Desalination on the Cheap for the Masses

ocean shore
Water water everywhere and plenty of drops to drink. Researchers from MIT have found a way to passively convert seawater into drinking water using a setup so simple it seems too good to be true. Their device basically uses heat from the sun rays and a siphon. The apparatus produces more water and rejects more salt than other passive setups, it can generate five litres of water if the device is one square meter in size. All of this with no external energy. They have even tested the device in open water – and it works! Imagine hundreds of these devices floating on the ocean bringing drinking water to cities.

The heart of the team’s new design is a single stage that resembles a thin box, topped with a dark material that efficiently absorbs the heat of the sun. Inside, the box is separated into a top and bottom section. Water can flow through the top half, where the ceiling is lined with an evaporator layer that uses the sun’s heat to warm up and evaporate any water in direct contact. The water vapor is then funneled to the bottom half of the box, where a condensing layer air-cools the vapor into salt-free, drinkable liquid. The researchers set the entire box at a tilt within a larger, empty vessel, then attached a tube from the top half of the box down through the bottom of the vessel, and floated the vessel in saltwater.

In this configuration, water can naturally push up through the tube and into the box, where the tilt of the box, combined with the thermal energy from the sun, induces the water to swirl as it flows through. The small eddies help to bring water in contact with the upper evaporating layer while keeping salt circulating, rather than settling and clogging.

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Cities can Easily Reducing Salt Wasted on Roads

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Transportation systems that put cars front and centre cause a lot of damage, we know this. But aspects of our cultural approach to getting around like, the reliance on road salt, are easily ignored. Every winter in North America we dump an unfathomable amount of salt on our roads which subsequently kills off wildlife. The costs of using road salt are high.

Cities are waking up to the damage years of salting their roads have done not only to local ecosystems but also to their budgets. Using road salt isn’t cheap and now cities are looking to alternatives, or at the very least, strategies to reduce the amount of salt they put on roads.

Area officials found that, pound for pound, brine was far more efficient than traditional rock salt. They could protect a lane-mile of road with a solution containing under 100 pounds of salt, roughly one third the amount used by rock-salt trucks.

Last, the towns switched to live-edge plows, which have flexible blades made up of multiple, independently moving sections mounted on springs. These state-of-the-art blades are more thorough than conventional ones. And starting with brine makes the plows even more efficient, says Eric Siy, executive director of The FUND for Lake George. If live-edge snowplows are like razors that hug the curves, brine is like shaving cream.

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The Salt for the People

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For the region of Uttar Pradesh anemia is a big problem and the solution is to be salted. At the University of Toronto they have developed a new kind of salt that has been proven to reduce amen rates and improve the health of the population. Called double-fortified salt the new kind of salt is iron rich which took 20 years of research to create. It’s been proven to work in India so maybe it can work in other parts the world too.

Diosady began testing the efficacy of his creation during a pilot project in 2004 in the Indian state of Tamil Nadu, where the government supplies impoverished school children with one hot meal each day.

Regular salt was replaced with double-fortified salt in the lunches of more than three million children, 85 per cent of whom were anemic.

“In eight months, we cured a million kids from anemia,” Diosady said. “At the end, only 50 per cent were anemic.”

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Beets for Road Ice Removal

The traditional approach to deicing roads is to cover the roads (and thus the ground around the road) in salt – which is absolutely awful for the environment. Because so many people drive cars the demand for road salt is high and has come to negatively impact local economies and environments.

There is a solution to make salting less damaging and it’s already being used in some communities.

Beets are usually just used to create sugar or, like at Schrute Farms, beet soup. In Ontario roadworks departments have been using a byproduct from beet sugar processing to clear ice off of roads. They mix the beet byproduct with salt to create a new brine that works better and harms less.

Niagara Region has used the mixture for about three years, resulting in a 30 per cent reduction in road salt which damages tender fruit trees and vines, said Dave MacLeod, the region’s manager of transportation operations and technology.
The Ontario transportation ministry is working with Oakville and Grey County to test the effectiveness of other beet juice-based products that are added to brine, said a ministry spokesman.
“The ministry’s objective is to provide safe highways for all travellers by using the best available technology. At the same time, we recognize our responsibility to protect the environment, so we use technology to help us determine the best way to clear our highways in the most environmentally friendly, cost-effective way,” he said.

Read more at The Star.

Solar Power with Salt

Thermal solar power plants uses energy from the sun to heat up water and then run the resulting steam to power turbines. Simple enough, but now Siemens is looking to make that whole process more efficient by using salt.

Solar thermal power plants that produce hotter steam can capture more solar energy. That’s why Siemens is exploring an upgrade for solar thermal technology to push its temperature limit 160 °C higher than current designs. The idea is to expand the use of molten salts, which many plants already use to store extra heat. If the idea proves viable, it will boost the plants’ steam temperature up to 540 °C—the maximum temperature that steam turbines can take.

Siemens’s new solar thermal plant design, like all large solar thermal power plants now operating, captures solar heat via trough-shaped rows of parabolic mirrors that focus sunlight on steel collector tubes. The design’s Achilles’ heel is the synthetic oil that flows through the tubes and conveys captured heat to the plants’ centralized generators: the synthetic oil breaks down above 390 °C, capping the plants’ design temperature.

Startups such as BrightSource, eSolar, and SolarReserve propose to evade synthetic oil’s temperature cap by building so-called power tower plants, which use fields of mirrors to focus sunlight on a central tower. But Siemens hopes to upgrade the trough design, swapping in heat-stable molten salt to collect heat from the troughs. The resulting design should not only be more efficient than today’s existing trough-based plants, but also cheaper to build. “A logical next step is to just replace the oil with salt,” says Peter Mürau, Siemens’s molten salt technology program manager.

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