alkaline electrolyzer

Alkaline Hydrogen Electrolyzer (ALE) KPIs, BoP, Future Design, Hydrogen Production11

🟦 1) An Alkaline electrolyzer uses sodium or potassium hydroxide as the electrolyte to transport hydroxide ions from the cathode to the anode, generating hydrogen on the cathode side.

🟦 2) How do Alkaline Electrolysers work?
During an electrochemical reaction, a porous diaphragm uses an ionic charge carrier. To facilitate the reaction, KOH and water are used. However, the produced gases (H2 and O2) dissolve in the electrolyte, which limits the power range and makes it difficult to operate at higher pressure levels.

🟦 3) Cost breakdown for 1 MW alkaline electrolyzer:

3.1- Balance of Plant
Power Supply → 50%
Deionised Water Circulation → 22%
Hydrogen Processing → 20%
Cooling → 8%

3.2- Stack
Porous Transport Layer (PTLs) → 8%
Structural parts → 14%
Sealing, frames → 4%
Bipolar Plates (BPs) → 7%
Assembly and end plates → 10%
Diaphragm/ Electrode → 57%

🟦 4) Alkaline Hydrogen Electrolysers 2050 KPIs:

Nominal current density> 2A/cm2

Voltage range (limits)< 1.7V

Operating temp.> 90 °C

Cell pressure> 70bar

Load range= 5 %-300 %

H2 purity> 99.9999 %

Voltage efficiency [LHV]> 70 %

Electrical effi. [stack]< 42 kWh/Kg hydrogen

Electrical effi. [system]< 45 kWh/Kg hydrogen

Lifetime [stack]= 100,000h

Stack unit size= 10MW

Electrode area= 30,000cm²

Cold start [to nom. load]< 30min.

Capital costs [stack] min. 1 MW< USD100/kW Electrodes

Capital costs [system] min. 10 MW< USD200/kW BoP

✅ Reference for 1-4: Reference a (see attached image)

🟦 5) Atmospheric alkaline electrolyzer Balance of Plant:
- a KOH scrubber,
- stack feed surge drum,
- electrolyzer, and
- cathode effluent separator.

🟦 6) Process description:
- The stack works at ~30 bar pressure in a pressurised Alkaline electrolyser, eliminating a hydrogen gas compressor.

- The H2 purification subsystem removes O2 impurities using a deoxidizer and eliminates saturated water using a Temperature Swing Adsorption (TSA) subsystem.

- Two TSA adsorption beds remove water from the H2 stream to achieve 99.99 mol% H2 purity. The water is then fed back into the KOH scrubber.

🟦 7) Future Alkaline hydrogen electrolyzer designs:
- Diaphragm thickness reduction: 500 to 220 microns;
- The elastic element replacement to an open flow field;
- Component reduction;
- Cathode and Anode catalysts change from Nickel mesh to a NiAlMo coating (Nickel substrate);
- Nickel plates with etched flow fields bipolar change to flat Ni-coated stainless steel plates;
- Current Density change from 0.7 to 1 A/cm2;
- Cell Voltage changes from 2 to 1.7 V.

✅ Reference for 5-7: Reference b (see attached image)

🟦 8) Alkaline Electrolyzer OEMs:
Green Hydrogen System
Aquahydrex
Asahi Kasei
Cockerilll Jingli
Cummins 
Denora
Hydrogenpro
Kobelco 
Kumatec
Mcphy
Nel
Peric
Shanghai Zhizhen
Tianjin
Thyssenkrupp Uhde

✅ l My posts reflect my personal experience, knowledge, and advice.