New Solar-Powered System Transforms Saltwater Into Clean, Affordable Drinking Water

Scientists have developed a solar-powered technology that converts saltwater into clean drinking water free of dangerous waterborne diseases. If their claims are true, then this may represent a massive step towards providing reliable and safe water to developing countries and others.

Access to clean water is something we take for granted in the developed world. Most of us barely think about whether the water flowing from our taps, water that appears nearly instantly, is safe or not. However, this is not the case for everyone. In fact, around 40 percent of the global population does not have access to sufficient clean water. Worse still, UN-Water estimates that around 4 billion people experience severe water scarcity for at least one month of the year. And, with the growing climate crisis, this issue is only going to get worse.

As such, the need for new methods to provide clean, reliable water to at risk countries and regions continues to grow. But the latest research from King’s College London may offer some measure of hope in this effort.

The team, working in collaboration with MIT and the Helmhotz Institute for Renewable Energy Systems, has created a new system that produces consistent levels of water using solar power. According to their new study, the process is more than 20 percent cheaper than traditional methods and can be used in rural locations across the world. This is quite a powerful claim and sounds like an act of modern alchemy.

“This technology can expand water sources available to communities beyond traditional ones,” Dr Wei He, Senior Lecturer in Engineering at King’s College London said in a statement, “and by providing water from uncontaminated saline sources, may help combat water scarcity or unexpected emergencies when conventional water supplies are disrupted, for example like the recent cholera outbreaks in Zambia.”

So how does it work? The new system uses specialized membranes to channel salt ions into a stream of brine. This can then be separated from the water, leaving it fresh and drinkable.

What’s more, the team have developed a way to flexibly adjust the voltage and rate at which saltwater flows through the system. This allowed them to adjust for whatever sunlight is available while not compromising the overall amount of drinking water it produced.

The team initially gathered information in the village of Chelleru, near Hyderabad, India. They then used this information to recreate the same conditions in a village in New Mexico, where they successfully converted up to 10 cubic meters (353 cubic feet) of fresh water – enough to provide for 3,000 people a day. The process continued regardless of whether the Sun was obscured by clouds or rain.

“By offering a cheap, eco-friendly alternative that can be operated off the grid, our technology enables communities to tap into alternative water sources (such as deep aquifers or saline water) to address water scarcity and contamination in traditional water supplies,” He added.

“This technology can expand water sources available to communities beyond traditional ones and by providing water from uncontaminated saline sources, may help combat water scarcity or unexpected emergencies when conventional water supplies are disrupted, for example like the recent cholera outbreaks in Zambia.”

Across the world, around 56 percent of the available groundwater is saline and unsuitable for drinking. This issue is particularly severe in places like India where 60 percent of the land contains saline water. So this new system offers hope for efforts to desalinate water sources safely and affordably.

Most desalination technologies use expensive batteries in off-grid systems or use a lot of energy through grid systems to remove salt content from water. This is expensive and unreliable, especially in rural areas in developing countries. Here, fossil fuels are often used to power generators, which are damaging for the environment.

This new low-cost system, which is “battery-like”, offers new and sustainable ways to desalinate water which takes the pressure off individual consumers to maintain.

He added: “Traditionally, desalinating water has been energy-intensive and costly, confining its use to areas with stable power and financial resources. By removing the need for a grid system entirely and cutting reliance on battery tech by 92 percent, our system can provide reliable access to safe drinking water, entirely emission free onsite and at a discount of roughly 22 percent to the people who need it compared to traditional methods.”

Outside of developing areas, the new system could help compensate for future issues posed by climate change, especially for agriculture. Although the aim should be to limit the effects of climate change all together, the ability to produce clean fresh water from saline water could help with irrigation.

“Fresh water for irrigation is a large problem in across the globe, including North America, the Middle East, and Sub-Saharan Africa,” He explained. “Drought and cost are major draws on an industry which relies on unstable reserves of water to survive, and climate change will further exacerbate these challenges.”

“By providing a sustainable way for farmers to produce freshwater for irrigation at a cut price without its volume being compromised, we can help them reduce costs, mitigate carbon emissions, and ensure agriculture production and eventually pass those benefits onto consumers.”

Places like the UK and the US have more stable and diversified grids than most other countries, but they still rely on fossil fuels to power them. As such, the new desalination system could help remove the need to rely on these fuels and may contribute to our efforts to achieve Net Zero.

“The next step for us is to apply this low-cost technology to other sectors, including wastewater treatment, and producing alkaline to make the ocean more alkaline to help it absorb more CO2 from the atmosphere,” He concluded. “By taking this approach not only can we decarbonise agriculture, but wider environmental and climate benefits as well.”

The paper is published in Nature Water.

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