Superconducting Power Grid Launches In New York

EmagGeek writes "IEEE is running a story about a new superconducting power grid that was energized in April in New York State. The lines operate at 138kV and are cooled to 65-75K to maintain superconductivity. These lines are run underground and can carry 150 times more electricity than copper lines of the same cross section. The project is funded with taxpayer dollars through the Department of Energy." A related story at MarketWatch indicates that this is part of a large-scale effort to upgrade aging infrastructure.

Comments

Superconductors = almost no heat

[DrYak]

how much energy does it cost to keep them so cool?

Not as much as you may think.

The whole point of using super conductors is that their resistance is incredibly low, almost 0 ohm. They are thus highly efficient and don't lose much energy into heat through Joule effect, compared to classical conductors used in regular power lines. They will naturally stay cool.

So it costs some significant amount of power to cool them down to their working temperature, but once there, the super conductors keep their temperature almost for free, you only have to make up for what is lost because of the insulation.

Similar superconductors are used in the high-field super-magnet inside medial MRI machines. And those machine doesn't need a whole nuclear plant's worth of energy to keep them cool.

Re:Superconductors = almost no heat

[Antique Geekmeister]

But they do have impedance (which often confuses people). They also have radiative losses: some electro-magnetic enegy can, and will, couple into nearby objects and be dissipated there.

Re:Superconductors = almost no heat

[OldMiner]

You use the right words for an electircal engineer, but your conclusions are inaccurate.

Skin effect doesn't reduce inductive losses. It just means you generally increase resistive losses bceause your effective cross section is reduced. High voltage AC transmission lines are famously inductive, such that transmission line workers where metal mesh in their suits so they don't get the weird feeling of the oscilating magnetic field through their bodies.

And, no, long distance transmission lines are most decidedly NOT DC in the U.S. Now, in Brasil and China, yes, long haul DC transmission lines exist. But they have to pay a huge cost in terms of equipment for this. It's balanced out due to the decreased construction cost and resistive losses. Long haul DC lines are only economical when you have a massive distance between your power generation and utilization, or you're trying to balance load over a rather massive area.

In the area of my ignorance, though, I don't know if inductive losses would ever be significant for a superconductor. One of the defining characteristics of superconductivity is that external magnetic fields only penetrate a tiny distance (~100 nanometers) into the superconductor. I don't know if there might be a similar oddity which prevents them from generating a magnetic field outside of the conductor and coupling with other conductors.