Water Electrolysis Application#

Question 1

What are the options for water electrolysis?

Answer 1

• Alkaline electrolysis Liquid electrolyte (KOH) (40-90 C)
• PEM - electrolysis Polymer Electrolyte (20-100 C)
• High temperature electrolysis Ceramic electrolyte (700-1000 C)

Question 2

What is the charge carrier in Alkaline electrolysis?

Answer 2

OH- from cathode to anode

Question 3

What is the charge carrier in PEM Electrolysis?

Answer 3

H+ from anode to cathode

Question 4

What is the charge carrier in HT Electrolysis?

Answer 4

O2- from cathode to anode

Question 5

What are some properties of Alkaline electrolysis?

Answer 5

Mature technology, ~10 years lifetime
<2.2 MW stacks / plants <156 MW
No precious metal catalysts
Little exper. in dynamic operation
Shunt current required
Cost 300-500 $/kW (NREL)

Question 6

What are some properties of PEM electrolysis?

Answer 6

Demonstration / market entry
up to 10 MW units
Pt and Ir as catalysts
Dynamic operation possible
Simple plant design
Projected cost 300-500 $//€ per kW

Question 7

What are some properties of HT electrolysis?

Answer 7

Laboratory stage
kW stage
Ni catalysts / perovskite catalysts
Dynamic operation possible
High potential for overload
High efficiency; no cost information

Question 8

What is the process chart of a PEM Electrolyser unit?

Answer 8

• AC power (from outside)
• Rectifier
• PEM Electrolyser
• Gas dryer
• H2 compressor
• Pressure tank for storage (outside)