The Elusive Dream: Room-Temperature Superconductors and the Quest for Energy Efficiency

In the spring of 1911, in a laboratory at Leiden in the Netherlands, Heike Kamerlingh Onnes cooled a thread of mercury to about 4.2 kelvin, a fraction above absolute zero, and watched its electrical resistance vanish entirely. He had recently become the first person to liquefy helium, which gave him access to temperatures no one else could reach, and what he found in that frozen mercury was a phenomenon classical physics said should not exist: a current that, once started, would flow forever without loss. He called it superconductivity, and more than a century later the dream of achieving it at everyday temperatures remains one of the great unsolved problems in physics.

What superconductivity actually is

In an ordinary wire, electrons carrying a current constantly collide with the vibrating atoms of the metal and with impurities in its structure. Each collision sheds a little energy as heat, and that lost heat is electrical resistance. It is why a laptop charger grows warm and why long-distance power lines waste a meaningful slice of everything they carry. In a superconductor cooled below its critical temperature, resistance does not merely fall; it drops abruptly and exactly to zero. A ring of superconducting wire will sustain a circulating current for years without any power source to maintain it.

The explanation took nearly half a century to arrive. In 1957, the American physicists John Bardeen, Leon Cooper and John Robert Schrieffer proposed what became known as BCS theory, for which they shared the Nobel Prize in Physics in 1972. Their insight was that at very low temperatures, electrons stop behaving as lone particles that repel one another and instead bind into weakly linked “Cooper pairs.” These pairs move through the crystal lattice in a coordinated quantum state that glides past the obstacles that would normally scatter individual electrons. The same strangeness that lets particles behave collectively rather than individually runs through much of modern physics, and it is close kin to the effects harnessed in the emerging field of quantum computing.

The long climb up the thermometer

For decades, superconductivity was a curiosity confined to within a few degrees of absolute zero, reachable only with expensive liquid helium. Then, in 1986, two IBM researchers in Zurich, Georg Bednorz and Alex Müller, discovered that a brittle ceramic compound of copper oxide superconducted at 35 kelvin, far higher than BCS theory suggested was possible. The result was so unexpected, and so consequential, that they received the Nobel Prize the very next year, in 1987. Their breakthrough set off a frantic search that soon turned up related copper-oxide ceramics, the cuprates, superconducting above 90 kelvin.

That 90-kelvin mark mattered enormously, because it lies above the boiling point of liquid nitrogen, a coolant that is cheap, abundant and easy to handle. Suddenly superconductors could be kept in their working state without the costly apparatus that liquid helium demands. These “high-temperature” superconductors are already at work in MRI scanners, powerful research magnets, and experimental power cables. But “high” here is relative: 90 kelvin is still around minus 183 degrees Celsius. The genuine prize, a material that superconducts at the temperature of a warm room, has stayed maddeningly out of reach.

Why room temperature is so hard

Two obstacles stand in the way. The first is that the mechanism behind the cuprates and other exotic superconductors is still not fully understood. BCS theory neatly explains the low-temperature classics, but it does not adequately account for why the copper-oxide ceramics superconduct at the temperatures they do. Physicists have proposed competing theories involving strong electron correlations and intricate quantum interactions, yet no single explanation commands universal agreement. Without a solid theory, researchers cannot reliably predict which new materials will superconduct, and so the search proceeds partly by intuition and trial.

The second obstacle is the materials themselves. The most promising recent candidates are hydrogen-rich compounds, and the theory suggests hydrogen is a natural ingredient for high-temperature superconductivity. But squeezing hydrogen into the right configuration requires staggering pressures. In 2015, a sulfur-hydride compound was shown to superconduct at around 203 kelvin, but only when compressed to roughly 150 gigapascals, more than a million times atmospheric pressure, in a diamond anvil cell. A material that only works when crushed between two diamonds is a scientific triumph and a practical dead end.

