In this thesis, we consider investment optimization for airport infrastructure which is required charge and refuel electric and hydrogen powered aircraft using battery and hydrogen canister swaps respectively. The task at hand is to determine the most cost-effective infrastructure, consisting of spare batteries, and battery chargers for electric aircraft, and spare hydrogen canisters and fueling points for hydrogen aircraft. Previously developed models are expanded upon in this study by introducing the possibility of slot allocation, where flights that are not yet in possession of landing and take-off rights are assigned to them in such a way that requires the smallest extra infrastructure to be acquired. We derive several (mixed) integer linear programming formulations to solve this problem and develop heuristics which are able to approximate the optimal solution using only open-source resources. These are expanded upon by the introduction of instances where more than one battery type is allowed, electricity pricing becomes dependent on the time-of-use, and storage of electricity at the airport is allowed such that the peak demand can be as low as possible. Finally, we incorporate a distinction between the long-, medium-, and short-term decisions which have to be made by the airport operator into the model analysis. This allows the user to determine the most cost-effective infrastructure combination which can meet a required level of service. When testing these methods, we found that exact solutions can be found within reasonable time for cases with up to 200 batteries. Furthermore, a first-in-first-out policy heuristic has shown to be capable of generating promising results while being applicable to larger instances. The models have been illustrated in a case study at the airports Schiphol (Amsterdam) and Zestienhoven (Rotterdam - The Hague), where they have proven to be able to solve all daily instances to optimality.