Large-scale hydrogen storage has been a formidable challenge and a major obstacle in developing green hydrogen infrastructure. It is a key enabler for production of green ammonia, to reconcile intermittent green hydrogen sources with steady Haber-Bosch processes. Vallourec and NEXTCHEM have studied several green ammonia production projects to establish the best CAPEX and OPEX for hydrogen storage projects. The case studies demonstrate that integrating small-scale green ammonia technology not only offers a safe, compact, and flexible solution for hydrogen storage but also enables a reduction in overall storage and ammonia synthesis costs by up to 15%. The presentation will discuss main findings of these case studies, in terms of design, costs, plant lay-out, etc., and lessons learnt for future green H2 and green ammonia projects.