Where superconductors already earn their keep

It is easy to talk about superconductivity as a distant prize and forget that a version of it is quietly at work all around us. The most familiar example sits in hospitals: the magnetic resonance imaging scanner relies on a powerful, exquisitely stable magnetic field, and that field is generated by superconducting coils cooled with liquid helium. Without zero resistance, the coils would overheat and the magnet could not hold its field steady enough to image soft tissue. Every MRI scan is, in effect, a piece of low-temperature physics doing routine clinical work.

The same principle powers the giant electromagnets that steer particle beams around accelerators such as the Large Hadron Collider, and the enormous magnets being built for experimental fusion reactors, where the goal is to confine a plasma hotter than the Sun’s core inside a magnetic bottle. Grid operators have trialled superconducting cables to carry dense currents through congested cities without the bulk of conventional copper, and superconducting fault-current limiters can shrug off electrical surges in milliseconds. All of this works today, using existing high-temperature materials cooled with liquid nitrogen. The catch is always the cooling: it is manageable in a hospital or a laboratory, but it rules the technology out of a phone, a car or an ordinary home. That is precisely the barrier a room-temperature material would demolish.

A cautionary tale of false dawns

The pressure to be first has produced some spectacular embarrassments. In October 2020, a team led by Ranga Dias at the University of Rochester announced in the journal Nature that a compound of carbon, sulfur and hydrogen superconducted at about 15 degrees Celsius, genuine room temperature, though again only at extreme pressure near 267 gigapascals. It was hailed as a landmark. But other physicists could not reconcile the reported data, particularly the way the raw measurements had been processed, and in September 2022 Nature retracted the paper. Further papers from the same group were subsequently retracted as well, amid allegations of data problems.

The field has learned to greet dramatic claims with caution for good reason. In the summer of 2023, a Korean group’s announcement of a room-temperature, ambient-pressure superconductor they called LK-99 set the internet alight, only for laboratories from Beijing to Berlin to fail to reproduce the effect within weeks; the apparent signal was traced to impurities rather than superconductivity. Each of these episodes is a reminder that extraordinary claims in this field require reproducible evidence, and that peer review and independent replication are not bureaucratic hurdles but the immune system of science.

What the prize would be worth

The stakes explain the fervour. A practical room-temperature superconductor operating at ordinary pressure would transform how electricity is generated, moved and stored. Roughly a tenth of all electricity generated is lost as heat before it reaches the socket; lossless transmission lines would recover much of that. It would make ultra-efficient motors, compact and powerful magnets for fusion reactors and maglev trains, and faster, cooler electronics. The same relentless drive to squeeze inefficiency out of everyday technology has quietly reshaped ordinary objects already, as the evolution from sundials to smartwatches shows in miniature. A superconductor at room temperature would be that kind of shift applied to the entire electrical grid.

Fun facts

• Heike Kamerlingh Onnes discovered superconductivity in 1911 only because he had, three years earlier, become the first person ever to liquefy helium.
• BCS theory is named for its authors Bardeen, Cooper and Schrieffer; John Bardeen is the only person to have won the Nobel Prize in Physics twice, the other being for the transistor.
• The 1986 cuprate discovery earned Bednorz and Müller a Nobel Prize in 1987, one of the fastest turnarounds from result to award in the prize’s history.
• A superconducting ring can carry a persistent current for years with no power source, and such currents have been measured drifting less than one part in billions.
• The much-hyped LK-99 claim of 2023 collapsed within weeks when its apparent superconductivity was traced to a copper-sulfide impurity.

A closing reflection

There is something clarifying about a problem that has resisted more than a century of the world’s cleverest people. Superconductivity is not science fiction; it is real, reproducible and already useful, provided you are willing to pay in cold or in pressure. The elusive part is the last mile, the material that asks for neither. Perhaps it will arrive from a theory not yet written, or perhaps from a stubborn experimentalist testing the thousandth combination of elements. What the false dawns of recent years really teach is not that the goal is impossible, but that the moment it is finally reached, we will know, because it will be reproduced everywhere, by everyone, and it will stay true.