The “solar cube” for drinking water

 Scientists create a solar cube to generates free, unlimited water from thin air 

A window cube will soon have the power to evaporate and condense water from the air into drinkable water and will thus transform the way we gain access to litres of water. This window cube was an innovation developed by an international research team. The idea behind this invention was to create a small wooden device which can harvest clean drinking water from the air without any pipes, electricity or other movable parts. This easy water solution is needed in a world where water scarcity impacts over 80% of the population. A practical solution is on offer which is powered by the sun and basic materials like wood and salt. Scientists create a solar cube which generates free drinking water from the air. Imagine a world where you don’t have to wait for rain to collect water. This water no longer needs to come from a pipe, but from the air itself. Although it may seem like a reference to the moisture farms in Star Wars, it is a simple but revolutionary invention which exists in the real world. A device has been created which could change everything in areas with low annual rainfall.

Researchers at the Royal Melbourne Institute of Technology (RMIT) and the Zhejiang A&F University were behind the big unveil of a water-harvesting device created solely from balsa wood, lithium chloride salt and carbon nanotube ink. While none of the materials utilized are special, the amalgamation of such simplistic materials has resulted in a working water generator which is portable and able to produce water from the air. More than 80% of the world’s population struggles with inadequate access to drinking water. Traditional solutions are expensive, as they rely on complex infrastructure or require enormous amounts of electricity and network maintenance. In real life, we need simple, centralized ways to access clean water. This is where the solar cube comes in. The cube is a small device developed by engineers. The simplicity of the solar cube is its greatest advantage: it has no moving parts, uses no electricity and requires no plumbing. It seems illogical that something so simple could convert moisture in the air into drinking water. But this little cube works by taking advantage of a completely natural cycle of absorption and release. It is a scientific theory applied to an incredibly ingenious design.

As per the process, delignified balsa wood becomes soft and spongy when its rigid component is removed. The result is a block of wood that is sponge-like and porous. This sponge-like block absorbs the environment’s moisture. This, along with the salt and lithium chloride, reacts with water molecules and becomes most effective at absorbing the water. The other cube side is coated with carbon nanotube ink, responsible for capturing solar energy and heating up rather rapidly. When the sun rises, the collected water evaporates within the cube and condenses into a liquid. The liquid is then ready to be collected. The entire system is genius and is 94% efficient. When we think of collecting moisture from the air, we often think of domestic or industrial dehumidifiers. These machines use compressors and a lot of electricity to cool the air to the dew point. The Solar Cube does the same job, but it is based on a chemical principle and the power of the sun. Instead of using electricity, it is passively powered by nature. It is based on the fundamental principle that the air around us is always saturated with water vapour. Although many moisture collection technologies failed miserably in dry locations, the Solar Cube continues to function in low-humidity environments, performing efficiently at levels as low as only 30% relative humidity. This makes it the perfect solution for arid and drought-stricken regions worldwide.

Simplicity is at the core of this innovation which performs well. During outdoor tests where the humidity was about 65.9%, the cube absorbed more or less 2,5 millilitres of water per gram overnight and released most of it when placed in the sun the following day. The cube is even functional in low-humidity environments where the humidity is around 30%. Weighing less than a gram, the cube is a portable solution. However, when many cubes are put together, the power which can be generated is immense. In fact, nine cubes together can absorb more or less 15 millilitres of water during the night. Therefore, the potential which will result from linking many cubes together cannot be overstated. The solar cube system is based on three very simple components. First is balsa wood, which acts as the structural base or scaffolding. Researchers remove the lignin, which is the compound which makes wood rigid. This creates a highly porous wood sponge, perfect for absorbing and retaining moisture. Then they introduce lithium chloride, which is the real water magnet. This salt is highly hygroscopic (meaning it attracts water very strongly), impregnating the wood sponge. It thus attracts and aggressively adheres to water vapour molecules in the air, even when the ambient humidity is very low. The third component is carbon nanotube ink, which functions as a solar heater. One side of the cube is covered with this specialized photo thermal layer. When it absorbs sunlight, it instantly converts light into heat. With these three components, the solar cube can create a zero-energy day-night cycle. At night, the cube is cold and charges with vapour from the atmosphere, like a passive trap. During the day, when the sun rises, the field of carbon nanotubes heats up quickly. This heat forces the water to evaporate again. The vapour is then channelled into a condenser, where it cools and returns to its liquid form as clean liquid water, ready for collection.

The cube can help considerably with providing drinking water. However, this solar-powered cube was created more so to provide emergency relief and to be used for agricultural purposes in secluded areas. With the cube, indoor humidity can be regulated as well. The cube will help best in regions which experience the problem of water scarcity. Dr. Junfeng Hou, who was a core part of the Chinese research team, said that scaling up the cubes or producing smaller cubes would be rather cost-effective. With cost burdens and environmental burdens eliminated, this is a great step towards a better water future. This is, however, not the first cube to result in drinking water from thin air. The solar cube system achieved a daily collection efficiency of 94% in outdoor tests. During these tests in real conditions, with 65% humidity, the prototype managed to collect 2.5 ml of water per gram of material during the night. As the water is collected from the atmosphere, it does not need to be boiled, since the water collection process involves a process similar to distillation. The water leaves behind virtually all bacteria, viruses, dissolved salts, heavy metals and contaminants which might have been suspended in the air. The result is ultra-pure water at the time of collection. For now, we will wait for the solar cube to begin commercial use in more rural areas.

The World Health Organization estimates that 2.2 billion people around the world still lack access to safe drinking water. This invention could provide hope for remote communities, disaster-hit areas and regions suffering from drought and climate change. Researchers say that if the device is made on a large scale, the cost could drop further, making it very affordable. Humanitarian groups are already planning to use it in Africa and the Middle East. Commercial production is expected to begin in the near future. Experts also think the device could be useful for the military, space missions and emergency situations where normal water supplies are not available.