Collect fresh water from the sea with sunlight

Experts from the Institute of Chemistry (Vietnam Academy of Science and Technology) are deploying the application of new technologies: storing seawater by solar energy to get fresh water.

Two test equipment systems have been installed in Ben Tre. One system was located at Binh Dai fishing ground in late August 2005, providing 120-150 liters of clean water per day for the 8-person team. The other, smaller, system is expensive in a household in Ben Tre town.

Experts are installing solar water distillation equipment in Binh Dai and Ben Tre fishing grounds.Although it drilled to a depth of 400m, there was no fresh water found here.If installing reverse osmosis filtration system, it must cost several hundred million dong, not suitable for people living scattered.

The advantage of this technology is low investment costs, ease of use, clean water for residents in remote areas, scarcity of fresh water, dispersal and no electricity.

The technology is based on the principle of evaporating seawater to collect fresh water.

Seawater is put into tanks. Above the tank is covered with transparent glass roof to catch the sun. The sun causes salt water inside to heat up and evaporate. The steam rises to meet the bottom surface of the glass roof that will condense into droplets, flowing into the container. As a result, water is cleaner than rainwater because it is not contaminated with dust from the atmosphere.

However, the efficiency of the above method is usually low, only 2-3 liters / day per square meter because the sunshine time in the day is usually only 6-9 hours. On the basis of researching the technology of storing heat by phase conversion materials for nearly 10 years, the research group of Dr. Nguyen Tien Tai, Inorganic Materials Department, decided to apply this technology to increase the efficiency of the regulation. Seawater storage.

Dr. Tai revealed materials that store heat according to the phase transition mechanism used by the group as an available and cheap compound in Vietnam, derived from petroleum products. In this case, phase shift means that when the material receives heat, it softens and when heated, hardens.

The modern system in Binh Dai consists of 3 modules, each module has a useful capacity of 4m2.

Placed in a water storage device, the material will store excess heat from the daylight. When the sun is turned off, the material will release the stored heat to extend the distillation process.

In this way, the group obtained 8-10 liters / day per square meter. Currently, the group continues to improve the technology to increase the efficiency to 15-20 liters / m2 / day. The group also plans to add some micronutrients to the water after filtering because distilled water in this way is often too clean.

In March, the technology will be tested in Thua Thien-Hue.

After finishing, the team will transfer technology to mass production for localities such as islands and other freshwater scarcity.

The group's expectation is to reduce the price to 1 million VND / m2 when put into mass application.

Minh Son