US military wirelessly transmits electricity over a kilometer

In principle, electricity can also be transported without a cable. This is reflected, for example, in inductive chargers for smartphones. Some developers are also working on systems that will transfer the principle to electric cars. The US military is pursuing even more ambitious plans. They want to drive troops into distant lands from space. Background: Until now, the troops had to be regularly refueled during their missions. This poses significant logistical problems. This problem is to be solved by so-called power beaming, ie wireless power transmission over long distances. After years of research, military researchers have now successfully completed an important test. They sent an electrical power of 1.6 kilowatts over a distance of one kilometer. This showed that the approach works in principle. In theory, there is nothing to prevent transmission over considerably longer distances.

Image: Gayle Fullerton / NRL

Even when it rained, the power transmission worked

In order to be able to transfer the electricity, it is first converted into microwaves. A scale is then used, which generates a concentrated beam and directs it towards the receiver. At the destination, in turn, is a collection of small microwave antennas. This so-called rectenna serves to receive the beam. A diode then ensures that the electromagnetic waves become direct current again. The tests now performed took place at two different locations. The peak power of 1.6 kilowatts was achieved at an army compound in Maryland. In contrast, the MIT campus in Massachusetts had a significantly higher average output. It was also possible to test the technology under sub-optimal weather conditions. But even in heavy rain, the power loss was only five percent. This is not entirely unimportant for use in practice. Because army units logically do not only operate when the sun is shining.

Theoretically, green electricity could be produced in space in the future

In the past, there have also been experiments with wireless energy transfer with lasers. Here, however, the beam always had to be turned off if a living creature approached. However, this is no longer necessary with the current microwave transmission that has now been tested. On the contrary, the researchers involved ensure that its use does not endanger humans or animals. This also increases the usability of the approach. Theoretically, the possible applications of the technology also extend far beyond the military sector. It is conceivable, for example, to place enormous solar panels directly in space and to wirelessly transport the green energy generated in this way to the earth. This would have the advantage that solar energy would be available in large quantities around the clock. Such mind games, however, belong to the future. At the very least, the US military’s Naval Research Laboratory seems determined to push the approach further.

Via: Naval Research Laboratory