Open Source Electrolyzer

https://chatgpt.com/share/69b78df5-6188-8010-8d76-08b5073da11a

No Exotic Materials Required

No exotic manufacturing is required - no exotic membranes outside of off-the-shelf Zirfon separator which appears to contribute 10% to the cost.

$10-20k for a 100kW stack. Payback of one year with 6 hour solar, quicker with wind.

Materials Breakdown and Sourcing

100 kW Open Source Alkaline Electrolyzer Stack – Bill of Materials

Component	Specification	Quantity	Typical Cost Range	Example Supplier / Source	Link
Nickel Foam (Cathode)	1–2 mm thick, 20–60 PPI, >99% Ni	~12 m²	$300–$1,500	MTI Corporation	https://mtixtl.com/products/0-5-mm-thick-nickel-foam-for-battery-cathode-substrate-or-solid-state-electrolyte-support-l-1000-x-w-200-mm-eq-bcnf-05m
Nickel Foam (Anode substrate)	same spec as cathode	~12 m²	$300–$1,500	Goodfellow	https://www.goodfellow.com/usa/nickel-sizes-foam-group
Separator (Zirfon-type diaphragm)	~0.3–0.5 mm polysulfone + zirconia composite	~12 m²	~$1,800	Agfa Zirfon PERL	https://www.agfa.com/zirfon/
Cell Frames / Spacers	HDPE / polypropylene plates	~100 pieces	$500–$1,500	McMaster-Carr plastic sheet	https://www.mcmaster.com/polypropylene-sheets/
End Plates	Carbon steel or stainless plate	2 pieces	$200–$600	Online Metals steel plate	https://www.onlinemetals.com/
Gaskets	EPDM or PTFE sheet 1–2 mm	~100 sets	$100–$400	McMaster-Carr gasket sheet	https://www.mcmaster.com/epdm-rubber/
Current Collectors	Nickel sheet or nickel mesh	~2–4 m²	$200–$800	Alfa Aesar nickel sheet	https://www.fishersci.com/shop/products/nickel-foil/AA43098
Busbars	Copper bar stock	~3–5 kg	$100–$300	McMaster copper bar	https://www.mcmaster.com/copper-bars/
Electrolyte	Potassium hydroxide (KOH), 25–30 wt%	~100–150 L solution	$200–$500	Lab Alley KOH	https://www.laballey.com/products/potassium-hydroxide-koh
Anode Catalyst Bath Chemical	Nickel sulfate (NiSO₄)	~1–2 kg	$50–$200	Sigma-Aldrich	https://www.sigmaaldrich.com/US/en/product/aldrich/656895
Anode Catalyst Bath Chemical	Ferrous sulfate (FeSO₄)	~1 kg	$20–$80	Fisher Scientific	https://www.fishersci.com/shop/products/ferrous-sulfate-heptahydrate
Anode Catalyst Bath Chemical	Boric acid (H₃BO₃)	~1 kg	$10–$40	Sigma-Aldrich	https://www.sigmaaldrich.com/US/en/product/sial/695092

Summary of Major Materials

100 kW Open Source Alkaline Electrolyzer Stack Summary

Material	Amount
Nickel foam	~24 m² total
Zirfon separator	~12 m²
Plastic frames	~100
Steel end plates	2
Gaskets	~100 sets
KOH electrolyte	~100–150 L

Corrected Stack Materials and Fabrication Budget (100 kW Alkaline Electrolyzer)

Detailed Stack Cost Breakdown (Prototype-Realistic)

Category	Description	Estimated Cost Range
Nickel Foam Electrodes	Cathode + anode substrate (~24 m² total)	$600–$3,000
Separator (Zirfon)	~12 m² diaphragm material	~$1,800
Electrolyte + Chemicals	KOH + NiSO₄ + FeSO₄ + boric acid	$200–$600
Gaskets	~100 cell gasket sets (EPDM/PTFE)	$150–$500
Plastic Frame Stock	HDPE/PP sheets for ~100 frames	$400–$1,200
Current Collectors + Busbars	Nickel sheets/mesh + copper busbars + terminals	$500–$2,000
End Plates + Compression Hardware	Steel plates, tie rods, bolts, springs	$500–$2,000
Fabrication + Machining	CNC cutting, drilling, finishing of frames and plates	$1,000–$3,000
Scrap, Yield Loss, Shipping, Contingency	Material losses, damaged parts, supplier overhead	$1,500–$4,000
Total Estimated Stack Cost (Corrected)	Prototype-scale, materials + fabrication	$6,650 – $19,100

