Power-to-Gas (PtG), E-Methane & Carbon Utilization Engineering
Sabatier CO2 Methanation H2 Demand, SNG & Heat Recovery Formula
Calculate Stoichiometric Green H2 Feed (kg/hr), Synthetic Natural Gas CH4 Output (kg/hr), Condensed Byproduct Water (kg/hr), and Exothermic Reactor Steam Duty (MWth).
Half of your expensive Green H2 hydrogen atoms exit Sabatier methanation as byproduct water H2O!
In Power-to-Gas (PtG) e-methane plants upgrading biogenic or captured CO2 into pipeline-grade Synthetic Natural Gas (SNG) over Nickel catalyst (CO2 + 4H2 -> CH4 + 2H2O, Delta_H = -165 MJ/kmol CO2 reacted), every 1 kmol of CO2 (44 kg) demands FOUR kmol of H2 (8 kg)—two kmol form CH4 (16 kg) and two kmol reduce CO2 oxygen atoms into 2 kmol of condensed water (36 kg)! Moreover, releasing 165 MJ per kmol of converted CO2 at 300–400°C generates high-pressure steam (MWth = (kmol_CO2_converted * 165) / 3,600) ideal for driving solid-oxide electrolysis or amine CO2 stripping!
Verify on an 11,000 kg/hr Captured-CO2 Methanation Train (250.0 kmol/hr CO2, B2) at CO2_Conversion = 0.96 (96.0% = 240.0 kmol/hr reacted, B3) and Reaction_Exotherm = 165.0 MJ/kmol (B4): Stoichiometric 4:1 Green H2 Feed is 250 * 8 = 2,000.00 kg/hr (E2), Produced SNG Methane CH4 hits 240 * 16 = 3,840.00 kg/hr (E3), Condensed Byproduct Water equals 240 * 36 = 8,640.00 kg/hr (E4), and Recovered Reactor Steam Heat equals (240 * 165) / 3,600 = 11.00 MWth (E5)!
| Sabatier Methanation KPI (11,000 kg/hr CO2, 96% Conv, 165 MJ/kmol) | Formula | Verified Output |
|---|---|---|
| Stoichiometric Green H2 (kg/hr) | (CO2_kg_hr / 44) * 4 * 2 | 2,000.00 kg/hr |
| Produced SNG CH4 Output (kg/hr) | (CO2_kg_hr / 44) * Conv * 16 | 3,840.00 kg/hr (3,200 @ 80% conv) |
| Byproduct Water Condensed (kg/hr) | (CO2_kg_hr / 44) * Conv * 36 | 8,640.00 kg/hr |
| Reactor Cooling Steam Heat (MWth) | ((CO2_kg_hr / 44) * Conv * dH_MJ) / 3600 | 11.00 MWth (9.17 @ 80% conv) |
Sabatier Synthetic Natural Gas (CH4) & Exothermic MWth Formula
Validate CO2_Feed_kg_hr > 0, CO2_Conversion in (0.10, 1.0], and Exotherm_MJ_kmol in [100, 220]!
=LET(c2_f, B2, cv_f, B3, dh_m, B4, IF(OR(c2_f <= 0, cv_f <= 0.1, cv_f > 1, dh_m < 100, dh_m > 220), "Invalid Sabatier Input", ROUND((c2_f / 44) * cv_f * 16, 2)))Single-Stage Equilibrium Pinch Conversion Drop Check (Set Conversion = 0.80)
Drop CO2_Conversion B3 from 0.96 (2-stage with inter-condensation) to 0.80 (single adiabatic bed): Produced CH4 E3 falls to 3,200.00 kg/hr and Recovered Steam Duty E5 drops to 9.17 MWth!
=IF(ISTEXT(E3), E3, ROUND(((B2 / 44) * B3 * B4) / 3600, 2))Try the example
Use the original values or change them to test your understanding.