There are superconducting magnets. They are able to support a high current density with a small resistance. They generate intense magnetic fields with little or no electrical power input.
Maybe reading about the Meissner Effect will give you a better understanding. This is copied and pasted from who knows where. It was a long time ago.
Why are some materials capable of magnetization, like iron, while others seem unaffected by an external magnetic field? The answer is in the magnetic susceptibility or permeability. It is much easier to discuss magnetic properties in terms of relative permeability of materials. Materials with high permeability exhibit high magnetization when placed in an external magnetic field, while those with low permeability do not.
There are three defining terms for permeability, diamagnetic, paramagnetic, and ferromagnetic. All materials fall into one of these categories. Diamagnetic materials have a relative permeability of less than 1. Examples are mercury, gold, silver, water, silicon, etc. The temperature plays a large role in permeability. It is easier for the magnetic dipoles to align at lower temperatures. Higher temperatures create more agitation and movement so it becomes more difficult to align dipoles.
The permeability of most diamagnetic material range from 0.9999 to 0.99999, so for the most part they can be considered non-magnetic. One notable exception to the negative susceptibility is superconductors. These materials are pure diamagnetic, like diamagnetism on steroids. Their permeability is always zero. The defining characteristic of a superconductor is known as the Meissner Effect . Inside the material, the magnetic flux is always zero. An interesting aspect is that the inside of the magnetic flux is lower than the outside-applied magnetic field, so a magnet will float and be repelled by the diamagnetic material. The magnetization of the internal dipoles will always oppose an externally applied field. This force is extremely small, and all other forces, even gravity usually dominates. The exception is in superconducting material, in which this force is very large. This repulsion is why a magnet will float above a superconductor.
One atomic model of this has orbiting electrons and electron spins that cancel each other out under normal conditions, but under the influence of an external field, the field of the orbiting electrons is slightly smaller than the spinning of the electrons. This in turns causes an opposing force. In paramagnetic material, the orbit is in the direction that contributes to it being attractive and in the diamagnetic material the electron orbit in the opposite direction contributing to its repulsion.
Another notable observation is that the magnet above the superconductor does not slide off. This is caused from flux pinning, which only occurs in Type II superconductors. The flux lines do not move in spite of the Lorentz force acting on them. They become trapped or pinned. Flux pinning is only possible when there are defects in the crystalline structure of the superconductor, usually from impurities or grain boundaries. The magnetic field is able to penetrate through these defects. You can picture flux pinning like lines of the magnetic field or strings that are stuck within the material. When the magnet is lifted, this enables the superconductor to be lifted with it, but at the same time keeping its distance. http://en.wikipedia.org/wiki/Superconducting_magnethttp://hyperphysics.phy-astr.gsu.edu/hbase/solids/scmag.html