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H2 Electrolyser

Screening-stage hydrogen electrolyser calculator with technology selector, nominal power and capacity factor; outputs hourly/annual H2, water feed, O2 co-product, CAPEX breakdown, and levelized cost of hydrogen (LCOH).

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alexi

I do low-carbon energy stuff for 10 years & build things I wish existed.

12

Basic Numbers

Select electrolyser type. Technology affects specific electricity consumption and reference CAPEX assumptions.

Total electrical input capacity of the electrolyser system (MW).

min 1 · max 1000 · step 1 · MW

Effective electricity consumption

Technology-specific specific consumption adjusted by capacity-factor penalty

…kWh/kg

Hydrogen production rate

Main product, while operating at nominal power

…kg/h

Hourly water requirement (volume)

Feedstock need per hour, converted to m3

…m3/h

Hourly oxygen co-production

O2 co-product per hour (stoichiometric)

…kg/h

Annual Balance

Average utilization over the year. Used to compute operating hours and annual production/consumption.

min 5 · max 100 · step 1 · %

Annual electricity consumption

Electrical input energy based on nominal power and capacity factor

…MWh/year

Annual hydrogen production

Main product, annualized by capacity factor

…kg/year

Annual operating hours (at capacity factor)

Used to annualize production and costs

…h/year

Annual water requirement

Feedstock need (make-up water), stoichiometric basis

…m3/year

Annual oxygen co-production

Co-product (if captured/purified); otherwise vented

…kg/year

Costs

Total project CAPEX (all-in)

Installed plant cost + indirects/owner costs (screening scope)

…EUR

Equipment purchase cost (EPC supply, excl. installation)

Electrolyser system package purchase only (screening)

…EUR

Installed plant cost (equipment + installation)

Excludes owner costs unless embedded in installation factor

…EUR

Scaled specific equipment CAPEX

Electrolyser package purchase cost intensity after scale curve and clamps

…EUR/kW
Scale effect

Log in to view this sensitivity chart.

Annualized CAPEX (CRF-based)

Total project CAPEX converted to an annual payment equivalent

…EUR/year

Equipment breakdown: stack share

Indicative allocation within equipment purchase cost

…EUR

Equipment breakdown: balance of plant (BoP) share

Indicative allocation within equipment purchase cost

…EUR

Equipment breakdown: power electronics share

Indicative allocation within equipment purchase cost

…EUR

Simple LCOH2

Average delivered electricity price to the electrolyser (all-in, as applicable).

EUR/MWh

Screening value for purified/industrial water. Stoichiometric water need is calculated; treatment losses are not modeled.

EUR/m3

Levelized cost of hydrogen (LCOH)

Total annual cost divided by annual H2 production

…EUR/kg

Economic lifetime for levelized cost calculation.

years

Used to compute CRF for annualizing CAPEX.

About

Calculator context

Introduction

This calculator estimates hydrogen (H2) production, electricity and water requirements, oxygen (O2) co-production, and screening-level CAPEX and LCOH for an electrolyser plant using a technology selector (PEM / Alkaline / AEM). It is scoped to the user’s operating context “Technology: hydrogen” and is intended for early project development decisions where only nameplate power, capacity factor, and a few commercial assumptions are known.

Methodology

The model combines a simplified energy balance, a stoichiometric mass balance, and a cost scaling + discounted cash-flow approach aligned with widely used pre-feasibility methods (e.g., IRENA technology briefs, IEA/NREL cost reporting conventions, and standard project finance practice).

