Analysis of Sodium–Water Reaction as heat source for district heating and cooling

Abstract

Finding new alternatives is a need to develop disruptive solutions that could be applied to the decarbonized, sustainable, circular systemic change for the energy system transition. In this case, a complete new approach, sodium as energy resource, is described. Traditionally, sodium has been considered a risky element even if it were proposed as coolant in many applications, as nuclear or solar thermal plants. Such applications have been concerned by the explosive reaction of alkali as Na with water. We analysed the alternative of profiting of such highly exothermic reaction for an energy use. Previously, we experimentally tested the utilization of sodium as propellant, as reported in Guerrero et al. (2019), what produced the correlation between the energy release and the sodium consumption in excess of water. We are now developing a boiler fuelled by sodium and water. Based on these previous and ongoing activities, this paper shows the proposal and the process analysis of a sodium–water boiler applied to heating and cooling networks,as one of the sectors to be decarbonized in the energy system. A tentative configuration for the design of such heater, and the heat exchangers to adapt heated water temperatures will be presented. We present the conceptual design of a 13.5 MW district heating plant for a ΔT=10°C heating water from 60 to 70 °C, consuming 1 kg/s Sodium, reaching an efficiency of 95%, comparable with existing boilers.