Power-to-Al: storing energy in aluminum

Store renewable energy in aluminum in the summer to generate electricity, hydrogen or heat when needed. Even after months and months.

The European research project Reveal, funded by the Horizon Europe program, launched in July this year, is working on this task.

The researchers gave themselves 4 years to develop a new storage solution based on “Power-to-Al”, from electricity to aluminum.

The concept relies on the conversion of aluminum oxide into aluminum through electrolysis, adapting the technique to create a continuous energy storage cycle.

The project has a specific objective: to demonstrate the feasibility of the Power-to-Al storage cycle and the advantages over other storage technologies in terms of cost and impact.

According to initial estimates, a single cubic meter block of aluminum can chemically store about 23.5 megawatt hours, more than 50 times a lithium-ion battery. In summary, it can power a medium-sized house for 2 full years.

How to load the aluminum?

The Reveal team proposes to load aluminum balls with a diameter of 1 mm.

During the charging process, the excess renewable energy would be used to convert the aluminum oxide into pure elemental aluminum.

It is an industrial electrolysis process that requires temperatures around 800 ° C, as well as new inert electrodes, which avoid the emissions of current aluminum smelting processes.

The team estimates that it will be possible to load an aluminum redox system like this with an efficiency of around 65%.

All the materials necessary for the realization are relatively inexpensive (even from scrap or recycling) and easy to find, store and transport.

While to unload the aluminum?

To use the accumulated energy, simply reconvert it. This can be done at low temperatures, using aluminum-water reactions below 100 ° C.

These reactions generate aluminum hydroxide and pure hydrogen, which can be run directly in a PEM fuel cell stack for conversion to electricity.

Obviously, the process and the fuel cell also generate heat, which can be recovered to heat the rooms or for domestic hot water.

The recharging process would be performed at specific facilities, and the “charged” aluminum would then be made available to be “dumped” in condominiums, industrial facilities and even individual homes, when a compelling aluminum-hydrogen conversion system is developed. . After all, the necessary equipment is relatively simple and requires little maintenance.

In addition, the team analyzed the entire life cycle of the project and speaks of only € 0.09 per kWh. This makes it quite interesting, and it is no coincidence that Reveal works hard to implement practical solutions to this new energy storage concept.