The application of fuel cells in our future energy system depends on a cost-efficient production and supply of hydrogen (H₂) and carbon monoxide (CO). The process cycle iron oxide/iron/hydrogen offers a simple possibility to store the energy of synthesis gases in the form of sponge iron and at the same time to reform and condition these synthesis gases. As `product' of this energy storage system one receives pure hydrogen. The `Sponge Iron Reaction' (SIR) process offers some advantages against conventional gas cleaning and conversion processes: (i) low-cost hydrogen by using cheap sponge iron materials; (ii) high-quality hydrogen from low-BTU gases by a two-step operation; (iii) high efficiency compared with competitive technologies and (iv) system versatility and ease of siting. Commercially available iron ore pellets (hematite Fe₂O₃) and self-produced pellets are used as contact mass.