Since the mid-eighties we've been promised so called "room temperature" superconductors were going to change everything.  So, whats up?

Superconductors are materials that exhibit superconductivity. 

Superconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect).

The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, impurities and other defects impose a lower limit...The resistance of a superconductor, despite these imperfections, drops abruptly to zero when the material is cooled below its "critical temperature". An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source.

So what?  Big fracking deal!  Right?  Well, it is a big deal.

Superconducting magnets are some of the most powerful electromagnets known. They are used in MRI and NMR machines, mass spectrometers, and the beam-steering magnets used in particle accelerators.

Promising future applications include high-performance transformers, power storage devices, electric power transmission, electric motors (e.g. for vehicle propulsion, as in vactrains or maglev trains), magnetic levitation devices, and Fault Current Limiters.

Maglev trains alone would be a good realization of this technology.

Magnetic-levitation is an application where superconductors perform extremely well. Transport vehicles such as trains can be made to "float" on strong superconducting magnets, virtually eliminating friction between the train and its tracks. Not only would conventional electromagnets waste much of the electrical energy as heat, they would have to be physically much larger than superconducting magnets. A landmark for the commercial use of MAGLEV technology occurred in 1990 when it gained the status of a nationally-funded project in Japan. The Minister of Transport authorized construction of the Yamanashi Maglev Test Linewhich opened on April 3, 1997. In December 2003, the MLX01 test vehicle (shown above) attained an incredible speed of 361 mph (581 kph).

The problem used to be that materials superconducted only at extremely low temperatures, but in 1986 so called high temperature superconductors were discovered.  These new materials needed to be chilled to "only" 92K (-293.8F).  This was significant because liquid nitrogen is colder at 77K (-320.8F) and cheap enough and easy enough to work with commercially.  If you lived through the mid-eighties maybe you remember as I do the frenzy over the levitating magnets (pictured above.)

But the ultimate goal is a room temperature superconductor.

A room-temperature superconductor is a material yet to be discovered which would be capable of exhibiting superconducting properties at temperatures above 0° C (273.15 K). This is of course not strictly speaking "room temperature" (20-25°C); however, it can be reached very cheaply.

If superconductors could be made to work at temperatures as high as room temperature, they could have potentially limitless applications.

Such as? 

One exciting applications is using superconducting wire to provide lossless power transmission from power stations to cities. Superconducting wire can hold a much higher current density than existing copper wire and is lossless and therefore energy saving.

So, how is the search going?  Pretty good, in fact.  In the last few years there have been a slew of new materials and new theories.  The highest temperature yet achieved your humble bloggist could find was 242K or -24F.  

At any rate, if we keep the pace up, we may just yet acheive room temperature superconductors within the near-term future.

Stay Tuned.