Hitachi Maxell came out with a LED lantern called MIZUSION a while ago that’s powered by water and salt. My first thoughts would be that this would be good for those who live along the coast since they can easily get salt water from the ocean during emergencies.
The way this works is you pour in water and salt and it creates power. But salt water isn’t the only part of it though. The other part of the equation is that there is a magnesium bar in the unit that serves as the cathode and oxygen that serves as the anode. The salt water is the electrolyte. Basically, all you did by adding the salt water is to finish building the battery to power the lamp.
Part of the marketing campaign is that you may have easy access to water and salt in your house but you may not have access to extra batteries. In most cases, I would say this to be true. Not many households have extra batteries laying around. They usually buy the batteries from the market only when you need them. But in an emergency, the markets may be closed and so forth so you have to use what you have at home.
With a brand new magnesium bar, it can power the lantern for up to 80 hours. After that, you can replace it with a new magnesium bar. My issue with this is that if you don’t have access to new batteries, you can wait until the markets open. But, if you run out of the magnesium bar, no local store will carry this. You’ll have to order it and wait for delivery.
It’s definitely a novel idea and one of those gadgets that you would show off to others. But in a real emergency, I think one of the tried and true lanterns would be a hand crank one. You’ll never run out of power since you’re the one powering it. The other option would be a solar lantern that you can recharge during the day and use at night. With a hand crank or solar lantern, you never need to purchase anything to power it.
I’m the type of person who likes to be self-reliant. If I purchase a product that requires items that need occasional refill, I’m at the mercy of that company to continue manufacturing those parts and I don’t like that feeling. If I can go down to the nearest market or other retail store to get those refills whenever I need them, I’m ok. If I have to order them, I don’t think I would consider getting the product.
Again, it’s a novel idea, but in my mind, not a practical one for emergencies.