EngiMetric

EngiQuest / Process and energy systems

Green Hydrogen Plant

Size a screening electrolyzer plant from a written design basis through water, electricity, mass and energy balance, compression, storage and a limitation-aware screening-level annualized hydrogen cost.

  • Advanced
  • 15 stages
  • 205 min
  • Process and energy systems
In development All EngiQuest journeys
Draft development workbench (noindex). These stages are exercisable on a direct development route for learning and review. The journey remains a draft: not published, excluded from search/sitemap by existing protections, and not independently engineering-approved. Quantitative outputs are screening/educational where implemented and must not be treated as certified design, OEM guarantees, project approval, or bankable results.
Professional review required.Engines and workbench are implemented for draft development use. Defaults, sources, heating-value basis and engineering assumptions still require independent review. The journey must not be published or sitemap-indexed from this phase. Current verification state: Needs engineering review.

The engineering outcome

Process and energy systems

A fifteen-stage draft workbench for a coastal teaching case. You own the daily hydrogen target, technology label, stack specific electricity, water recovery, power contract, compression and storage windows, and unit rates. One saved state recomputes production, mass, water, energy, power, cost, scenarios and the exported report. Stack power, plant auxiliaries and compression/conditioning power stay separate.

Who it is for
Process, water and energy engineers working on power-to-hydrogen feasibility and front-end screening who need a traceable first-pass balance rather than a vendor quotation.
Stages
15
Estimated time
205 min
Level
Advanced

What you will be able to do

Learning objectives
  • Write a design basis that separates owner targets, illustrative assumptions, missing site data and professional-review requirements.
  • Relate stack capacity, specific electricity and operating hours to delivered hydrogen without mixing stack and plant power.
  • Close a stoichiometric water, hydrogen and oxygen mass balance, then add treatment recovery and process-water allowances.
  • Keep stack electricity, balance-of-plant, compression, conditioning and cooling auxiliaries distinguishable.
  • Screen compression duty and a 24-hour storage cycle against a stated delivery window.
  • Build a screening-level annualized hydrogen cost (screening LCOH) with electricity-price, utilisation and CAPEX sensitivities, and export a limitation-aware report.

Journey map

Ordered stages
  1. Write the project basis Fix the hydrogen target, technology label, operating calendar, availability and study boundary before any rate is computed. Introduction / 12 min
  2. Choose the electrolyzer technology label Compare PEM, alkaline and SOEC as labelled screening envelopes, not as vendor selections. Comparison / 12 min
  3. Size production against stack capacity Turn the daily target and stack capacity into delivered kilograms without exceeding the installed stack. Calculation / 16 min
  4. Close the plant mass balance Close stoichiometric water, hydrogen and oxygen flows from the delivered hydrogen rate. Calculation / 12 min
  5. Screen water demand and treatment recovery Convert stoichiometric water into treated demand, raw-water withdrawal, reject and a buffer volume. Calculation / 14 min
  6. Balance renewable and grid electricity Match annual plant energy to renewable generation and grid import without confusing energy with peak power. Calculation / 14 min
  7. Screen compression and gas conditioning Estimate multi-stage compression power and keep conditioning auxiliary power explicit. Calculation / 16 min
  8. Size the daily storage cycle Turn production and delivery windows into a working inventory, safety buffer and ideal-gas vessel volume. Calculation / 14 min
  9. Decide the oxygen interface Treat oxygen as a co-product with a stated fate, not as a silent vent or an automatic credit. Decision / 10 min
  10. Account for plant utilities and cooling Show balance-of-plant and cooling auxiliary power as explicit utilities, not as a hidden adder on stack kWh/kg. Calculation / 12 min
  11. Close the plant energy performance Add stack, BOP, compression, conditioning and cooling into one plant kW and one system kWh/kg. Calculation / 14 min
  12. Build a screening-level annualized hydrogen cost Assemble CAPEX and OPEX from editable unit rates and report a pre-tax, pre-revenue LCOH. Calculation / 16 min
  13. Re-run the plant through scenarios Compare demand, tariff, capacity, water recovery, renewable factor and delivery-window variants using full model re-runs. Comparison / 14 min
  14. Record missing studies and review items List the studies, permits and professional reviews that the screening model does not replace. Implementation / 12 min
  15. Defend the screening case and export the report Integrate the stages into a defended screening argument and export the same model the workbench shows. Capstone / 17 min

Before you start

Prerequisites
  • Comfort with kg, kg/h, kW, kWh, bar and the difference between stack and plant boundaries.
  • Electrolysis fundamentals for PEM, alkaline or solid-oxide labels.
  • Willingness to read failed checks instead of treating a summary as a design approval.

Defend the green-hydrogen screening case

Capstone

Produce an integrated screening review for the plant. Use the saved project state, the single engineering model and the failed-check register. The defence must keep stack power, plant auxiliaries and compression/conditioning power separate, and it must say what the model does not prove.

Deliverable
A written screening review of 1,000–1,800 words plus the exported Markdown or JSON report and a one-page missing-study register.
Evidence model
Rubric against produced artifacts, not completion ticks

Requirements

  • State the hydrogen target, technology label, operating calendar and which values are still illustrative.
  • Present delivered production, stack power and any shortfall without mixing in BOP.
  • Show stoichiometric mass closure and the additional water withdrawal from recovery and process allowance.
  • Report stack, BOP, compression, conditioning and cooling power as separate terms, then the plant total.
  • State compression duty, storage inventory and oxygen fate.
  • Present LCOH with currency, discount rate, life and the dominant sensitivity.
  • Identify the limiting constraint, open warnings and required professional reviews.

Rubric

Each criterion is scored from evidence, and weights sum to 100.
Weight Criterion Evidence
12% Design basis and labelled assumptions Owner targets, illustrative defaults, missing data and review needs are separated.
12% Production and stack boundary Delivered mass, stack kW and stack kWh/kg are consistent and not mixed with plant auxiliaries.
14% Mass and water balance Stoichiometry closes; raw-water withdrawal includes recovery and process allowance.
16% Energy boundary and distinguishable power Stack, BOP, compression, conditioning and cooling are reported separately and sum to plant power.
12% Compression, storage and oxygen interface Delivery pressure, inventory and oxygen fate are stated with their method limits.
12% Screening LCOH Cost uses model quantities and editable rates; no oxygen credit or revenue is implied.
14% Limitations and professional review Failed checks, missing studies and the required reviewer are named.
8% Clarity and unit consistency The argument is structured, unit-consistent and free of unsupported claims.
What this is not. This is an educational screening review, not a stamped design, FEED package, permit, offtake contract or investment case.

Replace illustrative water, grid, renewable, cost and technology values with evidenced project data, then re-run the model and the review.

Journey limits and sources

Provenance

Limitations

  • Status is draft. Direct development routes are noindex and must not enter the sitemap until a separate readiness assessment.
  • The workbench is a screening tool. It does not perform polarisation curves, compressor maps, vessel codes, HAZOP, interconnection studies or water-treatment design.
  • Stack, BOP, compression, conditioning and cooling powers are distinguishable, but rectifier, transformer and grid losses are included only if entered as BOP.
  • LCOH is pre-tax, pre-revenue and has no oxygen credit. Unit rates are illustrative.
  • Heating values, gas constant and heat-capacity ratio are screening constants, not a measured gas analysis.
  • Existing water/desalination engines are not bound to this electrolyzer envelope.
  • No safety-case, hazardous-area or permitting content is implemented.

Review status

  • Needs engineering review
  • Professional review is required before publication or use as a design basis.