This paper will discuss a powerful, rigorous and unique solution that can model the end to end hydrogen economy, or any subset, easily, rigorously and flexibly. This system can evaluate the impact of alternative capital investment in renewable power capacity, electricity storage (batteries and other), hydrogen production options (such as electrolysis), carrier fluids (such as ammonia or cryogenic hydrogen), storage, transport, and end use (power generation, fuel cells, chemicals such as fertilizers). We will explain the basis and capabilities of this modeling system (Aspen Fidelis) for the hydrogen economy but also for other areas such as CCUS, reduced carbon intensity LNG, and biofeedstocks. USE CASES: This digital approach has been applied on several major hydrogen projects, and this paper will explain several use cases, such as (a) evaluation of multiple electrolysis technologies for selection of the “winning” technology based on demonstration scale operation at Doosan, (b) sizing of downstream process units to optimize sizing and CAPEX of process assets that complement hydrogen production at Air Products, (c) evaluation of a multi-country hydrogen economy value chain – at a customer site.