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Lekbir et al. Energy Mater. 2025, 5, 500101 https://dx.doi.org/10.20517/energymater.2025.46 Page 9 of 17

Figure 3. Energy inventory of raw materials used in each leg of a TEG.

material portion and composition on the CEC index per TEG leg. Specifically, the embodied energy index
of each material within the TEG legs is directly related to its proportion in the leg. Notably, Tl and Ge
exhibit the highest embodied energy indices, particularly in TEG8, due to their higher proportions
compared to other TEG modules.

On the other hand, the total CEC for each TEG module is presented in Table 3. It is evident that the overall
CEC for each leg depends on multiple factors, including composition, density, and the weight of each
material. Notably, TEG8 exhibits a significantly high equivalent consumed energy of approximately
24.79 MJ/leg for the n-type leg and 27.41 MJ/leg for the p-type leg. This is primarily attributed to the high
embodied energy indices of 464.96 and 214.41 MJ/kg for the n-type and p-type legs, respectively, as well as
the increased leg weight. These findings indicate that the manufacturing phase of TEG8 has the highest
energy consumption among all TEG systems. Specifically, the energy consumption during the
manufacturing phase of TEG8 is approximately 80.78%, 46.61%, 55.24%, 37.34%, 47.19%, 42.33%, and
54.71% higher compared to TEG1 through TEG7, respectively.

Furthermore, the embodied energy of the ceramic layer and copper electrodes was estimated, and the results
are summarized in Table 4. The findings indicate that the CEC associated with these components is
relatively low, underscoring their minor contribution to the CEC of the TEG module. As a result, the overall
energy consumption during the manufacturing phase of different TEG modules is predominantly