Tag Archives: desalination

Wired for water: How electrification is transforming desalination

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Pressure on the world’s water resources is rising steadily — and in many places, it is reaching critical levels. Growing populations, expanding cities, and increasing demand from agriculture and industry are all putting fresh water supplies under strain, particularly in regions that are already struggling.

To cope with this, many countries have turned to desalination — the process of converting seawater into usable fresh water. While this has helped ease shortages in some of the hardest-hit areas, it comes at a cost. Desalination can be energy-intensive, accounting for anything from a negligible share to as much as 15 per cent of a country’s total energy use, depending on how heavily it relies on the technology. Now, a shift is underway. Older, heat-based systems are gradually being replaced by electricity-driven methods, reflecting a broader transition in how energy is produced and used.

The scale of global water use highlights the challenge. Each year, more than 4,000 billion cubic metres of freshwater are withdrawn worldwide. Of this, nearly 1,500 billion cubic metres are consumed — meaning the water is not returned to its source. To put that into perspective, humanity uses roughly the equivalent of the entire volume of Lake Michigan every year.

Agriculture remains by far the largest consumer, accounting for around 70 per cent of total withdrawals and close to 90 per cent of actual consumption. As the global population has grown by about 30 per cent since 2000, water demand from cities has risen at a similar pace. A slight decline in industrial water use has done little to offset this broader increase.

The result is mounting water stress. In many regions, water is being extracted faster than it can be replenished, particularly from underground sources. Over time, this kind of overuse can permanently damage ecosystems and lead to what experts describe as “water bankruptcy” — a point at which natural reserves can no longer recover.

Over the past two decades, nearly one billion more people have come to live in areas facing high water stress, pushing the global total to over three billion. Much of this increase has occurred in regions already under severe strain. Today, about 30 per cent of the world’s population lives in areas classified as extremely water-stressed, with around 85 per cent of those affected residing in emerging and developing economies.

The situation is especially stark in fast-growing countries. In India, for instance, more than 70 per cent of the population lives in water-stressed regions. The scale of the problem is such that the number of people currently affected is roughly equal to the country’s entire population in the early 2000s.

The Middle East and North Africa face an even harsher reality. Home to around 490 million people as of 2024, the region has long grappled with limited water resources. About three-quarters of its population lived under water stress at the turn of the century, and despite some population shifts toward relatively less affected areas, more than 70 per cent still live in conditions of high or extreme water scarcity today.

Taken together, the trends point to a deepening global challenge. As demand continues to rise and climate pressures intensify, managing water resources — and the energy needed to sustain them — is becoming one of the defining issues of our time.

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Desalination: Making seawater drinkable in minutes possible now

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A research team in KICT, led by Dr. Yunchul Woo, has developed co-axial electrospun nanofiber membranes fabricated by an alternative nano-technology, which is electrospinning. This new desalination technology shows it has the potential to help solve the world’s freshwater shortage.
The developed technology can prevent wetting issues and also improve the long-term stability in membrane distillation process. A three-dimensional hierarchical structure should be formed by the nanofibers in the membranes for higher surface roughness and hence better hydrophobicity.
IMAGE: SCHEMATIC OF CO-AXIAL ELECTROSPINNING DEVICE. view more 

CREDIT: ELSEVIER

According to the World Health Organization, about 785 million people around the world lack a clean source of drinking water. Despite the vast amount of water on Earth, most of it is seawater and freshwater accounts for only about 2.5% of the total. One of the ways to provide clean drinking water is to desalinate seawater. The Korea Institute of Civil Engineering and Building Technology (KICT) has announced the development of a stable performance electrospun nanofiber membrane to turn seawater into drinking water by membrane distillation process.

Membrane wetting is the most challenging issue in membrane distillation. If a membrane exhibits wetting during membrane distillation operation, the membrane must be replaced. Progressive membrane wetting has been especially observed for long-term operations. If a membrane gets fully wetted, the membrane leads to inefficient membrane distillation performance, as the feed flow through the membrane leading to low-quality permeate.

The co-axial electrospinning technique is one of the most favorable and simple options to fabricate membranes with three-dimensional hierarchical structures. Dr. Woo’s research team used poly(vinylidene fluoride-co-hexafluoropropylene) as the core and silica aerogel mixed with a low concentration of the polymer as the sheath to produce a co-axial composite membrane and obtain a superhydrophobic membrane surface. In fact, silica aerogel exhibited a much lower thermal conductivity compared with that of conventional polymers, which led to increased water vapor flux during the membrane distillation process due to a reduction of conductive heat losses.

Most of the studies using electrospun nanofiber membranes in membrane distillation applications operated for less than 50 hours although they exhibited a high water vapor flux performance. On the contrary, Dr. Woo’s research team applied the membrane distillation process using the fabricated co-axial electrospun nanofiber membrane for 30 days, which is 1 month.

The co-axial electrospun nanofiber membrane performed a 99.99% salt rejection for 1 month. Based on the results, the membrane operated well without wetting and fouling issues, due to its low sliding angle and thermal conductivity properties. Temperature polarization is one of the significant drawbacks in membrane distillation. It can decrease water vapor flux performance during membrane distillation operation due to conductive heat losses. The membrane is suitable for long-term membrane distillation applications as it possesses several important characteristics such as, low sliding angle, low thermal conductivity, avoiding temperature polarization, and reduced wetting and fouling problems whilst maintaining super-saturated high water vapor flux performance.

Dr. Woo’s research team noted that it is more important to have a stable process than a high water vapor flux performance in a commercially available membrane distillation process. Dr. Woo said that “the co-axial electrospun nanofiber membrane have strong potential for the treatment of seawater solutions without suffering from wetting issues and may be the appropriate membrane for pilot-scale and real-scale membrane distillation applications.”