Superconductivity allows for 100% efficient electric transmission, meaning no heat loss. Modern CMOS circuits dissipate around 1 pJ (10^-12) per bit. Thermodynamics requires that when you destroy a bit of information you generate at least 2.9×10^-21 J (the Landauer's principle). So, even if we are limited by the Landauer's principle, microelectronics using superconductors would still be a 9 orders of magnitude improvement. It would be feasible to have a CPU that uses microwatts instead of hundreds of watts.

We will be able to move electricity across borders and regions cheaply to reduce the cost of electricity.

Essentially unlimited desalination in places with water issues plus the cost to transport it just went way down.

Magnetohydrodynamic (MHD) propulsion uses magnets to accelerate a conductive fluid (like ionized gas). It is a thruster with no mechanical moving parts, and can theoretically be much more efficient due to less friction. Currently MHDs are just experimental, and are not commercially viable due to the energy required to power the magnets and the logistical challenges of dissipating heat - both of which may be easier with high temp superconductors.

Superconductors are essential for maintaining the quantum state of qubits, the building blocks of quantum computers. Currently, superconducting qubits need to be cooled down to extremely low temperatures to minimize thermal noise and to maintain the delicate quantum state. This requires complex and expensive cooling infrastructure. If room-temperature superconductors were to become a reality, the need for such cooling would be greatly reduced, potentially lowering the cost and complexity of building and maintaining quantum computers.

Fusion reactors.

Obviously they have several more challenges, but having a slimmer cooling system would make the overall design much leaner.

Alongside @whalelang's comment on CMOS circuits, and on the opposite end of sexiness, we have the possibility for much higher efficiency transformers in power electronics. Modern pre-LK designs are already able to achieve roughly 50% savings in both waste electricity and size, but the low temperatures we currently have to maintain to keep them operating have proven a bottleneck to widespread adoption. As for why this is a great idea, really dense transformer technology = cheaper electricity prices = cheaper everything.

MRIs heavily relly on mormal expensive super conductors. Room temperature ones could make them way smaller due to not needing cooling and a lot more accurate to. Image mobile MRI scanners at every medical checkup or even as a home appliance. Like a incredibly powerful X-ray, just in more detail with no downsides. It would make detecting health problems a lot easier.

1. Maglev Transportation: Enhanced magnetic levitation trains will revolutionize the transportation industry, enabling faster, more energy-efficient travel.

2. Grid Energy Storage: Large-scale, efficient energy storage and transmission on the power grid.

3. MRI Advancements: Improved Magnetic Resonance Imaging (MRI) machines that are cheaper and more accessible.

4. Efficient Quantum Computing: Leap in quantum computing technology due to efficient qubit management.

5. Space Exploration: Superconductors could facilitate the development of advanced propulsion systems for space travel.

6. Highly-Efficient AI Systems: Enabling the use of more complex AI models like GPT-4 in consumer-grade equipment, significantly expanding AI's accessibility and application range.

7. Affordable Cloud Storage & Servers: With superconductors, server farms could operate more efficiently, reducing their energy costs, which could translate into cheaper cloud storage and services.

Practical, man portable, high velocity/foot pounds of energy coil guns.

While the below applications are certainly more useful, RTSC's actually give us the option of sci-fi guns. Which is so cool!

(For current work, look at Arcflash labs. Look at how much of the overall mass/volume goes into heat dissipation)

SMES (superconducting magnetic energy storage) is used now to stabilize load on power grids, but impractical much of the time because of cooling requirements. I think SMES units are less dense than chemical batteries but charge and discharge extremely fast. The new alleged superconductor apparently has a really low critical field strength, though, limiting how effective it is for this.

Cheap usable maglev trains!

Also, cheap MRI machines!

By definition, the coolest application will be room temperature.

levitating art

Mach-35 railguns (12km/s) to shoot down ICBMs and satellites and moon bases. I pessimistically estimate 4500 newton-seconds of drag per cm^2 of cross sectional area to get out of the atmosphere at that initial speed so if the projectile is a 50cm long and made of DU it would only lose about 500m/s on the way out due to drag.

An iPhone that doesn’t get hot when you watch a movie on it