## 4 Conclusions and Future Prospects  
Cold-to-power systems are still rare in the energy sector, but reveal promising opportunities to make the energy system more flexible and integrative of renewables. In spite of their environmental friendliness, at today's technology level, standalone cryogenic energy storage systems (and specifically LAES) could still hardly compete with established energy storage principles as regards RTE. Thus, LAES needs to find niche areas in order to become a more viable and economical option by means of appropriate hybridisation and embedding into highly energy-intensive technologies and economic sectors.  
\begin{table}
\begin{tabular}{c c c} \hline
**Scenario** & **A** & **B** \\ \hline Power input, kWh & 110,871 & 110,871 \\ \hline Power output, kWh & 52,407 & 38,295 \\ \hline RTE of power generation only, \% & 47.30 & 34.50 \\ \hline Heating load, kW & N/A & 2142 \\ \hline Useful heating output, kWh & N/A & 19,278 \\ \hline Refrigeration load, kW & N/A & 456 \\ \hline Useful refrigeration output, kWh & N/A & 4104 \\ \hline Total useful energy output (heat, cold and power), kWh & N/A & 61,677 \\ \hline RTE of tri-generation, \% & N/A & 55.63 \\ \hline \end{tabular}
\end{table}
Table 3: Round-trip efficiencies of the LAES plant for scenarios A and B.  
Multipurpose renewable-powered LAES systems, employed for the poly-generation of heating, refrigeration and electricity, prevail in terms of functionality, flexibility and efficiency over the standalone systems producing electricity only. The present contribution proved this circumstance by exploring a case study of coupling LAES with a typical food factory producing frozen French fries. A tri-generation LAES configuration was proposed to produce power (for on-site or in-grid use) and to supply the factory with steam and cold air. By recovering the excess heat and cold, a tri-generation RTE of 55.63% could be reached, which exceeds 1.2 times the RTE of a typical standalone baseline system. A 9 h night charging cycle was assumed, which implies that wind power sources are a good candidate to feed renewable energy into the suggested LAES system.  
The elaborated case study is the first of its kind, which addresses the potential synergy between LAES and food industry in a quantitative manner. Similar case studies might be found out in the food chains for meat, fish, dairy products, fruits, vegetables, etc. Drink production and more specifically breweries offer intriguing potential applications as well. Because of the vast diversity of specific unit operations, which feature various heat transfer, microbiological and biochemical scenarios, a uniform design approach towards all LAES-based engineering solutions would hardly be possible, while concrete processing, storage and distribution technologies need to be analysed individually on a case-by-case basis.  
Conceptualization: D.P. and K.F.; Methodology: D.P. and S.A.; Analysis: LAES plant D.P., K.F. and B.S.; food factory: S.A. and K.F.; Checking: K.F. and S.A.; Visualization: K.F. and B.S.; Writing, review and editing. D.P., S.A., K.F. and B.S. All authors have read and agreed to the published version of the manuscript.  
The CryoHub Innovation Action received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 691761.  
The authors would like to thank all members of the CryoHub project consortium for the fruitful partnership and the useful discussions. The authors declare no conflict of interest.