Solar energy from aluminum balls becomes hydrogen for dark winters

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Scientists from Switzerland intend to use solar-charged metal balls to produce hydrogen and heat. Up to fifty times more energy can be stored in aluminum than in lithium-ion batteries.

This makes it a promising form of energy storage, especially in regions where winter solar is scarce.

The great difficulty of renewable energy has been extensively discussed in the past: the sun and the wind are not consistent energy sources. Consequently, the search for efficient energy storage solutions is ongoing. This allows us to retain excess solar and wind energy until night, cloudy, or windless conditions occur.

No sunlight in winter

In regions distant from the equator, the irregularity of a renewable energy source such as the sun is much more problematic. The winter months get darker the further one is from the equator. In some locations, the sun does not shine for extended periods of time. These are the periods with the coldest days, thus the electricity demand for heating is significant. Consequently, a solution based on solar energy must have a huge energy storage capacity.

Aluminum energy

Scientists at the SPF Institute of Solar Technology in Switzerland have set their sights on aluminum energy storage. One cubic meter of aluminum can store approximately 23.5 megawatt hours of energy, sufficient to power a home for 2.2 years. This storage capacity is at least fifty times that of a comparable-sized lithium-ion battery. However, huge blocks are difficult to manipulate, so they are now using metal balls instead.

The approach utilized by the scientists is known as an aluminum redox cycle, and its operation is as follows: Renewable energy can be utilized to transform aluminum oxide or aluminum hydroxide into elemental aluminum. This well-known electrolysis method demands a temperature of approximately 800 degrees. The outcome is “charged” aluminum.

Hydrogen and temperature

The greatest task is to release this energy again. The Swiss scientists see potential in a technology that converts pure aluminum into hydrogen for this purpose. When electrically charged aluminum is treated with water and a chemical compound, hydrogen and heat are produced. The hydrogen can be used for a variety of applications, and the captured heat can be used to heat homes directly. Scientists at the Massachusetts Institute of Technology (MIT) made news with their first successful trial just one year ago.

Infinite process

The beauty of an aluminum redox cycle is that the process can theoretically be performed indefinitely with the same quantity of aluminum. In addition, aluminum is more accessible than the rare earth metals that are now commonly used in battery production. The aluminum scrap was employed in the MIT investigation.

There are balls in the truck

If it were up to the scientists at the SPF Institute, a facility would be constructed in a sunny, central position to charge pure aluminum. These charged metal balls can then be transported by truck to energy-demanding locations. Once “empty,” the pellets are returned to the plant and refilled.

In the meanwhile, the Swiss scientists are supported by European funds and have assembled a team of nine organizations and seven European nations under the moniker Reveal. Unfortunately, we will not see a large-scale application very soon. Reveal plans to modify the design until at least 2026.

Nedim Husomanovic

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