After years of growing concern over climate change, energy companies are striving to develop viable technologies using their expertise to reduce their carbon footprint. Carbon Capture and Storage (CCS) technology has strategic interest for two reasons: firstly, it is one of the pillars of a net zero strategy thanks to the capability of directly reducing part of the emissions related to the business; secondly, CCS is emerging as a new market to provide decarbonization solutions to the industry such as the hard-to-abate sectors. Depleted reservoirs at the end of their productive life offer convenient opportunities to develop CCS hubs. Offshore CCS projects are nowadays largely limited to shallow water, but deep water CCS developments are likely to play a crucial role in the next future as the storage demand grows. The aim of this presentation is to show specific requirements and related architectures for a subsea system able to inject carbon dioxide in depleted reservoirs, with interest in new technologies addressing cost-efficient solutions. The design of a subsea injection system is affected by a large number of parameters. Among them are the step-out distance from the host facility, the water depth of the injectors, the thermodynamic conditions and the flow rate of the carbon dioxide, reservoir conditions, and the wellhead locations on the seabed. This presentation isolates all these parameters and discusses their impact in terms of CO2 phase behaviour (gas, dense or liquid) and operability of the injection (single or multi-phase). Sensitivities of these parameters were performed and implications in the overall development are presented. Different sets of parameters were then selected to build up some realistic case studies, leading to different suitable subsea architectures. The proposed subsea architectures are underpinned by a set of emerging concepts and technologies, as well as state-of-the-art products. Among them, the subsea electrification – together with the DC/FO cable – can remove the need for hydraulic-chemical distribution provided that the injection parameters are such that no inhibitor is required. Furthermore, downhole chokes could allow for the regulation of flow downhole, thus preserving the subsea injection equipment from issues such as low temperature due to CO2 phases changes. This presentation shows how new technologies can provide effective and cost-efficient solutions. The proposed architectures are compared to a baseline gas production development, highlighting potential simplifications of the system and cost saving areas.