Saltwater Batteries: A New Wave in Renewable Storage

While seawater is already harnessed for drinking water via desalination and power generation through tides and wave motion, few people are aware that it could also serve as a key ingredient in next-generation energy storage. Researchers are now focusing on saltwater-based aqueous batteries—a solution that could bring large-scale, sustainable energy storage within reach.

This article explores:

• What aqueous batteries are and how they work

• A new anode design that could unlock their potential

• How they fit alongside other storage solutions like mega-batteries

What are aqueous batteries?

Aqueous batteries are energy storage systems that use water-based electrolytes instead of the flammable organic solvents found in conventional lithium-ion batteries. This makes them inherently safer, eliminating the risk of fire or explosion. Their water-based chemistry also improves sustainability and recyclability by reducing reliance on critical raw materials like lithium and cobalt.

These batteries store and release energy by moving ions between the anode and cathode through the aqueous electrolyte. Early results show they can deliver far greater energy densities—up to 10 times more in some cases—depending on the specific electrolyte formulation. However, technical challenges remain before this technology can be scaled for widespread deployment.

An anode to unlock scalability

Aqueous batteries offer a safer, more affordable, and more environmentally friendly alternative to lithium-ion technology. Yet their development has long been held back by the lack of a suitable anode material—the component where electrons exit the battery during discharge.

That may be changing, thanks to a team led by Professor Xiaolei Wang at the University of Alberta. The researchers have developed a robust universal anode for use in both aqueous and seawater-based batteries. This new anode, made from polymer nanolayers and carbon nanotubes, is capable of storing a wide range of ions—including those naturally occurring in seawater.

The design opens up new possibilities for applications ranging from battery storage to supercapacitors. It is also built to withstand harsh conditions, such as fast charge–discharge cycles and sub-zero temperatures. Perhaps most notably, the anode enables a cycle life of up to 380,000 charges—far surpassing the sub-10,000 cycle lifespan of most commercial batteries.

 

 

Mega-batteries for grid-scale renewable storage

Among the various technologies being explored for large-scale renewable energy storage—such as gravity-based systems, compressed air, or sand batteries—mega-batteries have emerged as one of the most commercially mature options.

These massive stationary energy storage systems, known as Battery Energy Storage Systems (BESS), are capable of storing surplus electricity generated during low-demand periods and releasing it back into the grid when demand spikes. This ensures grid reliability and helps balance intermittent supply from renewables. A notable example is the Cunningham battery storage facility in the US, currently operated by Acciona Energía.

Mega-batteries are critical to maintaining grid stability. They provide services such as backup power, frequency and voltage regulation, and reserve capacity, making it easier to integrate variable renewables like wind and solar.

With advanced concepts like aqueous batteries on the horizon, and proven technologies like BESS already in operation, the shift toward a fully renewable energy system—capable of serving both industry and households around the clock—looks increasingly within reach.

 

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• TechXplore