|To protect the Netherlands for the effects of climate change, the Netherlands agreed to lower their CO2 emissions by 49% in 2030 relative to 1990. Tata Steel IJmuiden (TSIJ) plays a crucial role in this reduction target since it emits 7% of the CO2 emissions in the Netherlands. Deep decarbonization of TSIJ is therefore key to meet the CO2 reduction goal. Using a Mixed Integer Linear Programming (MILP) based framework, this research quantifies the CO2 reduction by changing the current energy system towards a minimal CO2 emission design. The energy system is currently designed in a low-cost manner, which is not the most optimal regarding CO2 emissions. The results showed that the potential of decarbonizing the energy system without process changes is limited. Therefore, the effects of three process changes, namely electrification of heat, utilization of an Electric Arc Furnace (EAF), and utilization of the Hisarna process, are investigated. The process changes were selected to represent the short-term and mid-term plans of TSIJ and are reflected in a change of demand and emission profiles. The results showed that the decarbonization potential of electrification of heat is limited, while the CO2 reduction potential of utilization of the EAF and Hisarna is approximately 30% each. This is still not enough to reach the CO2 reduction goal. To reach the CO2 reduction goal, both the utilization of CCS and the implementation of renewable electricity are needed. The potential of renewables on the TSIJ is limited due to a lack of space. Hence the supply of lower carbon electricity relies on implementing more renewables for electricity generation on the national grid.