Interpretation

Layer	Meaning	Cost Range
Raw materials only	Just purchased materials without fabrication overhead	~$3,600 – $8,400
Practical prototype build	Includes machining, scrap, and assembly realities	~$6,500 – $15,000 (typical target)
High-friction prototype case	Inefficient sourcing, mistakes, iteration cycles	Up to ~$19,000

Key Insight

The earlier mismatch came from mixing two different accounting layers:

• The visible table showed mostly **raw materials**
• The total implicitly included **fabrication, waste, and prototype inefficiencies**

A correct engineering budget must explicitly include:

• manufacturing steps (cutting, machining, assembly)
• process losses (scrap, rework)
• procurement overhead (shipping, minimum orders)
• structural components (compression system, busbars)

Without these, the estimate will systematically understate real build cost.

For planning purposes:

• **Use ~$7k–$15k as a realistic first prototype stack target**
• Expect cost reduction only after:

 * volume purchasing
 * simplified geometry
 * process standardization

Balance of System

(includes PV)

100 kW Open Source Alkaline Electrolyzer Balance-of-System Budget

Balance-of-System Cost Breakdown (Prototype-Realistic, 100 kW)

Category	Description	Estimated Cost Range	Notes
Power electronics / DC current control	Rectifier or DC/DC current controller, bus protection, contactors	$6,000–$15,000	Largest BoS bucket; aligns with IRENA showing power supply as the dominant BoP element
Water treatment + make-up water	Pre-filtration, deionized water handling, make-up tank	$500–$2,000	Needed to maintain electrolyte quality and reduce contamination
Electrolyte circulation loop	Electrolyte reservoir, alkali-compatible pumps, recirculation piping	$2,000–$6,000	Corresponds to the circulation/process side of alkaline BoP
Cooling system	Heat exchanger, auxiliary pump, radiator or water cooling loop	$1,500–$5,000	Removes waste heat from stack/electrolyte loop
Gas-liquid separators	Hydrogen-side and oxygen-side knockout / separator vessels	$1,500–$4,000	First cleanup stage after stack
Demister + coalescing filters	Mist eliminators and particulate protection	$500–$2,000	Minimal gas cleanup for non-fuel-cell use
Gas drying	Desiccant dryer or twin-tower dryer	$2,000–$6,000	Required for robust storage and downstream engine use
Optional deoxo unit	Oxygen removal reactor for cleaner hydrogen	$0–$6,000	Optional for ICE use; more important for higher-purity gas service
Compression and storage	Cylinder manifold, regulators, 30 cylinders at ~1 kg each	~$10,000	Based on current project assumption
Piping, valves, fittings	Stainless / nickel-compatible plumbing, isolation valves, check valves	$2,000–$6,000	Usually underestimated in first-pass budgets
Sensors + safety hardware	Pressure, temperature, flow, level, H2 detection, relief valves, vents	$2,000–$6,000	Essential for safe operation
Controls + wiring	PLC / controller, relays, HMI, low-voltage wiring, interlocks	$2,000–$8,000	Includes startup/shutdown logic and safeties
Structural integration	Skid, mounting frame, panel enclosure, equipment supports	$2,000–$8,000	The main “system integration” bucket
Assembly, commissioning, and contingency	Final integration overhead, rework, consumables, prototype inefficiency	$3,000–$10,000	Captures first-build friction realistically
Total BoS excluding renewable power source	All non-stack systems around the electrolyzer	$35,000–$84,000	Typical practical target: about $45,000–$65,000

Optional External Energy Supply Hardware

Renewable Power Source (Outside Electrolyzer BoS Proper)

Category	Description	Estimated Cost	Notes
Solar or wind supply hardware	Example user assumption for 100 kW renewable input hardware	~$20,000	This is usually treated as external generation plant, not electrolyzer BoS

