An Airship Design Methodology Based on Available Solar Energy in Low Stratosphere

Abstract

The actual applicative research concerning airships and their use as HAP (High Altitude Platforms for telecommunications and military use) presents new applicative hypothesis of these systems, also concerning energetic high quote production. Authors present the energetic balance of a high quote photovoltaic platform with capability of static hovering realized by electric powered propellers. This is the first step trough the design of the P. S. I. C. H. E. (Photovoltaic Space Island for Conversion of Hydrogen as Energy vector) airship concept: a stratospheric airship which could be considered a platform for hydrogen and oxygen production by photovoltaic. It investigates the behaviour of a similar platform operating at altitudes between 10 and 20 km, positioned at 45° latitude north [1, 2]. This paper analyses the design process for a High Altitude Platform based on photovoltaic energy caption, but the process could be generalized in order to be applied to any airship project. It is considers airship shapes equipped with large PV array that covers energy request during the day. Surplus in power supplies electrolyser equipments for hydrogen and oxygen production from water, which could be captured by atmospheric humidity or brought by an auxiliary airship. Hydrogen and Oxygen are compressed and stored in gas cylinders. With insufficient solar irradiance, with severe wind conditions and during the night, a fuel cell system fed by hydrogen and oxygen tanks supplies power requirements. The Standard Atmosphere Model is used to evaluate PV performance at various operative altitudes. A propulsion system with electric motors grants airship manoeuvrability and hovering. Energy balance of PV-hydrogen energy supply system has been analyzed for three airship shapes with equal volume with concern of overabundant hydrogen and oxygen production. Total weight and payload are calculated in relation to altitude. Storage tanks dimensions and products ground transportation frequency has been estimated. Hydrogen annual production for PV square meter has been evaluated in relation to ground production at the same latitude.