Periodic Reporting for period 2 - START (SUSTAINABLE ENERGY HARVESTING SYSTEMS BASED ON INNOVATIVE MINE WASTE RECYCLING)
Reporting period: 2023-09-01 to 2025-01-31
START project proposes a unique technological solution based on the transformation of mining waste into materials for waste heat recovery, thus contributing to an efficient use of resources while promoting the use of green energy harvesting through thermoelectric systems. This approach is in line with the strategies outlined in the European Green Deal and in the EU Action Plans on Critical Raw Materials and on Circular Economy.
Current commercial thermoelectric devices incorporate p-type thermoelectric materials that are produced from expensive and scarce elements, namely tellurium, which also presents high risks due to potential geopolitical impacts. Consequently, START primary objective is to build an innovation ecosystem in the EU related to the development of sustainable and economically viable tellurium-free thermoelectric waste heat harvesting systems. This will be achieved by producing advanced sulphide thermoelectric materials that will incorporate discarded mining waste sulphides (mainly consisting of the tetrahedrite mineral series), as valuable secondary raw materials and present in many European mine wastes, to replace the tellurium-based thermoelectric materials. The main deliverable is associated with the demonstration of the feasibility of tellurium-free thermoelectric devices with the highest economic efficiency, suitable to be applied in waste heat recovery systems, such as the heat rejected from industrial processes. Additionally, recycling of mine wastes will have an impact on the environmental footprint of mines, on the reduction of their waste piles, on the increase of the economic potential of such sites and on the EU’s competitiveness in raw materials.
Current commercial thermoelectric devices incorporate p-type thermoelectric materials that are produced from expensive and scarce elements, namely tellurium, which also presents high risks due to potential geopolitical impacts. Consequently, START primary objective is to build an innovation ecosystem in the EU related to the development of sustainable and economically viable tellurium-free thermoelectric waste heat harvesting systems. This will be achieved by producing advanced sulphide thermoelectric materials that will incorporate discarded mining waste sulphides (mainly consisting of the tetrahedrite mineral series), as valuable secondary raw materials and present in many European mine wastes, to replace the tellurium-based thermoelectric materials. The main deliverable is associated with the demonstration of the feasibility of tellurium-free thermoelectric devices with the highest economic efficiency, suitable to be applied in waste heat recovery systems, such as the heat rejected from industrial processes. Additionally, recycling of mine wastes will have an impact on the environmental footprint of mines, on the reduction of their waste piles, on the increase of the economic potential of such sites and on the EU’s competitiveness in raw materials.
The implementation of the START project activities began on June 1st, 2022, and will last for 48 months (M). The project is structured into four interconnected technical work packages (WPs), each dedicated to a specific focus: (a) selection of suitable mine waste sites as source of tetrahedrite-tennantite mineral samples, physical mineral separation and concentration, (b) materials modelling and processing of thermoelectric materials, (c) thermoelectric device production, validation and demonstration and (d) materials characterisation.
The work conducted and the key achievements up to M32 are summarised as follows:
• The project has identified suitable mining waste sites across Europe. By collecting and processing hundreds of raw samples, approximately 40 kilograms of tetrahedrite concentrate were obtained, which are being used to produce mineral-based tetrahedrite thermoelectric materials. This material serves as a sustainable alternative to tellurium, currently a crucial raw material for thermoelectric technology, but which presents high risks due to scarcity and potential geopolitical impacts.
• Advances in the production of thermoelectric materials, achieved by combining two powder technologies, high energy ball milling and spark plasma sintering:
- For the high energy ball milling, the production has been increased from a pre-pilot scale (around 300 g per batch) to a pilot scale (about 1000 g per batch).
- For the spark plasma sintering, production efficiency has improved by increasing output from one pellet to twelve per sintering cycle.
• Significant advances have been made in materials characterisation, a continuous process needed to ensure quality and performance, as well as in the development of thermoelectric devices, supported by extensive modelling, simulations, and experimental testing:
- A record-setting thermoelectric performance was achieved for a synthetic tetrahedrite material with one of the highest values reported to date. This was made possible by a detailed optimisation process of both the material composition and processing conditions.
