Steam reforming an endothermic reaction

The steam reforming of natural gas to give "synthesis gas", an endothemic process

CH₄(g) + H₂O(g) CO(g) + 3H₂(g) Δ_rH = +206 kJ mol⁻¹

At 25 ^oC, K_p = 8.6 × 10⁻²⁶; the equilibrium system is far to the left.

But at 850 ^oC K_p = 50.

Thus this reaction can be made to go by heating to a high temperature.
Since the reaction is endothermic, constant heat energy is necessary to keep the reaction going.