Environmental and Economical Requirements for a Sustainable Zn/air battery

Resumen

The transition towards an energy system with high penetration of renewable energy demands the use of energy storage. Batteries will be part of the solution, specially for a massive penetration of electric transport which will require small or medium batteries which are sustainable from an environmental and aneconomical point of view. Lead-based, alkaline or lithium-ion based batteries are already in the market. Innovative technologies such as Li/air, with an energy density theoretically ten times higher, are being investigated; the environmental impact for its production could be reduced by an amount between 4 and 9 times when compared with conventional Li-ion and by recycling, up to 30% of production related environmental impact could potentially be avoided [1]. Nevertheless, it is difficult to compare the environmental impact of well stablished and emerging technologies since their use-phase (specially cycling and lifetime) is very different and it makes difficult to propose a functional unit for a comparative Life Cycle Assessment (LCA). We propose a methodology to evaluate the sustainability of different energy storage systems in which conventional batteries are compared with innovative approaches such as metal/air batteries, with special focus on a comparison between Li/Air and Zn/Air batteries [2]. The result of the evaluation depends mainly on the processing routes for battery fabrication, the efficiency and cyclability of the battery during the operational phase and the decommission of the battery including recycling and/or land- filling at the end of life. Using the same functional unit for the different technologies (energy stored averaged throughout battery life time), the requirements for the Zn/air battery in order to become the solution with lower environmental impacts are provided taking into consideration that electrolyte formulation, cell design and separators affects the properties of the battery. Similarly, a calculation of the levelized cost of energy storing capacity of the battery (averaged throughout battery life time) provides an economical comparison of different technologies and poses clear requirements for any new technology in order to penetrate the market.