Sustainable Waste-to-Watts: A Modular Bi2Te3 Thermoelectric System for Textile Waste Valorization

Abstract

Global textile production generates over 100 million tonnes of cutting scraps and end-of-life garments annually, most of which are landfilled or incinerated, releasing greenhouse gases and microplastics. To valorize this waste and harvest low-grade heat, we introduce a circular “sandwich” prototype combining dark-dyed acrylic–wool off-cuts with commercial 40 × 40 mm Bi?Te?thermoelectric modules. In laboratory trials under 1 000 W/m² simulated solar irradiation, each module produced an average 0.43 W (?4.3 % conversion efficiency) and stored 2.18 Wh in a 5-h charge test via an MPPT boost-charger into a 3.7 V Li-ion cell. Scaling to a 30-panel array at an industrial partner’s facility (Kapoor Overseas) delivered 129 W peak and 654 Wh/day, sufficient to power temperature sensors, LED indicators, and ventilation fans continuously. A preliminary techno-economic analysis estimates a capital cost of ?2 000/W, a 5–6 year payback at ?7.5/kWh tariff, and an LCOE of ?8–10/kWh. Our results demonstrate that waste-fabric?based thermoelectric harvesting is a viable complement to photovoltaics, especially under diffuse light and in modular deployments. We outline future directions—enhanced cooling, UV-protective coatings, hybrid PV-TEG integration, and smart load matching—to further improve performance and drive commercial adoption

Introduction

Background & Problem

The world generates over 100 million tonnes of textile waste annually, most of which ends up in landfills or is incinerated—releasing greenhouse gases and microplastics. While the push for sustainability grows, this waste stream remains largely untapped for energy reuse.

Proposed Solution: Thermoelectric "Sandwich" from Textile Waste

This study explores how dark-dyed textile off-cuts (e.g., sweater scraps) can be repurposed into thermoelectric generators (TEGs). By leveraging the Seebeck Effect, heat absorbed by the dark fabrics (from sunlight or industrial waste heat) is converted into electricity using Bi?Te? thermoelectric modules.

System Design

A modular prototype is built with the following layers:

• Top: Dark fabric (heat absorber)

• Middle: Thermal interface and Bi?Te? module

• Bottom: Aluminum heat sink (cold side)

This sandwich structure captures heat from the fabric’s surface and creates a temperature gradient (ΔT) across the TEG module, generating power without moving parts.

Material Justification

• Bi?Te? was chosen for its high Seebeck coefficient (~200 μV/K), low thermal conductivity, and optimal performance in ambient to 100°C ranges—matching the fabric’s heat profile.

• Modules were sourced online and paired with standard thermal pads and heat sinks.

• Factory waste fabrics were collected from two Indian textile manufacturers, ensuring real-world material relevance.

Experimental Performance

• Under 1,000 W/m² sunlight, the system achieved a steady ΔT of 35°C, generating about 0.43 W (or 4.3% efficiency) per module.

• When scaled (e.g., a 30-panel array on a 20 m² rooftop), the system produced ~650 Wh/day, used to power IoT sensors and ventilation fans in a real factory.

Comparison with Other Renewable Methods

• Power density is lower than PV (~43 W/m² vs. 150–200 W/m²), but the TEG system:

  • Works better under diffuse or shaded conditions

  • Requires no moving parts or complex maintenance

  • Can be retrofitted to existing surfaces

  • Utilizes waste, supporting a circular economy

Other textile-based energy methods (e.g., pyrolysis, anaerobic digestion, solar-thermal mats, triboelectric, or PV fabrics) show promise but lack scalability, cost-efficiency, or rely on purpose-made textiles—not factory scraps.

Literature Gap

Few studies combine:

• Genuine textile off-cuts (not lab-made fabrics)

• Commercially available TEGs

• Side-by-side benchmarking with other energy extraction methods

The study fills this gap by delivering reproducible results and a cost-conscious design framework using waste materials.

Key Findings

• The prototype stores ~2.18 Wh in a Li-ion battery after 5 hours of sunlight.

• Real-world deployment at a factory validated scalability and performance.

• Unique advantages include modularity, resilience to shading, and compatibility with low-grade heat (from sun or industrial processes).

Limitations

• Low power density—requires more surface area than PV.

• Thermal management challenges at scale.

• Fabric degradation from UV or moisture exposure.

• Economic feasibility (~?45/W) still needs optimization.

Proposed Improvements

• Better heat sinks or thermal concentration

• UV- and water-resistant coatings

• Hybrid PV-TEG panels

• Smart control systems for load optimization

With these, efficiency could rise to 7–8%, and cost per watt could fall 30–40%.

Conclusion

This study has demonstrated that a simple “sandwich” of dark-dyed textile waste and a commercial 40 × 40 mm Bi?Te?thermoelectric module can reliably convert low-grade solar heat into electricity. Key findings include: 1) Module Performance: Each module generated an average 0.43 W under one-sun (1 000 W/m²) illumination, corresponding to a conversion efficiency of ? 4.3 % (Section 4.2). 2) Energy Storage: When routed through an MPPT boost-charger into a Li-ion cell, each module stored 2.18 Whover a 5 h simulated-sun run (Section 4.3). 3) Panel Scaling: A 10-module panel yields 4.3 W peak and, in a 30-panel rooftop array at Kapoor Overseas, produced ~654 Wh/day—enough to power low-power sensors and fans continuously (Section 5.3). 4) Comparative Context: While delivering only ~3 % of the area-normalized energy of PV, the textile-TEG array excels in diffuse light, modular deployment, and waste-material valorization (Section 5.1–5.2). Next Steps To advance this platform toward real-world readiness, we recommend: • Durability Testing: Conduct long-term outdoor trials (>12 months) to assess textile UV and moisture degradation. • Thermal-Management Enhancements: Integrate micro-fin or heat-pipe backs for improved ?T and higher power. • Hybrid Architectures: Combine with thin-film PV or thermal concentrators to boost total yield per square meter. • Control Strategies: Implement dynamic load-matching via microcontrollers to maintain optimal operating point under variable irradiance. Techno-Economic Outlook A preliminary cost estimate places panel installation at ? 2 000/W, implying ~?8 600 per 4.3 W panel. For the 30-panel array (peak 129 W), capital cost is ~?258 000. At an average yield of 0.65 kWh/day and an industrial electricity tariff of ?7.5/kWh, annual savings approach ?17 850, yielding a payback period of ? 5–6 years. The levelized cost of energy (LCOE) is therefore on the order of ? 8–10/kWh, which—while higher than rooftop PV today—may become competitive when accounting for waste-material valorization incentives, hybrid system synergies, and low-maintenance operation. In conclusion, the fabric-TEG sandwich represents a viable proof-of-concept for circular-economy energy harvesting. With targeted design and economic optimizations, it has the potential to become a complementary, low-footprint power source for distributed sensing, lighting, and auxiliary loads in both industrial and urban settings.

References

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Copyright

Copyright © 2025 Sahib Kapoor. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.