Key steps and equations:

  • Operating hours: load_hours = hours_per_year × capacity_factor.
  • Part-load / utilization penalty: load_penalty = clamp(1 + penalty_coeff × (1 − capacity_factor), 1, max_penalty).
  • Effective electricity intensity: effective_consumption = specific_consumption × load_penalty, where specific_consumption is technology-dependent (kWh/kg H2).
  • H2 production:
    • H2_rate (kg/h) = power_kW / effective_consumption.
    • H2_annual (kg/y) = H2_rate × load_hours.
  • Mass balance (stoichiometry):
    • Water (kg) = water_per_h2 × H2 (kg).
    • O2 (kg) = o2_per_h2 × H2 (kg).
  • CAPEX (screening scale law):
    • specific_capex_scaled = clamp(specific_capex_ref × (P/P_ref)^(scale_exp − 1), min, max).
    • equipment_purchase_cost = specific_capex_scaled × P_kW.
    • installed_plant_cost = equipment_purchase_cost × (1 + installation_factor).
    • total_project_capex = installed_plant_cost × (1 + indirect_owner_factor).
  • Finance:
    • CRF = (r*(1+r)^n)/((1+r)^n−1).
    • annualized_capex = total_project_capex × CRF.
    • total_annual_cost = annualized_capex + fixed_O&M + electricity_cost + water_cost.
    • LCOH (EUR/kg) = total_annual_cost / H2_annual.

Applications

  • Business developer: compare PEM vs Alkaline vs AEM at a given grid price and capacity factor to screen for lowest LCOH.
  • Project origination / partnerships: quantify annual H2 supply and O2 co-product volume for offtake discussions.
  • Early engineering/commercial alignment: sanity-check CAPEX scale effects (equipment vs installed vs all-in project CAPEX) before launching a detailed study.

Model

81 variables — inputs, calculations and outputs, with their dependencies.

81 variables shown of 81
VariableValueUnitDepends on
1——
50MW—
90%—
60EUR/MWh—
1.5EUR/m3—
0.08ratio—
20years—
VariableFormulaUnitDepends on
if((<=0)+(<0)+(>100)+(<0)+(<0)+(<0)+(<=0)+(<)+(>)>0,1,0)bool
*kW
clamp(+*(-*0.01),,)—
if(==,,if(==,,))kWh/kg
*MWh/h
*kg/year
if(==,,if(==,,))EUR/kW
if(==,,if(==,,))—
*(/max(,))^(-)EUR/kW
if(==,,if(==,,))1/year
*(/max(,))^()1/year
clamp(,,)1/year
(*(1+)^)/max(((1+)^-1),)—
*EUR/year
*EUR/year
*EUR/year
VariableFormulaUnitDepends on
**0.01h/year
*kWh/kg
/max(,)kg/h
*kg/year
*MWh/year
*kg/h
/max(,)m3/year
/max(,)m3/h
*kg/h
*kg/year
clamp(,,)EUR/kW
*EUR
*EUR
*EUR
*EUR
*(+)EUR
*(+)EUR
*EUR/year
+++EUR/year
/max(,)EUR/kg

Assumptions

38 assumptions used in the calculations

  • Prevents division-by-zero and NaN propagation in edge cases.

    Market range Not applicable (numerical parameter).

    0.000001
    Numerical stability constant for division guards.

  • Used for capacity-factor annualization.

    Market range 8760 (non-leap year); 8784 (leap year).

    8760h/year
    Calendar-year hours convention.

  • Converts MW to kW for kWh/kg calculations.

    Market range Exact.

    1000kW/MW
    Unit conversion.

  • Converts water mass to volume for reporting.

    1000kg/m3
    Approximate density of water near ambient conditions.

  • 2H2O → 2H2 + O2 implies 18 g water per 2 g H2.

    Market range 9 (stoichiometric); higher if including purification and blowdown losses.

    9kg water/kg H2
    Stoichiometry of water electrolysis.

  • 2H2O → 2H2 + O2 implies 32 g O2 per 4 g H2.

    Market range 8 (stoichiometric).

    8kg O2/kg H2
    Stoichiometry of water electrolysis.

  • Represents efficiency degradation and non-ideal operation at lower utilization in a simple way.

