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. 2022 May 16;51(11):4583–4762. doi: 10.1039/d0cs01079k

State-of-the-art and future key performance indicators (KPIs) for all electrolyser technologies. Adapted from IRENA225.

2022 Target 2050 R&D focus
PEM electrolysers
Nominal current density 1–3 A cm−2 4–6 A cm−2 Design, membrane
Voltage range (limits) 1.4–2.3 V <1.7 V Catalyst, membrane
Operating temperature 50–80 °C 80 °C Effect on durability
Cell pressure ≤50 bar >70 bar Membrane, rec. catalysts
Load range 5–130% 5–300% Membrane
H2 purity 99.9–99.9999% Same Membrane
Voltage efficiency (LHV) 50–68% >80% Catalysts
Electrical efficiency (stack) 47–66 kW h kgH2−1 <42 kW h kgH2−1 Catalysts/membrane
Electrical efficiency (system) 50–83 kW h kgH2−1 <45 kW h kgH2−1 Balance of plant
Lifetime (stack) 50 000–80 000 h 100 000–120 000 h Membrane, catalysts, PTLs
Stack unit size 1–2 MW 10 MW MEA, PTL
Electrode area ≤3000 cm2 >10 000 cm2 MEA, PTL
Cold start (to nom. load) <20 min <5 min Insulation (design)
Capital costs (stack) min 1 MW 400 USD kW−1 <100 USD kW−1 MEA, PTLs, BPs
Capital costs (system) min 10 MW 700–1400 USD kW−1 <200 USD kW−1 Rectifier, water purification
Alkaline electrolysers
Nominal current density 0.2–0.8 A cm−2 >2 A cm−2 Diaphragm
Voltage range (limits) 1.4–3 V <1.7 V Catalysts
Operating temperature 70–90 °C >90 °C Diaphragm, frames, BoP components
Cell pressure <30 bar >70 bar Diaphragm, cell, frames
Load range 15–100% 5–300% Diaphragm
H2 purity 99.9–99.9998% >99.9999% Diaphragm
Voltage efficiency (LHV) 50–68% >70% Catalysts, temp.
Electrical efficiency (stack) 47–66 kW h kgH2−1 <42 kW h kgH2−1 Diaphragm, catalysts
Electrical efficiency (system) 50–78 kW h kgH2−1 <45 kW h kgH2−1 Balance of plant
Lifetime (stack) 60 000 h 100 000 h Electrodes
Stack unit size 1 MW 10 MW Electrodes
Electrode area 10 000–30 000 cm2 30 000 cm2 Electrodes
Cold start (to nom. Load) <50 min <30 min Insulation (design)
Capital costs (stack) min 1 MW 270 USD kW−1 <100 USD kW−1 Electrodes
Capital costs (system) min 10 MW 500–1000 USD kW−1 <200 USD kW−1 Balance of plant
AEM electrolysers
Nominal current density 0.2–2 A cm−2 >2 A cm−2 Membrane, rec., catalyst
Voltage range (limits) 1.4–2.0 V <2 V Catalyst
Operating temperature 40–60 °C 80 °C Effect on durability
Cell pressure <35 bar >70 bar Membrane
Load range 5–100% 5–200% Membrane
H2 purity 99.9–99.999% >99.9999% Membrane
Voltage efficiency (LHV) 52–67% >75% Catalysts
Electrical efficiency (stack) 51.5–66 kW h kgH2−1 <42 kW h kgH2−1 Catalysts/membrane
Electrical efficiency (system) 57–69 kW h kgH2−1 <45 kW h kgH2−1 Balance of plant
Lifetime (stack) >5000 h 100 000 h Membrane, electrodes
Stack unit size 2.5 kW 2 MW MEA
Electrode area <300 cm2 1000 cm2 MEA
Cold start (to nom. Load) <20 min <5 min Insulation (design)
Capital costs (stack) min 1 MW Unknown <100 USD kW−1 MEA
Capital costs (system) min 1 MW Unknown <200 USD kW−1 Rectifier
Solid oxide electrolysers
Nominal current density 0.3–1 A cm−2 >2 A cm−2 Electrolyte, electrodes
Voltage range (limits) 1.0–1.5 V <1.48 V Catalysts
Operating temperature 700–850 °C <600 °C Electrolyte
Cell pressure 1 bar >20 bar Electrolyte, electrodes
Load range 30–125% 0–200% Electrolyte, electrodes
H2 purity 99.9% >99.9999% Electrolyte, electrodes
Voltage efficiency (LHV) 75–85% >85% Catalysts
Electrical efficiency (stack) 35–50 kW h kgH2−1 <35 kW h kgH2−1 Electrolyte, electrodes
Electrical efficiency (system) 40–50 kW h kgH2−1 <40 kW h kgH2−1 Balance of plant
Lifetime (stack) <20 000 h 80 000 h All
Stack unit size 5 kW 200 kW All
Electrode area 200 cm2 500 cm2 All
Cold start (to nom. Load) >600 min <300 min Insulation (design)
Capital costs (stack) min 1 MW >2000 USD kW−1 <200 USD kW−1 Electrolyte, electrodes
Capital costs (system) min 1 MW Unknown <300 USD kW−1 All