## 3 Potential of Water Resources in Magallanes Region  
The Magallanes region and Chilean Antarctica, despite its relative abundance of water resources, faces important restrictions for the use of land water in the production of green hydrogen, derived from legal, environmental, climatic, and social factors. These limitations pose significant challenges for the development of great GH2 projects that exclusively depend on fresh water sources [23]. First, the Chilean legal framework establishes rigorous conditions for the appropriation of water resources. The current water code, although modified in 2022, maintains a system of use rights that, in Magallanes, is already partially assigned for other priority uses. Obtaining new water decrees for industrial green hydrogen projects can be complex, especially in areas close to populated centers such as Punta Arenas or Puerto Natales, where the resource is mainly intended for human consumption and traditional productive activities [22]. From the environmental point of view, water extraction for electrolysis faces important barriers. The region houses fragile ecosystems, such as Patagonia wetlands and ice fields, protected by various regulations. The Glacier Protection Law (Law 21.100) especially restricts any intervention in areas close to these natural freshwater reservoirs. In addition, environmental impact studies for large-scale projects usually face particularly rigorous scrutiny, considering the ecological and tourist value of many bodies of water in region [25]. The climatic characteristics of Magallanes add another layer of complexity. The marked seasonality in water availability, with maximum flows in summer for thaw and minimums in winter, would require expensive storage systems to guarantee a continuous supply. Additionally, low winter temperatures can freeze superficial water courses, limiting their accessibility during that part of the year. These variations would force specialized infrastructure to design and increase operating costs [26]. The competition for water resources with other economic sectors represents another important limitation. Tourism, a key activity in the region, directly depends on the conservation of the landscape and the bodies of water in places such as the Torres del Paine National Park. Simultaneously, sheep livestock, although less intensive in water use than other agricultural activities, remains an economic pillar that requires a supply of water. This multifunctionality of the water resource generates potential tensions that must be considered in any green hydrogen project [25]. Finally, from a logistics and economic perspective, the use of land water has comparative disadvantages against the desalination of seawater. The need to transport water from distant sources to optimal places for wind generation (frequently located in coastal areas) would significantly increase costs. In addition, the infrastructure required for sweet water treatment and distribution would have to adapt to the extreme climatic conditions of the region, increasing the necessary initial investment [26]. The Magallanes region is positioned as one of the largest potential territories to produce green hydrogen (GH2) globally, thanks to its exceptional windings and the strategic availability of seawater, which can be transformed in a key input through desalination processes against the use of fresh water (Table 1). Magallanes has an extensive coast bathed by the Pacific Ocean and the Magallanes Strait, which guarantees an unlimited supply of seawater for GH2 production [23]. Some of the key benefits of the use of desalinated water are the following:  
* Abundant resources: unlike freshwater, seawater does not compete with agricultural, human, or tourist uses. * Strategic location: Desalination plants can be installed near wind farms (such as those projected in Tierra del Fuego or San Gregorio), minimizing the logistics costs. * Sustainability: If residual brine is properly managed, environmental impact can be controlled by dilution or re-utilization technologies.