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Spotted: How can we transport energy to where we need it? This may seem like an abstract question, but it is an important one for the global energy transition. We can, of course, move energy as electricity through transmission lines, but this is only part of the picture. One of the characteristics of fossil fuels that has proved useful to humanity is the fact that the energy they contain can be taken from its source (the ground) and moved to wherever it is needed by road, rail, or ship. However, the equation is not so simple for renewable energy sources such as solar and wind power.

Today, renewable energy can be stored and moved through electrochemical and thermal batteries. But these solutions have a much lower energy density than fossil fuels and are only suitable for short journeys or stationary storage. Others suggest that hydrogen or ammonia – fuels that can be produced using renewable electricity – could act as methods of long-distance energy transportation. But these two solutions face safety and energy efficiency challenges that call into question their economic sense.

Now, startup Found Energy has come up with an entirely novel method of energy transportation: aluminium energy storage packs. These are based on the idea of extracting energy from aluminium by accelerating the rusting process to produce heat and hydrogen.

All aluminium contains potential energy in its chemical bonds (around 8.6 megawatt-hours of stored energy per tonne of aluminium), and this energy primarily derives from the electricity used to smelt the metal. However, if left to its own devices, aluminium reacts with oxygen in the air forming a ‘protective’ oxide layer that locks away this potential energy. Found Energy’s fundamental innovation is the development of a catalyst that strips away the oxide layer making the aluminium reactive. The ‘activated’ aluminium can then be added to a reactor, which is then flooded with water. The water reacts with the metal, producing heat and hydrogen, which can be used directly in industrial processes or as a fuel respectively.

After the reaction between the water and the aluminium takes place, the material left over is aluminium hydroxide, which is already used in cement, fire suppressants, pharmaceuticals, and, crucially, as the primary raw material in the production of new aluminium.

The aluminium used in Found Energy’s packs is scrap that would otherwise be landfilled (and the potential energy wasted). What is more, the aluminium smelting process is already electrified, which means that, as the grid decarbonises, much of the energy stored in aluminium will become ‘green’, as it will have originally come from a renewable source.

It is important to note, however, that while aluminium smelting is electrified, the production of the intermediate product alumina currently relies on fossil fuels and is more difficult to convert to electric power. This means that some of the energy contained in aluminium will likely retain a carbon cost even once the grid is decarbonised. However, there are some early efforts to explore the electrification of alumina refining and other techniques such as the use of biogas and carbon capture could help mitigate alumina’s carbon footprint.

Energy storage is an important, if complex, topic and Springwise has spotted several innovations in this area. This includes a high-temperature thermal energy storage system for industry, and an iron-air battery for grid-scale energy storage.

Written By: Matthew Hempstead