Curious ElfWith climate change on the rise, our hot and crowded world is becoming a difficult place to live. We have already consumed most of the natural resources, polluted our natural water bodies, melted the glaciers, and murdered wildlife. To increase our problems, clean water is becoming a precious commodity. It can be said that inadequacy of clean water could lead to wars among countries.
According to a WWF report, it has been estimated that by 2025, two-thirds of the world population will face issues accessing fresh water. Now, Earth is 70% water. The only issue is it is all saltwater that we cannot consume. To slake humanity’s thirst in the future, we need to find ways to remove contaminants and salt from the oceans and groundwater.
While the installation of large distillation plants has been proposed, they are extremely expensive to build. Also, reverse osmosis is used by many plants to clean and filter water. Reverse osmosis forces saltwater through salt-blocking membranes to produce fresh water. Now, the electricity required to run the RO system accounts for up to half of the water treatment plant’s expenses. What’s worse is that the entire procedure leaves behind a chemical-laced, super-salty brine residue that can harm the local ecosystem if dumped directly. What makes it even worse is that such water treatment plants are powered by carbon-emitting fossil fuels.
Given that something urgent needs to be done in this case, researchers are trying to use the sun’s energy to make salty, contaminated water fresh and clean. Taking inspiration from nature, the idea is to let the water evaporate completely, leaving the salts and other contaminants behind, and then condense the water vapors into clean water. However, this also comes at a cost, as setting up huge plants with all the equipment put a dent in the government’s budget.
In Saudi Arabia, engineers and researchers are planning to build a water treatment plant with gigantic mirrors that concentrate the sun’s light and superheat the salty water stored within a large steel and glass dome spread across 50 meters. This is a concept and not a foolproof solution.
Researchers are trying to use novel designs and materials to make the process simpler, cheaper, and portable enough to make high-quality distillation and desalination accessible across the globe.
In developing countries, the need for fresh, clean water is ever increasing. Solar thermal technologies are considered to be a way out of this dilemma. This is because it allows you to lower the energy needs for water purification and also do it in a location where you are completely off the grid.
According to Qilin Li, an environmental engineer at Rice University, no technology today is able to handle high-salinity in the water at such low costs. Earlier, the US Department of Energy commenced a competition for solar desalination. The department will soon shortlist the semifinalists for the Solar Desalination Prize. The objective of the competition is to develop a system that can produce up to 1,000 liters of usable fresh water for a mere $1.50.
Such systems could overcome the issues and downsides of reverse osmosis. The most significant downside of RO technology is that it only desalinates half of the input saltwater. What’s left behind is a soup-like residue (brine) that is either dumped into the ocean or dug into the ground. This can create an ecological imbalance.
The use of solar power for desalination can filter and purify water with salt content at least twice that of ocean water. This would include brackish groundwater and brine from RO plants, as well as agricultural and industrial wastes that RO cannot handle. According to researchers, only thermally driven technologies and methods like solar desalination can process these highly saline brines.
Researchers at Rice University have developed a solar desalination system with a porous plastic membrane. This specially designed membrane lets water vapor in but not liquid. One side of the membrane is coated with tiny carbon particles that get heated up when come in contact with sunlight. As a result, the salty water that comes in contact with it becomes vaporized. The vapors pass through the membranes and condense as clean water.
This is just the start we needed in this field. We have to wait until a more robust system is developed.
