The SALt Lamp Explained

You might have seen this in the New York Times today:

The president hosted a discussion of climate change at the chief executives’ forum along with Jack Ma, founder of the e-commerce giant Alibaba, and Aisa Mijeno, a Filipino entrepreneur who invented a lamp that runs on saltwater.

In response to a question about her lamp from Mr. Obama, Ms. Mijeno said that it provided about eight hours of light, as well as power to a USB port for charging a phone. “And all you need to do is you just have to replenish the saltwater solution,” she said, “and then you have another eight hours of lighting.”

Just saltwater? Doesn’t that seem like it violates some kind of energy conservation law?

Yes and no. The SALt lamp uses a fairly ordinary galvanic battery that consists of two electrodes and an electrolyte solution of salty water. Replenishing the saltwater will indeed get the lamp going again, but you also need to replace the anode every six months or so. There’s no magic here, but there is a substantial engineering challenge. “It is made of tediously experimented and improved chemical compounds, catalysts, and metal alloys that when submerged in electrolytes will generate electricity,” Mijeno explained earlier this year.

The other challenge is being able to manufacture the lamp so that it’s reliable, cheap, and easy to maintain. If Mijeno’s lamp works as advertised, it will produce about 90 lumens of light at a cost of $20, plus $3 every six months for a replacement anode. It’s designed for areas with no electricity grid, and should be safer than kerosene lamps. She hopes to have it on the market in 2016.