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Page 2 of 17 Lekbir et al. Energy Mater. 2025, 5, 500101 https://dx.doi.org/10.20517/energymater.2025.46

INTRODUCTION
The global energy demand has significantly increased due to the widespread use of electronic devices . In
[1]
this context, the world faces two major challenges: meeting the growing energy demand and reducing the
environmental impact associated with traditional power plants . Renewable energy sources, such as wind,
[2]
[3]
solar, and thermal, can offer sustainable power generation . Various systems have been introduced to
harvest these energy sources and convert them into electricity including conventional energy conversion
[4]
methods, such as wind turbines, or microscale technologies, such as thermoelectric generators (TEGs) .
TEGs are solid-state devices that convert temperature gradients between hot and cold sides into
[5]
electricity . These devices rely on thermoelectric materials that transport charge carriers and phonons,
[6]
enabling direct heat-to-electricity conversion . TEG modules are compact, scalable, and can be easily
integrated into systems where a temperature gradient is present . In several applications, TEG modules
[7]
[8]
have demonstrated unique potential for waste heat harvesting . Numerous studies have explored TEG
integration in solar energy systems, automotive applications, and industrial waste heat recovery, resulting in
diverse module designs with varying materials and sizes . The findings indicate that these TEGs can
[9]
operate continuously as long as a temperature difference is maintained, making them a favorable option for
power generation in applications where other renewable energy systems experience intermittent
production . However, while their efficiency is lower compared to other renewable sources, advancements
[10]
in materials have improved their performance . In this context different studies have examined the impact
[11]
of material selection on TEG performance, evaluating both traditional thermoelectric materials (e.g., Bi Te ,
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PbTe, and SiGe) and recently developed alternatives such as CoSb , GeTe, Sn Se, BiCuSeO, SWNTs/
X
3
[12]
PEDOT, Bi Sb Te + graphene , etc. Other researchers explore the performance of flexible TEGs using
0.48
3
1.52
advanced materials, where the flexibility of the materials is crucial for applications in wearable devices,
portable electronics, and other flexible energy harvesting systems [13-16] . However, these studies mainly assess
TEG efficiency based on key material parameters, overlooking environmental impact and long-term
performance, both crucial for commercial scalability.
Recently, several studies have investigated the environmental impact of TEG materials. Chan et al. analyzed
four commercial TEG modules, assessing efficiency, reliability, and long-term performance . However,
[17]
their study highlighted gaps in data on material properties, size limitations in commercial models, and the
lack of a detailed greenhouse gas (GHG) emissions analysis. Lan et al. examined the environmental and
economic impact of TEG leg geometry and structure, considering material properties and heat
dissipation . Their findings suggest that optimizing TEG configurations can reduce CO emissions by
[18]
2
1.0%-72.1%, especially for low hot-source temperatures and high-ZT materials. However, these
modifications adversely affect economic viability and thermal efficiency. Ibn-Mohammed et al. conducted a
comprehensive analysis of the techno-environmental impact of various TEG modules, highlighting the
significant influence of material selection . Their findings show that fabrication requires substantial
[19]
electrical energy, with non-oxide materials such as Bi Te posing high toxicity risks due to tellurium and
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antimony. In contrast, oxide-based materials demonstrate lower toxicity but are associated with higher
environmental impacts of cobalt oxide. Soleimani et al. assessed the environmental impact of TEG materials
during production, considering resource consumption, emissions, waste, energy demand, and global
warming potential . Their analysis of inorganic, organic, and hybrid materials revealed that inorganic
[20]
types generally have the highest impact due to energy-intensive manufacturing, except for Bi Te , which had
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the lowest impact among all studied materials. These studies highlight the growing concern regarding the
environmental footprint of TEG materials, yet significant research gaps remain. Therefore, advancing
sustainable TEG systems requires further research to optimize energy conversion efficiency while