Can Electricity Go Completely Wireless?

How much electricity does a person consume? Could we do without wires? Let’s explore the latest discoveries and promising achievements in materials science.

Wires are everywhere, carrying both information and energy. While wireless technologies for information transfer have advanced rapidly, energy transmission is a different story. Various methods exist for transporting energy over distances. For instance, gasoline transport by tanker truck or even launching a nuclear missile can technically be considered a form of energy transmission—wireless. However, these methods are far from matching electricity in terms of convenience and versatility.

Electricity is generated at power plants—thermal, nuclear, hydro, etc. The energy produced is transmitted through wires to consumers (households and industries), where it is used for productive work, heat, and emissions. Valuable work includes, for example, the operation of electric motors in a refrigerator’s compressor or the movement of a trolleybus. Heating water in a kettle counts as heat production. The energy consumed per unit of time is called power consumption and is measured in watts. For example, an electric kettle consumes around 2000 watts (or 2 kW), while a mobile phone, when charging, uses less than 10 watts.

Transmitting information also requires energy. For example, a cell tower transmitter uses about 1 kW, which is still far less than what industry and households consume.

A basic formula, Ohm’s Law (P = U⋅I), is taught in schools: P is power consumption, U is the voltage (in volts), and I is the current (amount of charge passing through the wire per unit time, measured in amperes).

Household outlets have a voltage of 220 volts. When a 2 kW kettle is plugged in, the current drawn is around 10 A. Imagine a large city like St. Petersburg, with a million households consuming roughly the same 10 A. It’s not because everyone is boiling kettles all day but because appliances like refrigerators, lighting, computers, air conditioners, and washing machines continuously cycle intermittently throughout the day. Approximately 2 GW would be needed to power a million-person city—about the output of two nuclear reactors. Industrial use and electric transportation would add to this number.

This raises the question: How do we provide the necessary power to consumers? With wires, this becomes possible. Wireless energy transmission would require electromagnetic radiation, meaning an antenna (or laser for optical or infrared ranges) would emit the energy, and a receiver would capture it. The problem is that any radiation source cannot perfectly direct the wave to the receiver due to diffraction, which causes waves to spread.

The wave will always disperse. If the receiver is hundreds of kilometers away, it will capture only a small fraction of the energy while the rest is lost. Thus, effective wireless power transmission over long distances isn’t feasible at any reasonable frequency. Another issue is the interaction of the energy beam with air, dust, and living organisms. Anything alive caught in a 1 GW beam would instantly burn or vaporize.

So, to provide 2 GW of electricity to our hypothetical city, wires are essential. What limits the current that can flow through a wire? It’s the wire’s heating: thin wires heat up more than thick ones when carrying the same current. A thin copper wire is fine for a small lightbulb, but a thicker wire is needed for a kettle, which draws more current. Ultimately, the wire thickness is determined by electrical resistance. If a large current passes through a thin wire, it can overheat or even burn.

A kettle’s power cord typically has a cross-section of 1.5–2.5 square millimeters (1 square millimeter of copper can carry about 10 A). Of course, for a city with a million kettles, no one would build a wire with a million-square-millimeter diameter; global metal resources would be exhausted. Instead, we increase the voltage to reduce the need for thick wires. Power transmission lines from power plants operate at voltages far higher than 220 V, reaching up to 220 kV or 1 MV. Here, wire thicknesses reach 300 square millimeters, capable of carrying around 500 A. Multiplying 500 A by 220 kV gives roughly one-twentieth of the city’s needs. The result is that a large city would require about ten medium-sized high-voltage power lines.

However, these lines, made from copper or aluminium with steel, still heat up, leading to energy losses. The longer the line, the greater the losses due to resistance, with potential losses reaching 10–30%. This lost energy heats the surrounding environment. One possible solution to eliminate these losses is to use superconducting cables.

Superconductors

Superconductivity was discovered over a century ago, revealing that certain materials lose electrical resistance and can carry current without energy loss. Most known superconductors only exhibit this property near liquid helium temperatures (-269 °C, or about 4 K). However, high-temperature superconductors (HTS), which work at the more manageable temperature of liquid nitrogen (-196 °C, or 77 K), also exist.

Room-temperature superconductors haven’t yet been realized. If they were, lossless power transmission would become possible, representing a major energy-saving breakthrough.

From the late 1990s to the early 2000s, scientists learned to create HTS wires that operate at liquid nitrogen temperatures and, despite their small size, can carry large currents—hundreds to thousands of amperes.

What challenges remain? First, as mentioned, HTS wires require liquid nitrogen, and second, they’re far more expensive than copper. Nonetheless, pilot lines with these superconductors exist in New York and Germany. Superconducting lines must be enclosed in double-walled pipes (thermos pipes) filled with liquid nitrogen, which must be topped up as it evaporates. Operating such lines is costly, often requiring a small liquid nitrogen plant nearby. However, superconducting lines avoid voltage losses and can carry tens of thousands of amps, meaning lower voltages can be used. Unlike traditional high-voltage lines, which require clear zones where building or farming is prohibited, superconducting lines don’t need this, freeing up land for other uses.

Achieving room-temperature superconductors is challenging because these materials are complex, often containing 4–5 elements in a highly ordered crystal lattice, such as yttrium-barium-copper oxide (YBa2Cu3O7−x) or bismuth-strontium-calcium-copper oxide (Bi2Sr2Can−1CunO2n+4+x). Maintaining this crystal orientation along the entire length of a multi-kilometer HTS wire is difficult, as the wire’s crystal structure must align perfectly over its entire length. The manufacturing process is complex, involving multiple layers, where the HTS layer is a tiny fraction.

Wireless Power Transmission

Wireless power transmission exists today, as seen in wireless phone charging. However, this isn’t entirely wireless; it functions as a transformer, transferring energy through a magnetic core. Wireless charging only works when the surfaces (with ferrite elements inside) are nearly touching. Moving the device away stops charging, as magnetic fields quickly weaken with distance. Charging over short distances could theoretically be done via antenna or laser, but current receivers like solar cells have low efficiency, which limits the possibilities of wireless energy transmission. 

References

1. Kamerlingh Onnes, Heike Further experiments with liquid helium. C. On the change of electric resistance of pure metals at very low temperatures etc. IV. The resistance of pure mercury at helium temperatures / Proceedings of the Section of Sciences. 1911
2. World’s First HTS Power Transmission Cable System is Underway / Electrical Products
3. World’s longest superconductor cable proves successful / Institution of Mechanical Engineers. 2014