At 3 kW the cell runs at 53.5% efficiency and consumes 0.168 kg of hydrogen per hour (1.87 Nm³/h). Each kWh costs 0.67 € in fuel versus about 0.71 € from a diesel generator. Your 12.6 kg of stored hydrogen lasts 3.1 days at this load.
Hydrogen consumption
0.168kg/h
1.87 Nm³/h · 56 g per kWh
Efficiency at this load
53.5%
PEMFC · rated 50%
Runtime from storage
3.1days
12.6 kg stored
Electrical output
3kW
8,760 kWh/yr
Heat produced
2.61kW
1.56 kW recovered at 60–80 °C
Total CHP efficiency
81.4%
electricity + recovered heat
Water produced
1.5L/h
8.94 kg water per kg H₂
Fuel cost per kWh
0.673€/kWh
0.631 after heat credit
Fuel cost per year
€5,896
2,920 h/yr
Fuel per year
491kg H₂
Diesel generator equivalent
€6,214
1.33 L/h · 10,408 kg CO₂/yr (fuel cell 0)
Fuel-cell types at a glance
| Type | Electrical efficiency (LHV) | Operating / heat temperature | Fuel | Min. load | Typical use |
|---|---|---|---|---|---|
| PEMFC (low-temperature PEM) ◀ | ~50% | 60–80 °C | H₂ | 5% | vehicles, backup, portable |
| HT-PEM (high-temperature PEM) | ~45% | 120–180 °C | H₂, natural gas / biogas | 10% | CHP, methanol reformers |
| SOFC (solid oxide) | ~58% | 600–900 °C stack, ~200 °C exhaust | H₂, natural gas / biogas | 30% | stationary CHP, data centres |
| PAFC (phosphoric acid) | ~42% | 150–200 °C | H₂, natural gas / biogas | 30% | commercial CHP |
| MCFC (molten carbonate) | ~47% | 600–700 °C | natural gas / biogas | 40% | utility-scale CHP |
| AFC (alkaline) | ~55% | 60–90 °C | H₂ | 10% | space, niche stationary |
- Consumption = electrical power ÷ (efficiency × 33.33 kWh/kg). Efficiencies are system values on the lower heating value; datasheets sometimes quote stack efficiency, which is higher.
- Part-load curve is generic: low-temperature PEM gains efficiency at part load, high-temperature cells much less, and all lose some to balance-of-plant at very low loads. Stack ageing raises consumption by a few percent over life.
- Cylinder contents are approximate usable mass at 15 °C; real gas behaviour means 700 bar holds only ~2.5× the hydrogen of 200 bar, not 3.5×.