Thermally Regenerative Ammonia Batteries for Waste-Heat Exploitation

Abstract

It is widely accepted that one of the most important issue to be faced by the scientific community is how to sustain the modern way of living and the related energy demand. While a long term target is the transition to a full-renewable energy system, a closer exigency is the optimization of the processes already existing. It has been calculated that about 370.41 TWh of potential energy is annually lost in Europe in the form of waste-heat from the industrial sector [1]. Waste heat comprises all the thermal energy with a temperature below 130 °C [2] (or 300 °C [1]), that hardly can find a useful application with the state of the art industrial technologies. Indeed, electrochemical technologies are nowadays under investigation for the potentiality they own to harvest, at least, part of this energy [2]. Among the others, Thermally Regenerative Ammonia Batteries (TRAB) were reported to have very high current density and simple operation [3], but most of the work accomplished up to now was devoted to the optimization of the generation phase in conventional divided reactors. In this work, our efforts for the optimization of the regeneration phase are reported, along with a detailed exposure of the apparatus adopted. In addition, the use of an undivided continuous-flow, microfluidic reactor is proposed to sustain higher current densities with reduced investment cost. The effect of some relevant operative parameters on the maximum current density that can be gained in such a microfluidic device is also discussed.