*2.1. Supply Technologies under Consideration*

The electrification of aircraft comes with immense stress to the airport's electrical system due to the vastly increased power demand for charging airplanes. In addition, a mid-to-long-term infrastructure should aim to improve the airports' entire energy system, including information technology (IT) and control systems, lighting, and general-use low voltage supply. Furthermore, building a hydrogen infrastructure with a new generation of tanks, pipelines, and supply possibilities to refuel the aircraft is also necessary. Instead of overhauling the existing system, the short-term (2025–2035) analysis will focus on an electrical grid whose sole purpose is to charge aircraft on the airfield. The medium-term (2035–2045) time perspective includes more fast-charging stations and the possibility of including a hydrogen infrastructure. As assessed for the regional airport, the needed hydrogen infrastructure onsite will provide only storage on wheels and tanks. The hydrogen production will be off-site in a nearby harbour. The components currently limiting the airport infrastructure and required to be installed and/or revised are (i) connection to the main grid, (ii) local photovoltaic supply, (iii) charger for aircraft, (iv) charger for airfield support vehicles, (v) local battery storage and (vi) local hydrogen storage.

Even with a local supply of electricity from the airside solar park and storage, the grid feed-in for an infrastructure capable of charging multiple aircraft and support vehicles will need to be connected to the medium-voltage grid (6 kV to 60 kV) due to the high-power demand. The distribution network on the airport premises should then be realised on a low-voltage level (or according to the low voltage directive 2014/35/EU) due to safety reasons. The AC (analog current)-concept utilises a common AC bus for the distribution system. It is a standard electrical installation, as it is common in most of the world [11].

Photovoltaic power generation, fuel cell technology, stationary battery storage, and mobile batteries in aircraft and escort vehicles are DC (direct current)-based by nature. A second concept links all components to a low-voltage DC grid (<1500 V). This DC grid must be rebuilt entirely at an airport [11]. This possibility is mentioned in this article for completeness but is not considered in more detail in the scenarios, as the RTHA airport operates with an AC-based grid. Sections 2.1.1 and 2.1.2 briefly describe the type of supply voltage and the basic connection of a Fast-Charging-Station to the airport grid.
