(93c) Thermal Energy Storage (TES) with Silica Gel Regenerated at Low Temperature

The energy system around the world is facing technology transformation. The deployment of renewable energy generation and the development of new clean technologies offer the opportunities to diversify energy supply, improve energy independence and reduce carbon dioxide (CO₂) emission [1][2]. Although it is environmentally beneficial to use renewable energy in the electricity production, heating purpose and transportation, one of the main difficulties faced by the energy industry is the absence of economic and reliable energy storage solutions [3]. Thermal energy storage (TES) provides a solution to store energy generated from different types of energy sources (traditional or renewable) and correct for the mismatch between the energy supply and demand. TES through water vapor adsorption process has attracted increasing interest for its thermal applications such as space heating and cooling.

Various kind of materials have been investigated in search of adsorbents with high energy density for TES. Most of the energy density data reported were either theoretical data or experimental results obtained at high material regeneration/desorption temperature (e.g. 135 – 250⁰C) [4]. However, experimental energy density of the adsorbent varies if the design and the construction material of the system and/or the operating conditions change. Therefore, the experimental energy density could be much lower than the theoretical energy density. Moreover, for most of the residential renewable energy heating sources, such as solar water heating system [5] or building-integrated photovoltaic/thermal (BIPV/T) systems [6], the temperature of dry air that the system could provide for material regeneration is less than 80⁰C.

In our previous study [7], silica gel has been identified as a promising adsorbent candidate for thermal energy storage applications. In this study, a commercial silica gel material was used to examine the effects of relative humidity (RH) on the material behaviour and its experimental energy density at low regeneration temperature (50 – 80⁰C). The experimental results showed that an energy density of 120 kWh/m³ could be obtained under cyclic operating conditions with low RH and low regeneration temperature.

References

[1] B. Moreno and A. J. López, “The effect of renewable energy on employment. The case of Asturias (Spain),” Renew. Sustain. Energy Rev., vol. 12, no. 3, pp. 732–751, 2008.

[2] P. del Rio and M. Burguillo, “Assessing the impact of renewable energy deployment on local sustainability: Towards a theoretical framework,” Renew. Sustain. Energy Rev., vol. 12, no. 5, pp. 1325–1344, 2008.

[3] U. Lehr, J. Nitsch, M. Kratzat, C. Lutz, and D. Edler, “Renewable energy and employment in Germany,” Energy Policy, vol. 36, no. 1, pp. 108–117, 2008.

[4] F. Fischer, E. Lävemann, A. Krönauer, and A. Hauer, “Open adsorption systems for thermal energy storage applications,” in BIOWKK Workshop Dortmund 2012, 2012.

[5] R. Shukla, K. Sumathy, P. Erickson, and J. Gong, “Recent advances in the solar water heating systems: A review,” Renew. Sustain. Energy Rev., vol. 19, pp. 173–190, 2013.

[6] T. Yang and A. K. Athienitis, “A review of research and developments of building-integrated photovoltaic/thermal (BIPV/T) systems,” Renew. Sustain. Energy Rev., vol. 66, pp. 886–912, 2016.

[7] Y. Hua, A. Godin, T. Alenko, B. Ugura, and F. H. Tezel, “Adsorbent Screening for Thermal Energy Storage Application,” in 14th INTERNATIONAL CONFERENCE ON ENERGY STORAGE, 2018.