Aerostat for electric power generation

Abstract

The exploitation of renewable energy sources is currently at the top of the agenda of many governments that are required to face the problem of the rising energy demand. In particular photovoltaics is considered one of the most promising technologies to meet the energy needs in the long term. However the effective exploitation of this source has always been hindered in many northern countries (like the UK) due to the weather conditions which are detrimental for the efficiency of photovoltaic generators.

As a possible solution to this problem, this research presents the preliminary concept evaluation of an innovative power generator based on photovoltaic and lighter than air technologies (Aerostat for Electric Power Generation – AEPG). The generator consists of a helium filled platform tethered to the ground that would be used to locate a photovoltaic array at high altitude, ideally above the cloud coverage, in order to reduce the negative effect of the atmosphere and optimize the power production. The power produced at high altitude would then be transmitted to the ground via the mooring tether.

First of all, the potential of this technology is evaluated in terms of the solar energy that can be collected at high altitude. The results obtained demonstrate that a generator located at an altitude between 6 km and 12 km could collect between 3.3 and 4.9 times the solar radiation that would fall on a ground based photovoltaic array. Furthermore the environmental conditions in which the system is due to operate are evaluated, employing standard atmospheric models and experimental wind speed datasets.

An overview of the main parameters involved in the design is then provided and general considerations are discussed in order to narrow the range of values these different parameters can take. A simplified mathematical model is introduced to assess the performance of the system in steady state conditions and a set of design parameters is chosen to define a baseline configuration for the concept design. Moreover, a transient 3D analysis of the whole system is performed in order to check if the dynamic behaviour can constitute a show stopper.

Finally the concept design of the AEPG is addressed and the most critical technical issues are identified. The location of the different subsystems is briefly discussed and a possible solution for the system layout is proposed. The study is completed with an initial sizing of the main components (structural in particular) in order to evaluate the different mass contributions and provide a preliminary assessment of the technical feasibility of the AEPG.

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