Energy carriers

The transition from fossil fuels to renewable energy requires storing seasonally high quantities of energy and transporting it from where renewable energy is produced to areas of high energy demand. Metal powder, and in particular iron powder, was recently proposed as a high-energy density carrier. The idea is to store surplus renewable energy generated in the summer by converting iron oxide powder (rust) into iron. The stored energy is released by burning iron. The combustion, or oxidation, of iron powder produces iron oxide powder that can be recycled back in a closed loop, with no CO2 emissions as long as the recycling path is powered using renewable energy.

The combustion (high-temperature oxidation in liquid state) of pure iron powder presents several limitations, such as pyrophoricity; toxic nanoparticle emission; particle inflation and micro-explosions; … The main hypothesis of our research group is that the mechanisms at the origin of these problems can be modified by controlling the fuel chemistry and microstructure.

 
These drawbacks can also be avoided by oxidizing the iron fuel at lower temperatures (solid-state). New challenges are faced, mainly the deactivation of the fuel over cycling due to strong morphological changes (sintering, pore and crack formation, gas percolation, …). Another focus of our group is the topological evolution of iron foams over low-temperature redox cycling.

The recycling of oxidized iron products can be conducted without CO2 emissions using either hydrogen-based direct reduction, or direct electrolysis. Another research topic of our group is the influence of iron electrolysis parameters on the morphology and microstructure of the reduced iron. 

The combustion of iron powder is conducted in collaboration with Pr. Francesco Contino, TFL, in a fully interdisciplinary approach, combining combustion and material science. Iron combustion is investigated at the multi-particle scale, in a design cyclonic burner; and at the particle scale, using state-of-the-art particle levitator with laser ignition, and high-speed diagnostics. Experimental investigations are coupled with CFD (multi-particle) and Phase Field (single particle) numerical simulations.

Solid-state chemical reactions are investigated using thermogravimetry and mass spectrometry, while the electrochemical reduction of iron oxide is studied in alkaline media under galvanostatic conditions. The kinetic analysis of the chemical reactions is coupled with the microstructural and chemical evolution of the fuel at different scales (nm - µm – mm).

The successful designed of tailored high-energy storage technology, will present a tremendous environmental, geopolitical, and economic impact, as it will strengthen our independence from fossil fuels.
 

Researchers

• PhD students: Lillian Ahmad, Bénédicte Kuypers, Killian Michel, Chouaib Difallah, Robin Thonon 
• Senior scientists / postdoc researchers: Hugo Keck 

Funding sources:

• ERC Starting-grant: FeFES
• Win4Excellence : EFES
• Weave DFG-FNRS: FIRE