Ways to make Steam

9 routes in the Atlas, side by side per the same functional unit. Whether they compare is computed from their data, criterion by criterion; a warning sits next to each route it concerns.

Not comparable as they standAllocation: differs; System boundary: differs; Data quality (TfS DQR): differs; Functional unit: differs; Reference product (grade, state): differs; System model: not stated by every route. The rows say which route each warning concerns.

Per 1 kg of Steam: inventory from each route's LCI dataset, unallocated; footprints per the functional unit of their own LCA.

Route	Tier, design maturity, review status	Geography, year	Energy	Feedstocks	Key emissions	Footprint	Comparability
Ammonia from natural gas (1500 t/d, steam reforming with air-fed secondary reformer, Haber-Bosch loop)steam methane reforming with air-blown secondary reformer, HT/LT shift, aMDEA CO2 removal (CO2 vented), methanation, 150 bar Haber-Bosch loop with purge recovery; electric drives, MP steam export	flowsheet or hand-writtenDesign maturity: Concept (research)Not independently reviewedDataset review: unreviewed	NL, 2026	a co-product of a multi-output dataset (product:NH3 besides it): its share needs the allocation of the LCI database build			no footprint	Reference product (grade, state): product is no grade (basis mole, component H2O, pressure 46.0, purity 1.0, temperature 400.0); the routes state no grade (basis mole, component H2O, pressure 43.0, purity 1.0, temperature 400.0), no grade (basis mole, component H2O, pressure 46.0, purity 1.0, temperature 400.0), steam/mp-11bara (component H2O, grade saturated steam, 11 bar(a), phase gas, pressure 11.0, temperature 184.06) Functional unit: functional unit is 1 kg; the routes state 1 kWh, 1 kg Allocation: allocation is exergy; most routes: shares
Aniline by adiabatic gas-phase hydrogenation of nitrobenzene (25 t/h)not stated	–Design maturity: Concept (research)Not independently reviewedDataset review: not stated	generic	no LCI dataset of this product			no footprint	Reference product (grade, state): states no product Functional unit: states no functional unit System boundary: states no boundary System model: states no system model Allocation: states no allocation Data quality (TfS DQR): states no data quality rating (TfS DQR)
Ethylene and propylene by ethane steam cracking (1000 kt/a ethylene, concept)not stated	–Design maturity: Concept (research)Not independently reviewedDataset review: not stated	generic	no LCI dataset of this product			no footprint	Reference product (grade, state): states no product Functional unit: states no functional unit System boundary: states no boundary System model: states no system model Allocation: states no allocation Data quality (TfS DQR): states no data quality rating (TfS DQR)
Hydrogen by natural-gas steam methane reforming with PSA (100 000 Nm3/h, steam export)natural-gas steam methane reforming, top-fired tubular reformer, HT shift, hydrogen PSA, tail gas firing, steam export; 100 000 Nm3/h	flowsheet or hand-writtenDesign maturity: Concept (research)Not independently reviewedDataset review: unreviewed	generic, 2026	a co-product of a multi-output dataset (product:H2 besides it): its share needs the allocation of the LCI database build			no footprint	Reference product (grade, state): product is no grade (basis mole, component H2O, pressure 43.0, purity 1.0, temperature 400.0); the routes state no grade (basis mole, component H2O, pressure 43.0, purity 1.0, temperature 400.0), no grade (basis mole, component H2O, pressure 46.0, purity 1.0, temperature 400.0), steam/mp-11bara (component H2O, grade saturated steam, 11 bar(a), phase gas, pressure 11.0, temperature 184.06) Functional unit: functional unit is 1 kg; the routes state 1 kWh, 1 kg Allocation: allocation is exergy; most routes: shares Data quality (TfS DQR): DQR 3.0002 is more than 1 above the best route's 1.6667
Hydrogen chloride synthesis burner and absorption (33 wt-% hydrochloric acid, steam recovery)HCl synthesis burner with steam-raising furnace (1000 kPa(a)), graphite falling-film absorber and water tail gas scrubber; 26.4 kt/a HCl as 33 wt-% acid; chlorine and hydrogen from an adjacent membrane-cell chlor-alkali plant	flowsheet or hand-writtenDesign maturity: Concept (research)Not independently reviewedDataset review: unreviewed	GLO, 2026	a co-product of a multi-output dataset (product:HCLACID besides it): its share needs the allocation of the LCI database build			no footprint	Reference product (grade, state): states no product Functional unit: functional unit is 1 kWh; the routes state 1 kWh, 1 kg
Hydroxylammonium sulfate by catalytic NO hydrogenation (30 kt/a NH2OH, 25 wt% solution)NH3 oxidation with O2 and steam on Pt/Rh (about 130 kPa(a)), O2 removal by hydrogenation, condensation, NO hydrogenation in about 20 wt% H2SO4 on suspended Pt/graphite in a stirred-tank cascade (313 K, 200 kPa(a)) with off-gas recycle and purge to a thermal oxidiser; 30 kt/a NH2OH	flowsheet or hand-writtenDesign maturity: Concept (research)Not independently reviewedDataset review: unreviewed	GLO, 2026	a co-product of a multi-output dataset (product:PROD besides it): its share needs the allocation of the LCI database build			no footprint	Reference product (grade, state): states no product Functional unit: functional unit is 1 kWh; the routes state 1 kWh, 1 kg
Weak nitric acid by dual-pressure ammonia oxidation (1000 t/d HNO3 as 60 wt% acid)dual-pressure ammonia oxidation (0.5 / 1.1 MPa(a)) over Pt/Rh, heat recovery to HP steam, absorption to 60 wt% HNO3, tertiary N2O decomposition and SCR, tail-gas expander; 1000 t/d HNO3	flowsheet or hand-writtenDesign maturity: Concept (research)Not independently reviewedDataset review: unreviewed	GLO, 2026	a co-product of a multi-output dataset (product:ACID besides it): its share needs the allocation of the LCI database build			no footprint	Reference product (grade, state): states no product Functional unit: functional unit is 1 kWh; the routes state 1 kWh, 1 kg
Solid sodium cyanide from Andrussow HCN (6.25 t/h, 50 kt/a)not stated	–Design maturity: Concept (research)Not independently reviewedDataset review: not stated	generic	no LCI dataset of this product			no footprint	Reference product (grade, state): states no product Functional unit: states no functional unit System boundary: states no boundary System model: states no system model Allocation: states no allocation Data quality (TfS DQR): states no data quality rating (TfS DQR)
Steam generation, natural-gas boiler, saturated 11 bar(a)natural-gas fired packaged steam boiler below 100 MMBtu/h heat input (ASSUMED class; about 30.7 t/h of steam at 3.2551 MMBtu HHV per t), no NOx control, no economiser credit, no condensate returnsteam/mp-11bara	Tier 1 (sourced conceptual)Design maturity: Concept (research)Not independently reviewedDataset review: unreviewed	GLO, 2026	Natural gas (as methane) to the burner: 0.0619 kg Feed pump and forced-draught fan: 0.0016 kWh	Boiler feedwater (demineralised make-up, no condensate return): 1.04 kg Combustion oxygen, from ambient air: 0.247 kg (free) Nitrogen fixed as NOx and N2O, from ambient air: 0.0000461 kg (free)	CO2 from combustion: 0.17 kg Water vapour from combustion: 0.139 kg NOx from combustion, as NO2: 0.000145 kg CO from combustion: 0.000122 kg Methane slip from combustion: 0.00000333 kg N2O from combustion: 0.00000318 kg Particulates from combustion, below 2.5 um: 0.000011 kg	no footprint	Reference product (grade, state): product is steam/mp-11bara (component H2O, grade saturated steam, 11 bar(a), phase gas, pressure 11.0, temperature 184.06); the routes state no grade (basis mole, component H2O, pressure 43.0, purity 1.0, temperature 400.0), no grade (basis mole, component H2O, pressure 46.0, purity 1.0, temperature 400.0), steam/mp-11bara (component H2O, grade saturated steam, 11 bar(a), phase gas, pressure 11.0, temperature 184.06) Functional unit: functional unit is 1 kg; the routes state 1 kWh, 1 kg System boundary: boundary is gate-to-gate: boiler, burner and fan, deaerator, feed pump; feedwater from outside, blowdown to wastewater treatment; most routes: gate-to-gate foreground of the plant Allocation: allocation is none (single product); most routes: shares Data quality (TfS DQR): states no data quality rating (TfS DQR)

