Build a saltwater battery

Commercial Battery

Some manufacturers specialize in the production of these environmentally friendly energy storage systems. BlueSky Energy [8], for example, has a product – the Greenrock system – for both private and industrial use in its portfolio.

The storage systems are intended for stationary use only and are ideal for storing the energy generated by solar systems for personal consumption. As Figure 4 shows, a saltwater battery can certainly compete with the other electric storage systems on the market. In only two categories does it perform worse than a lithium-ion battery: energy density and C rating, which indicates how quickly the energy can be retrieved.

Figure 4: When comparing electricity storage systems, saltwater batteries perform quite well.

The energy density is not as good as that of lithium-ion batteries but is still as good as that of a lead-acid battery. Because of the lower energy density, the batteries are larger and heavier than lithium-ion batteries with the same capacity, but this is not really a problem when used indoors in a stationary environment.

With respect to the C rating, the saltwater battery turns out to be more of a marathon runner: It delivers a constant amount of energy over a long period of time, which is the application scenario in domestic use; however, it is not suitable for delivering high currents for short periods of time.

Saltwater batteries have several advantages over lithium-ion batteries. Apart from environmental friendliness and low fire hazard, the availability of resources plays a major role.

Discussions about electric vehicles have revealed that lithium mining causes considerable environmental damage. Recycling it is certainly a good idea, but it requires large amounts of energy and is expensive. Saltwater batteries fare far better in this respect; they cause virtually no environmental damage and are easy to recycle. The components of the saltwater battery exist on Earth in large quantities, whereas lithium does not.

A really serious issue that speaks against the use of lithium-ion batteries in buildings is their combustibility. You can find a number of YouTube videos that show the kind of fireworks that burning batteries of this type can cause. A saltwater battery, on the other hand, remains unfazed, even after prolonged exposure to heat [9].


The simple test setup in this article demonstrates that an energy storage device can be built with the simplest household objects. The Raspberry Pi helped keep the charging and discharging cycles the same and measured the charge. Although this scenario was merely an experimental setup that cannot be used in production, it works, and it can be modified for further experiments. One interesting question would be, for example, what level of self-discharge occurs.

Saltwater batteries have long been a mature and usable technology. They are well suited as energy storage for photovoltaic systems and, in contrast to lithium-ion batteries, they are unproblematic. If you are planning to install a photovoltaic system soon, check whether you really want to have lithium in your house or whether you prefer to rely on a safe and environmentally friendly battery technology.

The Author

Martin Mohr experienced the complete development of modern computer technology live. After his studies, he mainly developed Java applications. The Raspberry Pi rekindled his old love of electronics.

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