Aluminium for the energy transition

Renewable energies will need to be stored in huge quantities over longer periods in order to achieve the energy transition. Over the last few years, there has been an increasing amount of research into the use of metals – especially iron – as carbon-free chemical energy carrier. The A-STEAM project headed by Professor Christian Hasse, Institute for the Simulation of Reactive Thermo Fluid Systems, focuses on the use of the metal aluminium as an alternative energy carrier.

Aluminium can store a lot of energy and has already been used, for example, as a high-energy booster for the Ariane 5 launch rocket. This high storage capacity could now be utilized to decarbonise the industrial sector using a highly innovative process in which aluminium is oxidized, i.e. burnt, at high temperatures using water vapour as oxidant to produce two highly valuable products – high-temperature heat and hydrogen – that can be used, for example, to generate electricity or for synthesis processes in the chemical industry.

The ability to flexibly generate hydrogen on a large scale on site is an especially important aspect that addresses a previously unresolved issue facing the future hydrogen industry – namely the transport and the storage of hydrogen. It must be transported at either very low temperatures (-253°C) or at high pressures (>300bar), which makes it a very energy intensive process with associated energy losses. In the A-STEAM project, the hydrogen itself is not transported but aluminium is used as an energy carrier so that hydrogen can be produced on site as and when it is required. Aluminium is thus an efficient carrier of hydrogen, without the disadvantages associated with the transport of hydrogen, and also has outstanding properties for its long-term storage.

“I view the ERC Advanced Grant as a seed for the growth of research into the use of metals as energy carriers – which is a rapidly expanding field of research with its first commercially available products, although they still have low levels of efficiency overall”, says Professor Christian Hasse. By generating heat at high temperatures, it will be possible to achieve higher thermodynamic efficiencies.

The combustion of aluminium using water vapour under pressure is a multi-scale and multi-physics process that has largely been unexplored up to now. This is the challenge facing A-STEAM: The research needs to combine and investigate all of these different scales, i.e. the entire scientific chain from the combustion of single particles through to turbulent flames involving millions of aluminium particles. A combination of scientific methods will be used for this purpose: advanced modelling, high-performance computing and tailored experiments. The core element of the research in A-STEAM will be high-resolution simulations on high-performance computers (HPC) using advanced numerical methods. Most of the simulations will be carried out on the “Lichtenberg II” high-performance computer at TU Darmstadt.

A-STEAM builds on the research into the use of iron as an energy carrier in the Clean Circles cluster research project in the Carbon Neutral Cycles (CNC) research profile at TU Darmstadt. The researchers working on this project at TU Darmstadt are focusing on chemical energy carriers in general such as hydrogen, ammonia or e-fuels for renewable energies. Over the last few years, the Clean Circles project has carried out pioneering global research into the use of iron as a highly innovative, carbon-free energy carrier. The A-STEAM project will focus instead on aluminium, which has an even higher energy density than iron. The high-temperature combustion of aluminium using water vapour will not only produce heat but also hydrogen for the first time.

bjb