Combined System View

100 kW System-Level Capital Picture

Major Block	Estimated Cost Range
Electrolyzer stack	$6,650–$19,100
Balance of system (excluding renewable source)	$35,000–$84,000
Renewable power hardware	~$20,000
Total system including stack + BoS + renewable source	~$61,650 – $123,100

100 kW Open Source Alkaline Electrolyzer Balance-of-System Budget (Direct DC from PV, PV Source Excluded)

Balance-of-System Cost Breakdown (Prototype-Realistic, 100 kW, Direct DC Input)

Category	Description	Estimated Cost Range	Notes
DC input conditioning / current control	DC bus protection, MPPT interface or DC/DC current controller, contactors, breakers	$3,000–$10,000	Lower than AC-rectified systems because front-end rectifier/inverter hardware is reduced or eliminated
Water treatment + make-up water	Pre-filtration, deionized water handling, make-up tank	$500–$2,000	Needed to maintain electrolyte quality and reduce contamination
Electrolyte circulation loop	Electrolyte reservoir, alkali-compatible pumps, recirculation piping	$2,000–$6,000	Main liquid-process loop for stack operation
Cooling system	Heat exchanger, auxiliary pump, radiator or water cooling loop	$1,500–$5,000	Removes waste heat from stack/electrolyte loop
Gas-liquid separators	Hydrogen-side and oxygen-side knockout / separator vessels	$1,500–$4,000	First cleanup stage after stack
Demister + coalescing filters	Mist eliminators and particulate protection	$500–$2,000	Minimal gas cleanup for non-fuel-cell use
Gas drying	Desiccant dryer or twin-tower dryer	$2,000–$6,000	Required for robust storage and downstream engine use
Optional deoxo unit	Oxygen removal reactor for cleaner hydrogen	$0–$6,000	Optional for ICE use; more important for higher-purity gas service
Compression and storage	Cylinder manifold, regulators, 30 cylinders at ~1 kg each	~$10,000	Based on current project assumption
Piping, valves, fittings	Stainless / nickel-compatible plumbing, isolation valves, check valves	$2,000–$6,000	Usually underestimated in first-pass budgets
Sensors + safety hardware	Pressure, temperature, flow, level, H2 detection, relief valves, vents	$2,000–$6,000	Essential for safe operation
Controls + wiring	PLC / controller, relays, HMI, low-voltage wiring, interlocks	$2,000–$8,000	Includes startup/shutdown logic and safeties
Structural integration	Skid, mounting frame, panel enclosure, equipment supports	$2,000–$8,000	Main mechanical integration bucket
Assembly, commissioning, and contingency	Final integration overhead, rework, consumables, prototype inefficiency	$3,000–$10,000	Captures first-build friction realistically
Total BoS excluding PV source and excluding stack	All non-stack systems around the electrolyzer	$32,000–$79,000	Typical practical target: about $40,000–$55,000

Combined System View

100 kW System-Level Capital Picture (PV Source Excluded)

Major Block	Estimated Cost Range
Electrolyzer stack	$6,650–$19,100
Balance of system (direct DC from PV, excluding PV source)	$32,000–$79,000
Total system excluding PV source	$38,650 – $98,100

Interpretation

Using direct DC from PV reduces balance-of-system cost mainly by shrinking or eliminating the conventional AC rectifier stage.

The major remaining non-stack cost items are still:

• DC current control and protection
• gas handling and drying
• piping, sensors, and safety systems
• structural integration and commissioning

The main economic insight is that even with a DC-native architecture, the non-stack BoS remains larger than the stack cost for a prototype-scale 100 kW unit.

A good first-pass planning target is:

• stack: about $7k–$15k
• BoS excluding PV source: about $40k–$55k
• total excluding PV source: about $47k–$70k

Interpretation

The dominant non-stack cost items are typically:

• power electronics / current control
• gas handling and drying
• piping, sensors, and safety systems
• structural integration and commissioning

The major insight is that for a 100 kW distributed alkaline system, the stack is not the only serious cost center. The non-stack systems can readily exceed stack cost, which is consistent with current alkaline system cost structure where BoP remains a very large share of total electrolyzer CAPEX. Representative 2025 European electrolyzer cost reporting still separates cost into stack, balance of plant, other utilities, and other CAPEX, confirming that non-stack categories remain economically significant. :contentReference[oaicite:1]{index=1}