Advancements of a piston engine and electrochemical combined hybrid system for unmanned aerial systems

Thomas S. Welles, Jeongmin Ahn

Research output: Chapter in Book/Entry/PoemConference contribution

1 Scopus citations


This work investigates the integration of solid oxide fuel cells (SOFCs) and a small methanol/nitromethane fueled piston engine as a prospective hybrid powertrain for small unmanned aerial systems (UASs). The increased chemical energy density of a liquid fuel when compared to traditional batteries, along with ease of storage, accessibility, and refuel time make the use of a liquid fuel powered UAS preferable when compared to battery only power UAS'. Currently small UAS' of increasing interest as a research area, as they have a wide application to a variety of fields. UAS' are currently being used for precision agricultural crop management and water resource visual inspection. UAS' are a cost effective avenue to survey water resources and track water runoff that is contaminating water resources. UAS' can be easily automated and fitted with sensors and cameras capable of providing actionable feedback to the user. The use of UAS' for land management and survey is expected to continue to expand. However, nearly all UAS' are powered by a typical lithium polymer battery pack, giving an average endurance of approximately twenty minutes. This is acceptable to most hobbyists and for short filming duration; however, it limits UAS' to only being able to be operated in close proximity to the user. Current power plants for UAS' are not suited for long duration missions, such as the survey of water resources. Therefore, the development of a hybrid power plant is crucial for UAS' to be utilized to their full potential as a survey tool. This work introduces a small internal combustion engine to act as a partial oxidation fuel reformer, producing high temperature exhaust and syngas. The exhaust of this engine is then analyzed as a fuel source for tubular SOFC's. The SOFC is integrated into the exhaust of a 3.3 cm3 nitromethane fueled two-stroke engine, achieving a maximum power of 680 mW/cm2. A theoretical comparison of flight time indicates that the modular hybrid system could increase a typical small UAS' flight time beyond 1 hour. The system is capable of achieving a significantly higher energy density than traditional lithium polymer batteries.

Original languageEnglish (US)
Title of host publicationASME 2020 Power Conference, POWER 2020, collocated with the 2020 International Conference on Nuclear Engineering
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791883747
StatePublished - 2020
Event2019 Canadian Society for Civil Engineering Annual Conference, CSCE 2019 - Laval, Canada
Duration: Jun 12 2019Jun 15 2019

Publication series

NameAmerican Society of Mechanical Engineers, Power Division (Publication) POWER


Conference2019 Canadian Society for Civil Engineering Annual Conference, CSCE 2019


  • Electrochemical hybrid system
  • Hybrid powertrain
  • Solid oxide fuel cells (SOFCs)
  • Unmanned aerial systems (UASs)

ASJC Scopus subject areas

  • Mechanical Engineering
  • Energy Engineering and Power Technology


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