A device can supposedly create a tiny current by manipulating Earth’s magnetic field as the planet rotates.Credit: Getty
Electricity can be generated from the energy of Earth rotating through its own magnetic field — according to a provocative claim put forward by physicists today.
The findings are controversial but intriguing, researchers told Nature. The effect was reported only in a carefully crafted device and generates just 17 microvolts — a fraction of the voltage released by a single firing neuron — making it hard to verify that some other effect isn’t causing the observations.
If the phenomenon is real and the device could be scaled up, it could generate emission-free power while remaining static, which could potentially be useful in remote locations or within the body. The authors published their findings in Physical Review Research1 and presented them at a meeting of the American Physical Society in Anaheim, California.
“The idea is somewhat counterintuitive and has been argued since Faraday,” says Paul Thomas, an emeritus physicist at the University of Wisconsin, Eau Claire. But the experiments, led by Christopher Chyba, a physicist at Princeton University in New Jersey, are very carefully done, he adds. “I find it very convincing and remarkable.”
Others agree that the results are striking but remain sceptical. Rinke Wijngaarden, a retired physicist most recently at the Free University of Amsterdam, has followed the authors’ claims since 2016 and failed to find the effect in his own experiments in 2018. He finds the work very interesting, but is “still convinced that the theory of Chyba et al cannot be correct”.
Planet power
In theory, the device would work in a similar fashion to an electrical power station, in which passing a conductor through a magnetic field causes electrons to move, creating a current. As Earth rotates and part of its magnetic field remains static (at least according to a 1912 proof) a conductor on its surface would move through some components of the field.
Normally this would not create a current, because in a uniform field like Earth’s, electrons feeling this push would rearrange themselves to create an opposing electric force, ultimately leaving charges static (this does not apply where the force a conductor feels is constantly changing, as in a generator).
But Chyba and his colleagues say they have found a loophole. Using a complex calculation, they showed that certain materials — with unusual properties and when shaped into cylindrical tube — could channel Earth’s magnetic field into a strange configuration. This, they argue, would create a magnetic push that the electrostatic force within the device could not cancel, generating a current.
To demonstrate their theory, the researchers crafted a device that fulfilled their requirements: a hollow cylinder made from a soft magnetic material containing manganese, zinc and iron. While controlling for other effects, they looked for any voltage and current running through the device. The result verified their predictions: they observed a tiny 17-microvolt voltage that depended on the set-up’s orientation with respect to Earth’s magnetic field. The voltage was zero when they used a solid chunk of the conductor, rather than a hollow tube.
“The observed voltages are so small that there are many potential spurious causes available,” says Wijngaarden, but he points out that Chyba’s team has “gone to great lengths to try and avoid” other effects that could mimic their predicted phenomenon, such as temperature variations.
