Lithium-Sulfur Batteries

12 Case Study

High‐Altitude, Long‐Endurance Unmanned Aerial Vehicles (HALE UAVs) – A Perfect First Application for Lithium–Sulfur Batteries

Paul Brooks

Prismatic Ltd, Cody Technology Park, Farnborough, Hants, GU14 0LX, UK

12.1 Introduction

Flying forever using only the power of the sun – this is the vision for solar‐powered, high‐altitude, long‐endurance, unmanned aerial vehicles (HALE UAVs). It is a vision that has been around since the early 1980s and, despite the attention of some of the great names in aerospace and innovation, remains as yet an unfulfilled promise.

The concept is simple. Fly using electric motors and propellers, with photovoltaic (solar) cells providing the power to fly during the day and to charge batteries to maintain flight overnight. There are two variants to the concept – an aeroplane that flies using aerodynamic lift and an airship (lighter than air, LTA) that uses a lifting gas (usually helium) to maintain altitude and electric propulsion to maintain location. In both cases, the need for a continuous source of power results in the use of photovoltaic (PV) solar cells and regenerative electric energy storage. This case study takes the highest level interest and requirements in such systems – focusing on aircraft that have been more successful to date – and considering the technical and business drivers on the systems shows how regenerative electrical storage, specifically high specific capacity batteries, is both the critical element in ...