- A thermoelectric material containing a specific amount of tetrahedrite concentrate has been successfully demonstrated, proving that recycled secondary raw materials can be integrated into the processing of materials with competitive performance.
- Selection of the n-type TE material based on its performance, mechanical/chemical compatibility with tetrahedrites and practical experience within the consortium. Consequently, the magnesium-antimony based alloys has been selected as baseline for the project while the silicon-germanium based alloys will serve as a back-up solution.
- A 45 x 45 mm thermoelectric module for medium-temperature applications (around 350 ºC) has been fabricated, and work is ongoing to develop a flexible module for low-temperature applications.
• Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) analyses are being carried out to compare conventional lead/bismuth telluride devices with the new tetrahedrite-based alternatives. These studies aim to highlight the environmental and economic benefits of using sustainable materials in thermoelectric technology.
Overall impact
The achievements made so far through the implementation of the START project position European industry at the forefront of thermoelectric innovation, improving its capacity to develop sustainable renewable energy ecosystems and reinforcing its technological sovereignty in next-generation materials and device manufacturing for these systems. It also supports the EU’s goals under the Critical Raw Materials Act and align with United Nations Sustainable Development Goals, specifically, affordable and clean energy, industry innovation, and sustainable cities.
In summary, the START project is laying the foundations for a sustainable thermoelectric ecosystem in Europe, strengthening European leadership in sustainable energy technologies.
The work conducted and the key achievements up to M32 are summarised as follows:
• The project has identified suitable mining waste sites across Europe. By collecting and processing hundreds of raw samples, approximately 40 kilograms of tetrahedrite concentrate were obtained, which are being used to produce mineral-based tetrahedrite thermoelectric materials. This material serves as a sustainable alternative to tellurium, currently a crucial raw material for thermoelectric technology, but which presents high risks due to scarcity and potential geopolitical impacts.
• Advances in the production of thermoelectric materials, achieved by combining two powder technologies, high energy ball milling and spark plasma sintering:
- For the high energy ball milling, the production has been increased from a pre-pilot scale (around 300 g per batch) to a pilot scale (about 1000 g per batch).
- For the spark plasma sintering, production efficiency has improved by increasing output from one pellet to twelve per sintering cycle.
• Significant advances have been made in materials characterisation, a continuous process needed to ensure quality and performance, as well as in the development of thermoelectric devices, supported by extensive modelling, simulations, and experimental testing:
- A record-setting thermoelectric performance was achieved for a synthetic tetrahedrite material with one of the highest values reported to date. This was made possible by a detailed optimisation process of both the material composition and processing conditions.
- A thermoelectric material containing a specific amount of tetrahedrite concentrate has been successfully demonstrated, proving that recycled secondary raw materials can be integrated into the processing of materials with competitive performance.
- Selection of the n-type TE material based on its performance, mechanical/chemical compatibility with tetrahedrites and practical experience within the consortium. Consequently, the magnesium-antimony based alloys has been selected as baseline for the project while the silicon-germanium based alloys will serve as a back-up solution.
- A 45 x 45 mm thermoelectric module for medium-temperature applications (around 350 ºC) has been fabricated, and work is ongoing to develop a flexible module for low-temperature applications.
• Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) analyses are being carried out to compare conventional lead/bismuth telluride devices with the new tetrahedrite-based alternatives. These studies aim to highlight the environmental and economic benefits of using sustainable materials in thermoelectric technology.
Overall impact
The achievements made so far through the implementation of the START project position European industry at the forefront of thermoelectric innovation, improving its capacity to develop sustainable renewable energy ecosystems and reinforcing its technological sovereignty in next-generation materials and device manufacturing for these systems. It also supports the EU’s goals under the Critical Raw Materials Act and align with United Nations Sustainable Development Goals, specifically, affordable and clean energy, industry innovation, and sustainable cities.
In summary, the START project is laying the foundations for a sustainable thermoelectric ecosystem in Europe, strengthening European leadership in sustainable energy technologies.