Solar-powered oven makes fresh water from sea water
by   /  September 9, 2012

Sometimes the simplest ideas are the best. Concerned about the lack of fresh water in the developing world, designer Gabriele Diamanti wanted a solution to desalinate water that was available to households rather than relying on giant, centralized plants. He also wanted it to be something inexpensive that could be made by local craftsman. The result is a ceramic solar still called the Eliodomestico that operates like an “upside-down coffee percolator”.

The open-source design of the Eliodomestico is remarkably simple. It consists of two ceramic pieces that sit one atop the other. Inside the top piece is a black container into which salt water is poured. The sun heats the container, turning the water to steam. As pressure builds, the steam is forced down a tube into a container in the lower piece. There it condenses against the lid and collects in the basin of the container. The Eliodomestico collects about five liters (1.09 gal) of fresh water per day and costs about US$50 to build with no operating costs. The bottom container’s basin is designed to be transported on the head, which is a common practice in developing countries.

Nano Water Chip Could Make Desalination Affordable for Everyone
by   /  04/10/14

With freshwater declining throughout the globe, desalination looks increasingly attractive, but current technologies are expensive, demand far too much energy and are prone to contamination. Now researchers from the University of Texas at Austin and the University of Marburg in Germany have developed a “water chip” that creates a small electrical field that separates salt from seawater. The technology, which is still under development and works at the nano scale, uses so little energy it can run off a store-bought battery.

The researchers apply a 3.0 volt electrical charge to the plastic water chip, which has a microchannel with two branches. By creating an “ion depletion zone” with an embedded electrode that neutralizes chloride ions, they are able to redirect the salts in the water down one channel, while the fresh water goes down another. “Like a troll at the foot of the bridge, the ion depletion zone prevents salt from passing through, resulting in the production of freshwater,” the team wrote in a recent press release. Less energy-intensive than current desalination plants, the water chip doesn’t rely on a membrane, and can be made portable so that just about anybody living near the sea can purify their own water at home.

Currently the technology purifies just one nanoliter at a time and only has a 25% efficiency rate, but the team is confident that their proof of concept can be first improved and then scaled up. A small startup called Okeanos Technologies has been created to continue developing the technology. Its head, Tony Frudakis, said in the statement that people are dying for want of freshwater, and they will persevere to prevent that from happening. “You could build a disaster relief array or a municipal-scale unit,” said Frudakis. “Okeanos has even contemplated building a small system that would look like a Coke machine and would operate in a standalone fashion to produce enough water for a small village.”

by Rasha Dewedar  /  02/09/15

“Researchers at Alexandria University in Egypt have unveiled a cost-effective desalination technology which can filter highly salty water in minutes. The technology is based on membranes containing cellulose acetate powder, produced in Egypt. The powder, in combination with other components, binds the salt particles as they pass through, making the technique useful for desalinating seawater. “The membrane we fabricated can easily be made in any laboratory using cheap ingredients, which makes it an excellent option for developing countries,” says Ahmed El-Shafei, an associate professor of agricultural and biosystems engineering in Alexandria University, and an author of the study. The technology uses pervaporation, a technique by which the water is first filtered through the membrane to remove larger particles and then heated until it vaporises. The vapour is then condensed to get rid of small impurities, and clean water is collected. According to the research paper, published in Water Science and Technology last month, this method can be used to desalinate water which contains different types of contamination, such as salt, sewage and dirt. This kind of water is difficult to clean quickly using existing procedures.

“The undisputed champion of saltwater living, mangrove trees perch on their roots directly in the salty coastal ebb and flow. Some are so good at getting rid of salt you can drink their root-water.” – http://inhabitat.com/the-biomimicry-manual-how-does-nature-make-saltwater-drinkable/

