Benefits of an integrated power and hydrogen offshore grid in a net‐zero North Sea energy system

•We develop a methodology to combine geographic information systems and energy system models via data clustering.•This novel methodology is applied to the north sea region.•The north sea offshore grid eases the integration of up to 338 GW of offshore wind.•A power-based offshore grid reduces the system costs by up to 8.7 bn € (4.1%).•A power-and-hydrogen offshore grid reduces the system costs by up to 14.9 bn € (7%).