larry fisher, a former New York Times reporter, writes about business, technology and design.
Published March 22, 2023
Some technologies take so long to deliver on their potential that they turn into punchlines, with every nanometer of alleged progress greeted with suspicion if not derision. So it has been with superconductors, materials that allow electricity to flow without resistance. Maybe it’s time to get ready, though, for a serendipity: Research just published in the prestigious scientific journal, Nature, by Ranga P. Dias and colleagues at the University of Rochester, reports on a new metal that is superconductive at near-ambient temperature.
Conductors, Semiconductors and Superconductors without Tears
First, a soupçon of science for the humanists in the audience. In physics, a conductor is a material (most commonly a metal such as copper, silver or gold) that allows the flow of electrical current. In contrast, an insulator is a material that restricts the flow — think glass and numerous sorts of plastics. Semiconductors combine the characteristics of both conductors and insulators: their resistance can be varied, allowing them to function as electrical valves. Silicon compounds (as in the eponymous Valley) are the most common semiconductors, followed by gallium arsenide.
As electrons move through a conductor, some collide with atoms, other electrons and impurities in the medium, and these collisions create heat, draining away the amount of electrical energy that emerges. Even the best conductors were long thought to have some resistance — which is why circuit breakers are needed to prevent your house wiring from starting fires when you turn on umpteen appliances. But in 1911 the Dutch physicist Heike Kamerlingh Onnes found that the resistance in mercury completely vanished when it was cooled to the temperature of liquid helium (-452° Fahrenheit, only a few degrees above absolute zero).
Early on, scientists could explain what occurred in superconductivity, but the why and how remained a mystery for nearly a half century. It was only in 1957 that three American researchers — John Bardeen, Leon Cooper and John Schrieffer — established the microscopic theory of superconductivity, for which they shared the Nobel Prize in Physics in 1972. Then, in 1986, scientists discovered a new class of copper-oxide materials that exhibited superconductivity, some of them at above the temperature at which nitrogen becomes a liquid (-321° Fahrenheit).
Needless to say, that is still extremely cold. But super-conduction is such a valuable property that despite the energy requirements of reaching and sustaining the necessary conditions, “high-temperature” superconductors had global sales of $6.5 billion in 2022. You are most likely to have encountered them up close and personal in MRI scanners, where they facilitate the powerful sustained electromagnetic fields needed by these machines. Maglev trains like the Shanghai Transrapid, which has a top speed of 270 miles per hour, use superconductor electromagnets to float just above the track, reducing friction to nearly nothing
But along with deep freezing temperatures, currently used materials only achieve superconductivity at pressures over a million times atmospheric levels — and that takes energy, too. So for superconductors to achieve anything like their full potential, they would have to function at something closer to earthly parameters.
Enter Dr. Dias.
Room temperature superconductors still look like a long shot, but some previous long shots have paid off big time.
Breakthrough to Bust to Breakthrough
Little known outside physics circles, Dias labored in relative obscurity for years, searching for new materials that might be superconductive in more manageable conditions. He began his studies at the University of Colombo (Sri Lanka) before moving on to Washington State University, Harvard and Rochester. Along the way he made slow, incremental advances that are more typical of scientific research than the breakthroughs that generate splashy headlines.
But the headlines did arrive in October 2020 when Nature published a paper from Dias’s lab reporting on a blend of hydrogen, sulfur and carbon that became a superconductor at a balmy 59 degrees Fahrenheit — albeit only after it had been squeezed to enormous pressure. Time named Dias to its eponymous “100 Next” list of people shaping the future.
The slings and arrows arrived soon after the accolades. Jorge Hirsch, a physicist at the University of California (San Diego), attacked some of the paper’s findings, alleging fraud and fabrication of data. Nature withdrew the paper, with the provision that the Dias group could resubmit it — which they have done.
But the new paper is splashier still. In it, the researchers describe a new hydride material that exhibits superconductivity at 69 degrees Fahrenheit and 10 kilobars (145,000 pounds per square inch, or psi) of pressure. Now, 145,000 psi is not a casual achievement — air pressure at sea level is about 15 psi — but it’s a fraction of the pressure needed for currently available superconductors.
“The good news” Dias says, “is there are already industrial techniques to achieve that level of pressure. The pressure where we are right now is already in the commercially available range, using standard techniques.”
Of course, Dias’s results will have to be replicated to qualify him for the Nobel sweepstakes. “What happened with the previous work was really unfortunate,” he lamented. “We completely deny all these allegations of fraud, data fabrication. … When Nature retracted, we were very confused.”
Dias’s group redid its measurements and reconfirmed superconductor transmission at the Department of Energy’s Argonne National Lab in Illinois. “We gave them all the data, all the methods, everything we developed,” Dias adds. Now, “Nature is reviewing our 2020 work again. Even with all the pushback, we keep pushing forward.”
While working to reduce the ambient pressure needed, Dias will also focus on producing the new hydride in quantities greater than the tiny amounts used in experimentation. “We are figuring out how to grow this material, using standard methods,” he explains. “To talk about nuclear fusion, electrical airplanes, frictionless bearings, you’re talking about going from gram to kilogram quantities to thousands of tons.”
Dias expects the first applications will be in small electronic devices, rather like the way semiconductors first appeared in pocket transistor radios. Just when, “I really don’t know,” Dias acknowledges. But “we are really right on the edge.”
Better, Faster, Cheaper
How seriously should we take him? Room temperature superconductors still look like a long shot, but some previous long shots have paid off big time. For example, Steven Chu, President Obama’s first secretary of energy, said in 2003 that hydrogen fuel cells needed four miracles to become viable — an event he deemed unlikely in the next 20 years. Now you can jump on a city bus powered by hydrogen fuel cells, or buy fuel cell cars off the shelf from Toyota and Hyundai.
Jonathan Koomey, a former Stanford professor specializing in energy technology and the environment, speculates that the real uses for superconductors may not be apparent for some time. “The basic argument is that if you can achieve superconducting devices at room temperatures, you can vastly reduce energy losses,” Koomey explained. Hence their attraction for thousand-mile transmission lines and trains that float on electromagnetic fields. However, the immediate value may not be in eliminating energy losses “but in better service, faster computing. … I feel like we are just at the very beginning of people trying to design new gadgets using this technology.”