#battery technology

Scientists have developed a new solar-powered system to convert saltwater into fresh drinking water which they say could help reduce dangerous the risk of waterborne diseases like cholera.

Via tests in rural communities, they showed that the process is more than 20% cheaper than traditional methods and can be deployed in rural locations around the globe.

Building on existing processes that convert saline groundwater to freshwater, the researchers from King’s College London, in collaboration with MIT and the Helmholtz Institute for Renewable Energy Systems, created a new system that produced consistent levels of water using solar power, and reported it in a paper published recently in Nature Water.

It works through a process called electrodialysis which separates the salt using a set of specialized membranes that channel salt ions into a stream of brine, leaving the water fresh and drinkable. By flexibly adjusting the voltage and the rate at which salt water flowed through the system, the researchers developed a system that adjusts to variable sunshine while not compromising on the amount of fresh drinking water produced.

Using data first gathered in the village of Chelleru near Hyderabad in India, and then recreating these conditions of the village in New Mexico, the team successfully converted up to 10 cubic meters, or several bathtubs worth of fresh drinking water. This was enough for 3,000 people a day with the process continuing to run regardless of variable solar power caused by cloud coverage and rain.

[Note: Not sure what metric they're using to calculate daily water needs here. Presumably this is drinking water only.]

Dr. Wei He from the Department of Engineering at King’s College London believes the new technology could bring massive benefits to rural communities, not only increasing the supply of drinking water but also bringing health benefits.

“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,” said He.

“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.”

In the global rural population, 1.6 billion people face water scarcity, many of whom are reliant on stressed reserves of groundwater lying beneath the Earth’s surface.

However, worldwide 56% of groundwater is saline and unsuitable for consumption. This issue is particularly prevalent in India, where 60% of the land harbors undrinkable saline water. Consequently, there is a pressing need for efficient desalination methods to create fresh drinking water cheaply, and at scale.

Traditional desalination technology has relied either on costly batteries in off-grid systems or a grid system to supply the energy necessary to remove salt from the water. In developing countries’ rural areas, however, grid infrastructure can be unreliable and is largely reliant on fossil fuels...

“By removing the need for a grid system entirely and cutting reliance on battery tech by 92%, our system can provide reliable access to safe drinking water, entirely emission-free, onsite, and at a discount of roughly 22% to the people who need it compared to traditional methods,” He said.

The system also has the potential to be used outside of developing areas, particularly in agriculture where climate change is leading to unstable reserves of fresh water for irrigation.

The team plans to scale up the availability of the technology across India through collaboration with local partners. Beyond this, a team from MIT also plans to create a start-up to commercialize and fund the technology.

“While the US and UK have more stable, diversified grids than most countries, they still rely on fossil fuels. By removing fossil fuels from the equation for energy-hungry sectors like agriculture, we can help accelerate the transition to Net Zero,” He said.

Excerpt from this story from NPR:

When a group of engineers and researchers gathered in a warehouse in Mukilteo, Wash., 10 years ago, they knew they were onto something big. They scrounged up tables and chairs, cleared out space in the parking lot for experiments and got to work.

They were building a battery — a vanadium redox flow battery — based on a design created by two dozen U.S. scientists at a government lab. The batteries were about the size of a refrigerator, held enough energy to power a house, and could be used for decades. The engineers pictured people plunking them down next to their air conditioners, attaching solar panels to them, and everyone living happily ever after off the grid.

The idea for this vanadium redox battery began in the basement of a government lab, three hours southeast of Seattle, called Pacific Northwest National Laboratory. It was 2006, and more than two dozen scientists began to suspect that a special mix of acid and electrolyte could hold unusual amounts of energy without degrading. They turned out to be right.

It took six years and more than 15 million taxpayer dollars for the scientists to uncover what they believed was the perfect vanadium battery recipe. Others had made similar batteries with vanadium, but this mix was twice as powerful and did not appear to degrade the way cellphone batteries or even car batteries do. The researchers found the batteries capable of charging and recharging for as long as 30 years.

"It was beyond promise," said Chris Howard, one of the engineers who worked there for a U.S. company called UniEnergy. "We were seeing it functioning as designed, as expected."

But that's not what happened. Instead of the batteries becoming the next great American success story, the warehouse is now shuttered and empty. All the employees who worked there were laid off. And more than 5,200 miles away, a Chinese company is hard at work making the batteries in Dalian, China.

The Chinese company didn't steal this technology. It was given to them — by the U.S. Department of Energy. First in 2017, as part of a sublicense, and later, in 2021, as part of a license transfer. An investigation by NPR and the Northwest News Network found the federal agency allowed the technology and jobs to move overseas, violating its own licensing rules while failing to intervene on behalf of U.S. workers in multiple instances.

Now, China has forged ahead, investing millions into the cutting-edge green technology that was supposed to help keep the U.S. and its economy out front.

Department of Energy officials declined NPR's request for an interview to explain how the technology that cost U.S. taxpayers millions of dollars ended up in China. After NPR sent department officials written questions outlining the timeline of events, the federal agency terminated the license with the Chinese company, Dalian Rongke Power Co. Ltd.

"DOE takes America's manufacturing obligations within its contracts extremely seriously," the department said in a written statement. "If DOE determines that a contractor who owns a DOE-funded patent or downstream licensee is in violation of its U.S. manufacturing obligations, DOE will explore all legal remedies."

The department is now conducting an internal review of the licensing of vanadium battery technology and whether this license — and others — have violated U.S. manufacturing requirements, the statement said.

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The world's largest flow battery has started operation in Dalian, China with a capacity of 100 MW/400 MWh, and is designed to help the city handle its solar/wind intermittency with longer term grid storage ability than lithium-ion batteries.