AUG 02, 2019 9:00 AM PDT

New Battery Tech "Squeezes" More Electricity out of Seawater

(Pixabay)

Ocean makes up 71% of the Earth's surface, and they also harbor one of the world's greatest yet almost untouched energy source: osmotic power. The salinity gradient where seawater and freshwater meet creates an osmotic pressure, which can be harnessed and turned into electricity. 

In a recent report, a group of environmental engineers at Stanford University announced that they have developed a new battery technology that converts salinity gradient differentials into electricity. Unlike some of the current designs, their battery uses economical electrode materials that can work repeatedly without energy-costing charge steps.

Also known as "blue energy", osmotic power was first turned into reality by Israeli engineer Sidney Loeb in the 1970s. Inspired by his observation of the Jordan River pouring into the extremely salty Dead Sea, Loeb invented a method to harvest osmotic power at freshwater outlets, based on the reversed-electrodialysis (RED) principle. Later on another salinity gradient-based mechanism-pressure retarded osmosis (PRO) was also developed and put into power-generating applications in laboratories. 

The world's first osmotic power station at Tofte, Norway (Bloomberg News)

Starting its electricity production in November 2009, Statkraft osmotic power station located at Tofte in Hurum, Norway is the first of its kind. Using the PRO mechanism, the Statkraft plant produced an output of 2-4 kilowatts (KW). With an improvement of its membranes, the plant can hypothetically put out 10 kW at maximum. 

The mixing entropy battery (MEB) developed by the Stanford group tackles a problem that's currently faced by all osmotic power generators. 

In theory, a minimum of 0.65 KW of electricity is lost (as a result of entropy increasing) when every cubic meter of freshwater that mixes with seawater. This loss of supposedly recoverable energy would have a significant impact on the scale-up of the current technologies. 

The Stanford scientists came up with a so-called mixing entropy battery (MEB). It uses Prussian Blue and polypyrrole, two inexpensive compounds as electrodes. MEB generates electricity through a four-step process: freshwater exchange, charging in freshwater, seawater exchange and discharging in seawater. 

As an improvement from the previous design, the charging of the electrodes now requires zero energy input, and the electrode materials demonstrated superb stability after hundreds of repeated cycles. Using the MEB, the researchers were able to recover about 68% (0.44 kW) of otherwise lost energy, as demonstrated in their experiments. 

In a press release, Kristian Dubrawski, coauthor of the paper and a postdoctor at Stanford's Civil and Environmental Engineering commented on their design: “It is a scientifically elegant solution to a complex problem. It needs to be tested at scale, and it doesn’t address the challenge of tapping blue energy at the global scale—rivers running into the ocean—but it is a good starting point that could spur these advances.”

According to the authors, they hope to scale up their prototype and still achieve similar recovery efficiency. The full-size MEB is expected to be able to power up a conventional wastewater treatment plant, often located at the mixing points of seawater and freshwater.

This study was published in the journal ACS Omega.

Interested in learning more about osmotic power-generating technologies? Check out this video below:

Blue Energy- Salinity gradient power (ACCIONA)

Source: ZME Science

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
OCT 10, 2019
Cell & Molecular Biology
OCT 10, 2019
Light Therapy Developed for Treating Carbon Monoxide Poisoning
According to the Centers for Disease Control and Prevention, everyone is at risk from carbon monoxide (CO) poisoning....
OCT 14, 2019
Cell & Molecular Biology
OCT 14, 2019
Understanding How Life Could Have Arisen From RNA
Around 4 billion years ago, scientists think that life arose, and they have been trying to learn more about how that happened...
OCT 16, 2019
Chemistry & Physics
OCT 16, 2019
Outlandish Ideas to Fight Climate Change: How Credible are They?
Boosting investment in renewable energy and reducing the use of fossil fuel are the two commonly acceptable measures to combat climate change. However, sci...
OCT 21, 2019
Space & Astronomy
OCT 21, 2019
Here's Why NASA Wants to Crash a Spacecraft Into an Asteroid
Yes, you read that right; NASA would like to slam a purposefully built spacecraft into the surface of an asteroid. While this idea might seem like a substa...
DEC 22, 2019
Space & Astronomy
DEC 22, 2019
How Astronomers Measure Distances to Stars
Extra stellar systems are so far away from our own that we couldn’t even hope of developing a tape measure long enough to determine how far away they...
JAN 13, 2020
Chemistry & Physics
JAN 13, 2020
Magnetic Field-guided Tethered-probe Can Navigate Complex Vascular Networks
Deep and complex vasculatures such as carotid arteries represent a challenge for diagnosis and treatment because they are buried underneath layers of other...
Loading Comments...