Thermochemical seasonal solar energy storage for building applications (SeasonalStorage)

A project trialling the use of reversible chemical reactions to store energy.

Lead Organisation

Environmental Process Systems






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Summary: impacts and findings

This project trialled the practical use of thermochemical energy storage. It showed that systems using reversible chemical reactions can be used to store energy over long periods of time. This could potentially add flexible storage to smart local energy systems, helping to bridge the gap between energy generation and demand in community buildings, and reducing CO2 emissions.

Project aims and approach

This project aimed to exploit the principle of thermochemical energy storage. This uses a reversible chemical reaction. For example, heat is used to separate the components of a chemical compound; the components are stored separately at room temperature and, when recombined later, produce heat.

In this way, energy from renewable sources can be captured during times of low demand, stored for long periods – such as from one season to the next – and then used when demand is high.

The disadvantages of using hot water cylinders as storage are eliminated by SeasonalStorage technology. The system requires no thermal insulation in order to store heat for long periods of time and offers heat on demand via a chemical reaction without any harmful gases.

The SeasonalStorage project designed, developed and installed a prototype solar-powered thermochemical energy storage system. The technology combines solar photovoltaic cells and novel hollow fibre heat exchangers, storage using novel environmentally-friendly thermochemical materials including vermiculite, and a smart controller. The test system was installed in a real demonstration building at Nottingham University.


  • Environmental Process Systems
  • Arkaya Energy
  • P.A.K. Engineering
  • University of Nottingham


July 2020 to June 2022 

Achievements and barriers

Studies based on the test rig, carried out by Nottingham University, showed that use of the thermochemical heat storage system for domestic space heating is feasible. The storage solution can be run stand-alone or as a key component integrated into existing local energy systems.


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