Those living off grid can probably tell you how important good, reliable, and affordable batteries are. Whether generating your power through solar, wind, hydro, or other means, having a way to store that power can be vital. For now the most advanced systems are using Lithium Ion based batteries, but a South Korean University may be on the verge of a transition that would replace the more expensive and often difficult to mine, lithium, with very common and easily accessible seawater. The seawater based battery is technically a sodium-air battery, but the seawater is very promising catholyte. So far the prototypes are still lagging behind similar size lithium ion systems when it comes to energy discharge, putting out around 2.7 Volts compared to 3.6 to 4.0 for lithium ion, but these are still early trials and scientists are hoping to match or even surpass the current technology. Such a transition would severely reduce the environmental impact of mining rare materials and finding ways to dispose of the hazardous byproducts. A Tesla Powerwall system that uses a seawater based battery is still a long way off, but it could be a big step up in off grid power systems when we get there.