I keep seeing stories about a new lamp that is “powered” by salt water. The claim is that you’ll get 45 days of lighting using nothing more than half a liter of salt water…
What I want to know is why none of these journalists ever check with an engineer or physicist or high school science teacher on whether such a claim is possible. If it’s not obvious to you, the answer is no, salt water alone doesn’t produce electricity. If it did, every coastal city would just pull power from the ocean instead of burning coal and gas or bothering with wind and solar.
So is this bad journalism or outright fraud?
Dig into the details and it seems this device is powered by a non-obvious battery. Not your typical off-the-shelf battery, which would undoubtedly be less expensive than what powers this lamp. Nor a rechargeable battery and solar panel, which is what is now ubiquitous across the emerging markets. No, this device contains solid or powered magnesium and the salt water is the electrolyte conducting an electric current, just like a battery as that magnesium oxidizes.
What the journalists and company are ignoring is the fact that when the 45 days is over, no amount of fresh salt water is going to power the lamp again. To do that you need a new chunk of magnesium metal. What is the cost of that, and the environmental footprint of that? None of the articles bother to say.
What might that cost? You can order magnesium powder for $162 per kilogram on Alibaba today.
I like to think frauds like this don’t mean to be frauds, that the inventor instead had the idea of mixing water and magnesium to make power, made it work, got excited, and then didn’t care that the solution was 10x or 20x or 100x more expensive than the existing solutions, skipped over that flaw, and focused on the salt water instead.
But meanwhile, stories like this don’t get lights into homes that don’t have them, nor help fund real solutions to make that happen. So journalists, next time please take a few minutes to do your homework. Next time write the clickbait title of “45 day salt water lantern is a physics bending fraud” instead of making it sound real.
