Compact solar-powered reactor for easy hydrogen production developed

The module presented by the Fraunhofer Institute is the all-in-one solution for hydrogen production. The complete system can split water into hydrogen and oxygen using only electricity, which it generates itself.

This element for the direct solar splitting of water is called a photoelectrochemical cell, or PEC for short. This turns the small device into a tandem PEC module. It is intended to be used to generate hydrogen for further use as flexibly as possible and without extensive set-up.

However, the development up to this point was not entirely straightforward. Hydrogen is not only very volatile. If it mixes with the oxygen that is also produced after generation, a so-called detonating gas reaction can occur. The name says it all.

Two strictly separate areas must therefore exist within the tandem cell. This works with a glass pane that is coated on both sides with two different semiconducting materials. The upper layer only absorbs short-wave light. The lower side converts the long-wave light into electricity.

This allows hydrogen to be produced at the bottom and oxygen at the top. The hydrogen is captured and can then be stored, even if this is a complex process.

As a complete solution, all that remains is for the sun to shine, water to be available and production to start. According to the Fraunhofer Institute, field tests have already been carried out on a large scale.

The Central European sun, i.e. very little sunlight, is sufficient to produce 150 grams of pure hydrogen per year from a single tandem PEC module with an active area of half a square meter (5 sq. ft.). With 100 square meters (1,000 sq. ft.), the result would be 30 kilograms (66 lbs). This would give a hydrogen vehicle a range of 3,000 kilometers (2,000 miles).

However, some work still needs to be done on efficiency. If you only look at the energy that can be generated, a commercial solar cell can generate 20 times as much in the same amount of sunlight. However, the principle of obtaining hydrogen directly from a single element is definitely worth further efforts until the efficiency reaches practicable values.