Energy Storage By Reversible Chemical Reaction - Heat Exchange and Environmental Impact Issues

Energy saving, pollution reduction and energy storage are intrinsically interrelated and this cluster of issues constantly grows in importance. One way of solving the presented challenges is to considerably improve the capacity and reduce the cost of energy storage. Reversible chemical reactions are one of the options for storing thermal energy and considerable research effect has been made in this topic.

Some recent solutions and achievements are overviewed. One of the potentially successful applications for storing the solar heat for family houses was presented by EC Project ENERGIE NNE5-2000-00385 ‘Improvement of the efficiency of solar thermal systems by integration of a thermo-chemical storage processes - SOLARSTORE’ by a research team including ADAI (Portugal), CLIPSOL and CNRS CREED (France), DALKIA (Spain) and University of Manchester (UK). Their experience pointed out that it is rather important to take into consideration the environmental impacts caused by production of thousands of thermal storage systems. The LCA methodology needs to be extended to analyse the total environmental impacts caused by the need to produce, reprocess or dispose thousands of thermo-chemical storage systems.

Some other issues with thermal energy storage applied to store low potential heat and heat generated by the renewable sources have been assessed as well. One of them is a need for much smaller minimum temperature approach than for the high temperature sources produced mostly by fossil fuels. When we apply thermal storage the need for the heat exchange has been minimally doubled and this can be for low potential (Low temperature) heat a problem. Advanced types of heat exchangers are needed allowing smaller temperature approach at still acceptable sizes and prices for enlarged heat transfer area. The environmental footprints for producing, maintaining (including the fouling) and disposing those heat exchangers should be considered as well.

The presentation is summarising those issues related and raised by implementation of the heat storage, exploiting the author’s industrial experience, and suggesting the direction for the future research.