Periodic Reporting for period 1 - H2E (A thermoelectric generator for low-grade heat to electricity/hydrogen conversion (H2E))
Berichtszeitraum: 2022-09-01 bis 2024-08-31
In industrial process and during our most common daily activities, vast amounts of energy is lost in the form of low-grade heat. In Flanders, Belgium, the heat wasted to the atmosphere by the chemical industry is estimated at 4.9 TWh/y (2015). This astonishingly represents circa 10% of the yearly energy production by Belgian nuclear power plants. H2E aims to innovate heat-to-electricity conversion, unlocking the valorisation potential of low-grade residual heat. Heat-to-power conversion can be achieved by thermoelectric generators (TEGs), devices that exploit the Seebeck effect to build up an electric potential across a stack of semiconductors subjected to a temperature difference. This physical effect has long been known, but widespread application has remained limited because of the low efficiency (less than 5%) and high cost of available semiconductors, often containing rare metals and featuring high toxicity and poor thermal stability. Using less expensive semiconductor materials and increasing efficiency are the main challenges to broaden the application field of TEGs. H2E proposes a new approach to enable improved TEGs using a thermo-electrochemical-hydrogen production device (TEC-H) based on recently discovered, robust, low cost, non-toxic porous semiconductor materials. These new semiconductors are implemented in an original design, mounting them in stacks to produce a TEC-H device that is modular and exhibits good scalability. H2E will enable valorisation of low-grade waste heat in the temperature range below 100 °C, a range currently not exploited in industry. Besides industrial waste heat, also low-grade geothermal heat represents huge potential. In this way H2E will contribute to a more energy-efficient and low-carbon future, in line with Europe’s long-term strategy to become climate-neutral by 2050 as set by the European Commission in The European Green Deal.
The work performed within H2E consisted in the synthesis of novel organic and inorganic porous semiconductor materials, the fabrication of thermocouples, their physical-chemical characterisation and investigation of their thermoelectric properties. The synthesised materials have been characterized by X-ray diffraction, N2 adsorption, Nuclear Magnetic Resonance spectroscopy and X-ray photoelectron spectroscopy.
Several methods have been tested to produce pellets and films based on the novel materials synthesised during the project, among them, physical assembly of powders (pressing), drop casting, dip coating, dry or wet powder pressing with mixing agents. Surface treatments were evaluated for their potential to improve the agglomeration of the materials during pellet production. The transport properties of the produced pellets and films have been characterized by thermal and electrical measurements.
By controlling the degree of doping in the semiconductors, the electrical conductivity of pressed pellets could be increased by circa one order of magnitude. Further increase in the conductivity has been achieved by mixing the semiconductors with commercially available semiconducting polymers, which is expected to positively impact their heat-to-electricity conversion efficiency.
Several methods have been tested to produce pellets and films based on the novel materials synthesised during the project, among them, physical assembly of powders (pressing), drop casting, dip coating, dry or wet powder pressing with mixing agents. Surface treatments were evaluated for their potential to improve the agglomeration of the materials during pellet production. The transport properties of the produced pellets and films have been characterized by thermal and electrical measurements.
By controlling the degree of doping in the semiconductors, the electrical conductivity of pressed pellets could be increased by circa one order of magnitude. Further increase in the conductivity has been achieved by mixing the semiconductors with commercially available semiconducting polymers, which is expected to positively impact their heat-to-electricity conversion efficiency.
Results beyond the state of the art:
- Synthesis of new organic and inorganic porous semiconductor materials
- An increase of circa one order of magnitude in the electrical conductivity was achieved for the produced materials compared to what has been reported in the literature for the same class of semiconductors
Impact of the results:
- The new materials synthesised in this project strengthen the list of available porous semiconductor materials and may find new applications in other fields
- The results provide a route for the enhancement of electrical conductivity in the class of semiconductors investigated in the project
Key needs to ensure further uptake and success:
- Further research is needed to still enhance the electrical conductivity of the materials and achieve the levels required for applications as thermoelectric materials
- Further research is needed to test the application of the new materials in other fields
- Synthesis of new organic and inorganic porous semiconductor materials
- An increase of circa one order of magnitude in the electrical conductivity was achieved for the produced materials compared to what has been reported in the literature for the same class of semiconductors
Impact of the results:
- The new materials synthesised in this project strengthen the list of available porous semiconductor materials and may find new applications in other fields
- The results provide a route for the enhancement of electrical conductivity in the class of semiconductors investigated in the project
Key needs to ensure further uptake and success:
- Further research is needed to still enhance the electrical conductivity of the materials and achieve the levels required for applications as thermoelectric materials
- Further research is needed to test the application of the new materials in other fields