How comparability is checked

Allocation: differs (same allocation method: exergy, none (single product), shares)
Background data (impacts): not applicable (same background data and boundary behind the impact numbers (only routes with a footprint))
System boundary: differs (same system boundary of the inventory (the dataset's boundary): gate-to-gate foreground of the plant, gate-to-gate: boiler, burner and fan, deaerator, feed pump; feedwater from outside, blowdown to wastewater treatment)
Data quality (TfS DQR): differs (data quality: every route states a TfS DQR, none more than 1 above the best)
Functional unit: differs (same functional unit (amount and unit of the reference product): 1 kWh, 1 kg)
Reference product (grade, state): differs (same reference product: registry grade and state: no grade (basis mole, component H2O, pressure 43.0, purity 1.0, temperature 400.0), no grade (basis mole, component H2O, pressure 46.0, purity 1.0, temperature 400.0), steam/mp-11bara (component H2O, grade saturated steam, 11 bar(a), phase gas, pressure 11.0, temperature 184.06))
System model: not stated by every route (same system model (docs/system-model.md): cutoff)

ISO 14044 requires a critical review (by a panel of interested parties, ISO/TS 14071) of a comparative assertion intended to be disclosed to the public. These routes are listed side by side for screening; a statement that one is better than another needs that review. None of these routes has had such a review.