Superconducting magnetic storage

Energy held in the magnetic field of a superconducting coil.

Storage · Electrical and system · No. 93

• Storage
• Duration: Seconds

Current can circle a superconducting coil almost forever with no loss, ready to release its energy in about 5 milliseconds.

Chart: Illustration: Superconducting magnetic storage

Where it comes from

Chart: Map of where it comes from

Wire made of niobium alloys or rare-earth tape loses all resistance when chilled, so current circulates and stores energy in the magnetic field.

Three things to know

1. At 10 tesla a magnetic field holds only about 11 kWh per cubic metre, so SMES stores little energy.
2. Cooling to 4 K costs at least 74 W of input for every watt removed, even for an ideal refrigerator (calculated).
3. Superconducting tape cost USD 150 to 200/kA-m in 2023, against USD 50 seen as the tipping point for power uses.

The journey

1. 1 DC powerDriven into a superconducting coil
2. 2 Deep coldCoil cooled to between 4 and 77 K
3. 3 Circulating currentFlows with almost no resistance
4. 4 ConverterDraws current out in milliseconds
5. 5 GridVoltage support and power quality

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