to avg efficiency/wind resource:
• Plant X = 53 kWh/kg• Plant 2X = 47.5 kWh/kg
“Current sink” characteristic Voltage regulated by cells Response like “leaky capacitor”
Value of by-products Electricity on demand Oxygen by-product @ $25 per tonne
= .4 cent per kWh D20 ?
Capacity Factor Matching(avg capacity=.40)
0102030405060708090
100
0 20 40 60 80 100
Cumulative Time < Rate (%)
Pro
du
ctio
n R
ate
(%
of
max
ou
tpu
t)
30
35
40
45
50
55
60
65
Cel
l E
ner
gy
Co
nsu
mp
tio
n R
ate
(kW
h/k
g)
Production Rate
Plant X$
Plant 2X$
Cost Target Implications
Simple Cost Model : $/kg = Efficiency(price of electricity) +
[Annual (CRF+O/M)] (Capital Cost per kg/h)÷ [(capacity factor) 8760 h/y]
Implications For Annual (CRF +O/M) =20% Capacity Factor = .35 Avg. Efficiency = 50 kWh/kg (=approx 80% wrt HHV)
Cost of Wind Electricity `2.5 ¢/kWh 3.0 ¢/kWh
Cost of Electrolyser (@ Avg Efficiency) $12,000/kg/h $8,000/kg/h
Two Market Models:
Wind-Hydrogen Generation Model
Wind- Hydrogen&Electricity Generation Model
Capacity Factor Matching in Wind-Hydrogen Generation Model
Single tier market design: Large-Scale Hydrogen Production
Tech Implications Power Conversion: Optimize
DC-Wind conversion based on electrolysis cells
Optimize cell size to scale of production – cell cost key
Maintaining grid stability with high electrolysis penetration
Pressurized cell design amenable to distribution pipeline
Capacity Factor Matching(avg capacity=.40)
0102030405060708090
100
0 20 40 60 80 100
Cumulative Time < Rate (%)
Pro
du
ctio
n R
ate
(%
of
max
ou
tpu
t)
30
35
40
45
50
55
60
65
Cel
l E
ner
gy
Co
nsu
mp
tio
n R
ate
(kW
h/k
g)
Production Rate
Plant X$
Plant 2X$
Capacity Factor Matching in Wind Hydrogen-Electricity Generation Model Two tier market design:
Primary Market : Electricity Secondary Market: Hydrogen
Deregulated electricity market design with environmental credits for emission avoidance
Capture distributed generation benefit Closer to market Higher value electricity market
supports secondary hydrogen production (energy storage)
Technology Implications Controls System Cost Key
Capacity Factor Matching(avg capacity=.40)
0102030405060708090
100
0 20 40 60 80 100
Cumulative Time < Rate (%)
Pro
du
ctio
n R
ate
(%
of
max
ou
tpu
t)
Wind Profile
Electric Power Limit
Cell Technology
Product Name Stuart Cell EI-250 M-Platform IMET
Cell Technology Unipolar Gen II Unipolar
Gen II
DEP Bipolar
Production Capacity
5 Nm3/h to 1000 Nm3/h
1000 Nm3/h and greater
50 Nm3/h and greater
1 Nm3/h to
100 Nm3/h
Cell Pressure Atmospheric Atmospheric Atmospheric up to 25 bars
Typical Application
Generator
Cooling
Hydrogen Peroxide
Fiber Optics Bus filling
station
Technical Challenges
Intermittent operation; long term electrode stability Economic scale of cell; cost highly dependant on cells Gas purity process dynamics:
Controlling gas/liquid separation Reducing bypass cell currents Cell pressurization
Power conversion & controls
Conclusions:
• DOE cost targets are very challenging
• Early pathways to develop infrastructure:
• Replace SMR hydrogen under right market conditions (NG conservation/CO2 mitigation):
• heavy oil upgrading
• ammonia production
• Distributed “hydrogen&electricity generation model” may play role in early infrastructure development – if value put on green electricity/green hydrogen.