Long considered a lab experiment, superconductivity has been implemented on a production scale for the first time in a spectacular project: a 600-meter, 138-kV underground cable was installed in New York City to transmit triphase current without heat dissipation or line losses. This feat was made possible by a so-called “high temperature” superconducting cable (-200 °C, compared with absolute zero of -273 °C) made with bismuth and cooled with liquid nitrogen in an airtight sheath. The cable can transmit three times more electricity than an equivalent copper cable. But the prohibitive cost of this technology confines it to high-density urban environments requiring large quantities of power (New York City has one of the highest concentrations of air conditioning units in the world), where the cost of real estate is highest.