The membrane technology in combination with vaporisation can be applied in remote settings, as it requires only the membranes for the filtering process, and fire to vaporise the filtered water, the researchers say. “Using pervaporation eliminates the need for electricity that is used in classic desalination processes, thus cutting costs significantly,” says El-Shafei. Pervaporation is used to separate organic liquids, like alcohols, and is one of the more common systems used in sewage treatment to separate water from organic solvents. The technology has been around since the mid-90s, Helmy El-Zanfaly, a professor of water contamination at Egypt’s National Research Center. But, he says, “What is new is making the membrane locally, using materials abundant in Egypt and developing countries.” El-Zanfaly adds that existing pervaporation membranes are fabricated using complicated procedures, making them unsuitable for cheap production. “The technology implemented in the study is much better than reverse osmosis, the technology currently used in Egypt and most of the countries in the Middle East and North Africa,” El-Zanfaly says. “It can effectively desalinate water with high concentration of salt like that of the Red Sea, where desalination costs more and yields less.” The technology can be adapted for commercial use by fabricating larger sheets of the membrane and cutting these into suitable swathes, according to El-Shafei. The next step for the team is to establish a small desalination unit as a pilot project for the technology.


Philippine startup lights up poor homes with lamp powered by salt and water
by Judith Balea  /  Nov 13, 2014

A possible power shortage coming in the summer of 2015 has been grabbing the headlines in the Philippines this year. But this is not news for millions of poor Filipino families off-grid: they have been living without electricity. For them, life stops after dark. They close stores early and make sure to be home before sunset. The night is just for sleeping. Lighting up their homes takes a lot of effort. They need to cut wood to create fire, or walk long hours to the nearest town to buy fuel for their lamps. Aisa Mijeno witnessed this first hand when she lived with the Butbut tribe in Buscalan, Kalinga during an immersion in 2011. “People did not have access to electricity and had to walk 12 hours to reach Bontoc, a town about 50 kilometres away, to get kerosene for their fuel-based lamps,” she shares in an interview with Tech in Asia. Mijeno, an engineer who has engaged in social work, says her experience in Kalinga became her motivation in creating an alternative lighting system that many wouldn’t even think possible. The lighting system doesn’t require electricity, batteries or even fuel to run. All it needs are two basic and natural things: salt and water.

SALt’s lamp looks nothing extraordinary – it makes use of a LED bulb – but you don’t need to plug it or use battery or fuel to make it light up. Dissolve two tablespoons of salt in a glass of water and pour it onto the lamp and voila, you have light for eight hours. Of course, it’s easier if you live by the sea since saltwater is readily available. The lamp gives out about 90 lumens equivalent to seven candles lit up or the brightness of a low-LED bulb. Meanwhile, it has a special feature: a USB slot for charging your mobile phone. Take note however that it can only perform one function at a time – so you need to choose between lighting it up or charging your device. The product is not rocket science, says Mijeno. In fact, the whole idea behind it is taught in high school chemistry classes. “If you did the lemon-battery experiment, that’s basically it. Two different metals submerged in electrolytes will produce electricity. For us, we used saltwater.”

“It is an open science… so I will not be surprised if there are existing similar technologies developed out there,” she adds. What’s surprising, according to her, is that “no one ever focused on making this a concrete system to harness energy.” After all, she explains, “Seventy percent of the earth’s surface is saltwater and we still rely on other expensive means that are dependent on geography, climate, and fuel.” SALt’s product addresses an overwhelming need. In the Philippines alone, 16 million families are off-grid, Mijeno notes, citing a 2013 study done by the Philippine Institute for Development Studies. She says their product will keep families from turning to substitutes that are dangerous and expensive like kerosene, which is a major contributor to indoor air pollution. Not only that – it will make a big difference in their lives. It will make them feel safe, give them more hours to spend on their livelihood, and allow their children to study at night.

Mijeno recognizes that many innovators don’t see the poor as a viable market that’s why social enterprises are rare. “There is a certain degree of difficulty when it comes to achieving financials enough to sustain and to scale a social enterprise and/or a hardware startup,” she says. She says in her case, pricing is especially tricky. “It is very difficult to find a middle point wherein we feel that we are not selling it for too much and also not underselling it.” Their lamp now costs US$35 (PHP1,570) – which is quite high for a poor family who often must prioritize food over anything else. So Mijeno says they’re improving the functionality and overall design of the lamp to make sure it “stands the test of time.” The lamp has a shelf life of 10 to 11 years depending on the LED bulb, and they want to extend this further by making it water- and shock-proof. They are also optimizing it to produce up to 350 lumens. “Considering its use, the initial price of the lamp trumps the sustaining cost of battery and fuel-based lighting.”