Process for producing a synthesis gas

A process for manufacturing a hydrogen-containing synthesis gas from a natural gas feedstock including a stage of converting said natural gas feedstock into a raw product gas and purifying said raw product gas, said process includes providing heat input by combustion of a fuel, wherein said process includes producing a gaseous fuel and combusting said gaseous fuel to provide at least part of said heat input to the stage of converting, said process for producing said gaseous fuel comprising:

• a) gasifying a solid or liquid carbonaceous feedstock into a first gaseous product;
• and
• b) treating said first gaseous product to obtain said gaseous fuel which is not used as a process gas, said treating including at least one of:
• b1) removing carbon dioxide with a purity of at least 90% molar;
• or
• b2) methanation;
• wherein said gaseous fuel has an upper Wobbe Index of at least 14 MJ/Nm3.