The current state of the transport sector does not adhere to the stringent legislation and expectations set by governments and communities worldwide. The burning of fossil fuels within the internal combustion engines of lightweight motor vehicles involves the depletion of a non-renewable resource and is environmentally damaging. In trying to meet and exceed expectations, governments and corporates are continuously investing in research and development to find innovative ways of producing 'clean' energy in the transport sector. Recent efforts have been made to find a substitute fuel that is both economically feasible and environmentally benign. Solar power appears to be an attractive potential substitute due to its non-existent emissions during use and the abundance of solar energy available. On the other hand, solar powered vehicles cannot be commercialized due to the high cost of batteries, low energy storage capacities, poor practicality, and various design challenges that are encountered. In addition to this, hydrogen as a fuel to be used in proton exchange membrane fuel cells (PEMFCs) has made a considerable impact on the 'clean' fuel industry; although hydrogen is the most abundant element on earth and the only by-products produced are energy and water, the application of this technology is hindered by the pollution resulting from the hydrogen extraction process, and various cost, infrastructure and safety limitations. There is however an electrochemical reaction available to us that delivers sufficient electrical energy to move a weighted-vehicle, namely the zinc-air battery. It is simple, cost effective, safe to store and transport. With a wide array of positive characteristics such as economic and environmental efficiency, resource abundance, high energy density, extended storage lifetime and general utilization safety, zinc-air batteries appear to be a feasible candidate to solve the fuel crisis that the world is currently facing. It does come with several limitations that are preventing its commercial production and application but appears to be the shortest path to overcoming the dilemma we are currently facing. This paper briefly investigates and compares the costs involved with the all three power sources as well as the efficiency limits achievable by the zinc-air and hydrogen cells. (C) 2019 The Authors. Published by Elsevier B.V.
