## 7 The Case Study
### Kinetic Energy Harvesting Materials Assessment
#### 7.4.1 t-TENGs Materials  
Textile-based Triboelectric Nanogenerators (t-TENGs) present a promising material solution for generating electricity from the movement of large crowds, making them especially suitable for high-foot-traffic areas such as the Al-Haram Mosque in Saudi Arabia [119]. While an analogy can be drawn between crowded sports complexes, as discussed in [119], and the mosque, Al-Haram experiences a significantly higher and continuous flow of millions of pilgrims, particularly during peak periods such as Hajj and Ramadan. This constant foot traffic provides a substantial and consistent source of mechanical energy, which could be harnessed by integrating t-TENG materials into the flooring to power lighting or low-energy devices within the mosque. The inherent modularity of textile-based TENGs allows them to be engineered into flexible and customizable mats or carpets that can seamlessly blend with the mosque's aesthetic design. These textile modules can cover extensive foot-traffic areas and are easily folded or stored during cleaning and maintenance, aligning well with the mosque's regular upkeep routines. Regarding the suitability of t-TENG materials for the mosque's environmental conditions, recent advancements have significantly improved their durability and resistance to environmental challenges. Research involving polyester-based TENGs and advanced coating techniques has enhanced their ability to withstand repeated mechanical stress and harsh conditions such as high humidity, temperature fluctuations, and dust exposure [120]. These conditions are common in the climate surrounding the Al-Haram Mosque. Such improvements in material properties underscore the potential of t-TENGs as a robust and reliable energy-harvesting solution in heavily used areas. Although t-TENG materials may not currently produce enough electricity to operate heavy electrical systems, they are ideal for powering low-energy applications, such as lighting systems, sensors for air-quality monitoring, or small digital displays. Furthermore, integrating t-TENG-powered sensors could enable autonomous monitoring of environmental parameters such as temperature, humidity, and CO\({}_{2}\) levels, thereby enhancing comfort and safety without relying on external power sources. Despite these advantages, several challenges remain for the practical implementation of t-TENG materials. The current power output of these textiles remains relatively limited, suggesting that combining them with other energy sources may be necessary to satisfy higher energy demands. Moreover, although recent advancements have improved durability, textile-based TENGs remain susceptible to wear under continuous heavy foot traffic. Addressing this issue may require the application of high-durability coatings or the selection of more robust materials. Additionally, the extreme conditions at the Al-Haram Mosque--including high temperatures, dust, and humidity--could negatively impact the efficiency of t-TENG materials. Hybrid triboelectric systems incorporating polymers with conductive fillers have demonstrated enhanced charge generation and retention capabilities [89; 120]. Their flexibility and lightweight characteristics make this composite material ideal for integration into thin, large-area devices, further reinforcing the potential of textile-based TENGs as a viable solution for kinetic energy harvesting in environments with substantial foot traffic. Therefore, to estimate the power harvesting using this material within the Al-Haram space, the following assumptions are set: (a) Energy per footstep is ~0.1 Joule (conservative estimate), energy per full prayer cycle is ~1.0 Joule (due to multiple postures), average people per day is ~500,000 (can exceed 2 million in Hajj and Ramadhan), average prayer cycles/day/person is 5 (compulsory) + 2 (optional) = 7, mat-covered area (example) is 10,000 m\({}^{2}\) (selected prayer area), people per m\({}^{2}\) in congregation is ~2.5.