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of electricity generated versus heat generated – can vary. While PEMFCs are typically 50% efficient, generating about a watt of heat for every watt of power, mSOFCs can achieve different efficiencies depending on the electrical and heat demands of the system. Also, the reuse of heat, for maintaining the internal working environment or other purposes, should be factored in for a clear understanding of what ‘efficiency’ means. If the heat were not recycled, and the 700-750 C internal temperature were maintained through a constant energy supply, the mSOFC would be 30-50% efficient. However, since some of the heat is recycled (albeit with some escaping via the exhaust), the mSOFC’s energy efficiency is estimated at 65%, with capacity to improve. “In principle, from 100 W of power you can get around 300 W of recovered heat,” Dr Kendall says. “We actually want that, because it helps with our system design and operation – with better efficiency it’s better environmentally, although our customers have typically focused less on efficiency and more on weight optimisation. “That real efficiency could go as high as 95% if you recycle the heat in other ways, such as thermal management and de-icing in unmanned vehicles working in freezing conditions.” Adelan is also in the process of designing a new ECU for its fuel cell modules with Aston University in Birmingham, which will be customisable to match the different scales of modules the company can produce. As aviation regulators gain familiarity with the range of fuel cell systems now available for UAVs, Dr Kendall anticipates a path towards certification that will eventually enable development of Adelan’s technology to a standard that will garner further recognition and interest in the viability of mSOFCs for unmanned vehicles. The company is working on a new ECU, developed from a blank sheet to work according to the mSOFC’s chemical properties, fuel consumption and power output