Azelio’s thermal storage coupled with water treatment system: a techno-economic analysis

Abstract

This paper presents the analysis and results developed during a five months internship with the Swedish company Azelio. The objective of this thesis is to assess the possibility of running a water treatment system with low-grade waste heat produced during the operation of Azelio’s thermal storage. The paper presents an overview of water treatment solutions and thermally driven waste heat treatments. This allowed the selection of a fitting water treatment technology that could be coupled with the thermal storage. To fulfill the objective, different techno-economic models have been developed to assess the cost of water and electricity production for a variety of setups. Desalination was selected to be the water treatment to investigate, both for the presence of prolific literature on the economies and technologies of desalination, and its growing market trend. The techno-economic models were developed and sized to satisfy a demand for either baseload electricity or clean water annual production. The desalination technologies adopted in the case analysis are membrane distillation and reverse osmosis. Each case was assessed through economic and performance indicators: Levelized cost of electricity and water production, land required, and carbon dioxide emission reduction with respect to fossil-based generation. The economic resilience of the models has been tested with sensitivity analysis to show how the indicators vary with different technology costs and discount rates. The analysis led to the conclusion that for power baseload demand the capital investment to add a desalination system is not paid back by water sales. For clean water demand, the long-duration storage has remarkable advantages in operating a reverse osmosis plant when compared to solar generation only. In case of a demand for both clean water and electricity, especially in decentralized locations, the integration of membrane distillation and solar collector proved to have potential for future applications.