    0
    Screening utilization/part-load penalty coefficient.

  • Prevents penalty from improving performance below the reference specific consumption.

    Market range 1 (by definition).

    1
    Clamp lower bound for penalty factor.

  • Avoids unrealistically large penalties at low capacity factors in a screening model.

    1.35
    Clamp upper bound for penalty factor.

  • Required because DSL has no strings.

    Market range Not applicable.

    1
    Numeric selector encoding.

  • Required because DSL has no strings.

    Market range Not applicable.

    2
    Numeric selector encoding.

  • Required because DSL has no strings.

    Market range Not applicable.

    3
    Numeric selector encoding.

  • Avoids inline literals in DSL expressions per spec.

    Market range Exact.

    1
    Numeric constant.

  • Validates selector domain.

    1
    Input validation bound.

  • Validates selector domain.

    3
    Input validation bound.

  • Screening mid-point for modern PEM systems including balance-of-plant loads.

    54kWh/kg
    Representative specific electricity consumption (LHV basis implied) for PEM electrolyser.

  • Screening mid-point for modern AEL systems.

    52kWh/kg
    Representative specific electricity consumption for alkaline electrolyser.

  • AEM is emerging; value set conservatively for screening.

    56kWh/kg
    Representative specific electricity consumption for AEM electrolyser.

  • Provides a consistent anchor for scaling specific CAPEX with size.

    20000kW
    Reference size for scale curve.

  • Screening mid-range for PEM system purchase costs.

    1100EUR/kW
    Reference equipment purchase cost intensity for PEM at reference size.

  • Screening mid-range for alkaline systems.

    850EUR/kW
    Reference equipment purchase cost intensity for AEL at reference size.

  • Emerging technology; set conservatively for screening.

    1300EUR/kW
    Reference equipment purchase cost intensity for AEM at reference size.

  • Represents economies of scale for packaged systems.

    0.85
    Scale exponent for PEM equipment costs.

  • Represents economies of scale for packaged systems.

    0.85
    Scale exponent for AEL equipment costs.

  • Emerging technology; assumed slightly weaker economies of scale.

    0.9
    Scale exponent for AEM equipment costs.

  • Prevents unrealistically low specific costs due to scaling outside intended range.

    400EUR/kW
    Clamp minimum for scaled specific CAPEX.

  • Prevents unrealistically high specific costs due to scaling outside intended range.

    2500EUR/kW
    Clamp maximum for scaled specific CAPEX.

  • Represents installation labor, foundations, cabling, piping, and commissioning at screening level.

    0.35
    Installation and construction factor applied to equipment purchase cost.

  • Approximates engineering, permitting, contingency, owner's costs, and development costs.

    0.2
    Indirect + owner costs factor on installed plant cost.

  • Represents routine maintenance, staffing, and service agreements at screening level.

    0.041/year
    Fixed O&M fraction of total project CAPEX (PEM).

  • Screening assumption; alkaline maintenance cost may be somewhat lower in some service models.

    0.031/year
    Fixed O&M fraction of total project CAPEX (AEL).

  • Emerging technology; assumed higher service/maintenance burden at screening stage.

    0.051/year
    Fixed O&M fraction of total project CAPEX (AEM).

  • Represents mild economies of scale in fixed O&M overheads.

    Market range -0.15 to 0.

    -0.05
    Scale effect on O&M fraction.

  • Prevents implausibly low O&M fractions in large-scale cases.

    0.0151/year
    Clamp minimum for O&M fraction.

  • Prevents implausibly high O&M fractions from scaling artifacts.

    0.081/year
    Clamp maximum for O&M fraction.

  • Represents stack as the dominant cost component in many electrolysers.

    0.55
    Equipment cost allocation share.

  • Captures pumps, piping, cooling, gas-liquid management, controls, etc.

    0.3
    Equipment cost allocation share.

  • Represents rectifier / power electronics package share of equipment cost.

    0.15
    Equipment cost allocation share.