## 2 Literature Review
### SHTES Systems in Greenhouses
#### 2.2.2 Underground Thermal Energy Storage (UTES) System as SHTES System
By overlaying a double-layer membrane for the greenhouse in Mode B, the temperature was even 6.6 \({}^{\circ}\)C higher than in Mode A, since the system's insulation efficiently inhibits heat loss. When the system was further heated intermittently, Mode C maintained the same energy efficiency as Mode B while conserving 40% of the input energy. Furthermore, the GBES system's coefficient of performance (COP) may reach up to 5.9, 1.6 times greater than a traditional geothermal greenhouse, at a relatively low capital and operational cost. The suggested GBES technology showed potential for low-cost temperature stabilization in a greenhouse. The schematics and pictures of the proposed system by [PERSON] et al. [45] are demonstrated in Figure 25.  
Figure 25: The schematics and pictures of the proposed system by [PERSON] et al. [45]. (**a**) lower pipe buried at a depth of 1.2 m, (**b**) upper pipe buried at a depth of 0.7 m, (**c**) propeller fans positions, and (**d**) greenhouses Nos. 1 and 2. pictures. Vertical Borehole Thermal Energy Storage (VBTES)  
[PERSON] et al. [46] investigated the long-term operation and environmental impacts of a sizable ground source heat pump (GSHP) system that heated and cooled industrial greenhouses in a cold climate using both field data and a numerical simulation. In the northern Japanese province of Hokkaido, a sizable vertical GSHP system was set up to heat and cool twelve greenhouses. The system's highest heating and cooling capacities are 640 and 648 kW, respectively. The system was observed and examined between October 2010 and May 2011. After eight months of operation, the ground temperature at a depth of 40 m dropped from around 7.8 \({}^{\circ}\)C to 0 \({}^{\circ}\)C. The simulation's findings imply that the system's performance would not be materially jeopardized if the heat exchange rate was maintained for several years. Case studies addressed the danger of running the system under imbalanced heating and cooling loads. Operating the system when the heat extraction is much more significant or lower than the heat injection is made less risky by groundwater flow. The schematics of the proposed approach by [PERSON] et al. [46] are demonstrated in Figure 26.  
An experimental investigation was conducted by [PERSON] et al. [47] to evaluate the effectiveness of a novel conic basket geothermal heat exchanger (CBGHE) for greenhouse cooling. A sequence of parallel coils implanted at a depth of three meters usually made up the arrangement. The tests were in June 2014, on June 7 and 8. The outcomes demonstrated that the CBGHE system could be applied to greenhouse cooling in Mediterranean locations like Tunisia. The most considerable amount of heat the CBGHE could transmit to the ground during the experiment was around 8 kW. With a recorded mass flow rate of 0.08 kg\(\cdot\)s\({}^{-1}\), the most significant average temperature difference between the CBGHE system's intake and output was about 30 \({}^{\circ}\)C. Within the greenhouse, the air temperature dropped by approximately 12 \({}^{\circ}\)C. The schematics of the proposed system by [PERSON] et al. [47] are demonstrated in Figure 27.  
Figure 26: The schematics of the proposed system by [PERSON] et al. [46].