Battery sucks electricity OUT OF HUMID AIR

Scientists from Tel Aviv University have developed a battery that can self-charge using air with high humidity. It could become an important source of renewable energy particularly in tropical countries. Most of Australia’s coastal areas are humid enough to benefit.

Hydropower – the generation of energy from water – is not new; we have long harvested mechanical energy from dams, and hydrogen fuel from electrolysis of water. But now a team of scientists aims to take hydropower to a whole new level. The scientists have invented a battery that charges itself when exposed to air with a humidity higher than 60%.

The inspiration dates far back to 1843, when famous physician Michael Faraday looked into an incident in London where a worker died of an electric shock from a steam boiler. The boiler’s steam had somehow created an electric charge in the boiler, and after a series of experiments Faraday concluded that the electricity came from the friction between the water vapour and the boiler’s metal surface.

Intrigued by this story, scientists from Tel Aviv in Israel created an experiment to test whether they were able to generate electric charge in different types of metal via contact with water vapour. They built a device in which moist air passed into a sealed Faraday cage that would keep external electricity out of the experiment. In the cage there was a brass cylinder with a ground connection, and inside the cylinder, they placed the metal test material. By measuring the voltage difference between test material and brass cylinder, the scientists could determine whether the water vapour created a voltage in the test material. And it did. While some metals were unaffected, others became charged. The results were particularly good with zinc, for which an air humidity level of 60% could make the device – effectively now a battery – charge itself to a voltage of 1V. That’s close to the charge of an ordinary 1.5V AA battery as used in everything from remote controls to flashlights.

The scientists believe their invention offers huge potential, particularly in developing nations where many people still lack access to stable or cheap electricity, and especially for those in the tropics, where air humidity levels would charge the batteries at most times of the year. Australia’s coastal regions could benefit, as the annual humidity averages above 70%, and higher in the mornings. Inland, however, humidity levels are lower, and the batteries would fail to charge more often than not.