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An Introduction to Superconductivity and Its Applications in the Energy Area

Ozan Keysan

04/05/2018

keysan@metu.edu.tr http://keysan.me

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What is a Superconductor?

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Not a New Technology

Discovered before Apollo-11 (1969)

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Not a New Technology

Discovered before the first TV broadcast (1932)

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Not a New Technology

Even before Queen Elizabeth II was born (1926)

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Discovered 107 years ago!

Discovered by Heike Kamerlingh Onnes (1911)

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Race to Absolute Zero ( 0 K)

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Race to Absolute Zero ( 0 K)

They built the first cryogenics using liquid Helium

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Race to Absolute Zero ( 0 K)

Mercury’s resistivity just diminished at 4 K

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What is a Superconductor?

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Not a Rare Phenomenon

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Not Just Perfect Conductor

Perfect Diamagnetism:

Susceptibility (χ =-1), Relative permeability ( µr)=0

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Meissner Effect

Meissner effects creates the lift

Flux Pinning (Cooper Pairs) holds on balance

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Meissner Effect

Even works upside down

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R=0, so can I carry infinite current?

Unfortunately, NO

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But still, a lot of current

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Low Temperature Superconductors

  • Critical Temperatures below 30 K
  • Mostly Nb-based alloys
    • Nb-Ti (10 K)
    • Nb3Sn (18 K)
    • MgB2 (39 K, just discovered in 2001)
  • Cheap to manufacture
  • But very difficult to cool-down (requires Helium cooler)

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High Temperature Superconductors

Georg Bednorz and Alex Muller (IBM), 1987

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High Temperature Superconductors

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YBa2Cu3O7 (YBCO)

  • Yttrium Barium Copper Oxide
    • Critical Temperature: 93 K
    • Not expensive
    • Ceramic based → Brittle

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YBCO Electric Conductor Tape

Just 1% of the wire is superconductor!

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High Temperature Superconductors

  • Cooling Efficiency at 77 K: 30%
  • Cooling Efficiency at 4 K: 1%
  • N2 supplies are abundant, �Helium is quite limited
  • Specific Heat Capacity
    • Specific heat capacity at 77K is 6000 times of the capacity at 4 K

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Applications of Superconductivity

MRI Devices

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Applications of Superconductivity

MRI Devices

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Large Hadron Collider

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Large Hadron Collider

24 km ring with many magnets at 1.8 K

Thousands of tons of cold mass.

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SQUIDs

A very sensitive magnetomoter that can measure

down to (5×10−18 T)

Superconducting Quantum Interference Device

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Superconducting Machines

Mainly as ship propulsion motors

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Superconducting Machines

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Superconducting Machines

General Electric 36.5 MW

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MagLev Trains

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HTS Power Cables

Long Island, USA, 138kV

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HTS Power Cables

Suitable for dense MV distribution networks

(Maguire et al., 2007)

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HTS Power Cables

HTS AC Cables

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HTS Power Cables

HTS DC Cables

Advantages:

  • High efficiency
  • Minimized volume

Challenges:

  • Reliability
  • Fault Currents
  • Thermal Contraction
  • Energy Loss

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Why superconductors are lossless only with DC?

Under AC, normal electrons start conducting due to inductance of the cable

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Fault Current Limiters

  • High Currents should be cut of asap
  • It is possible during zero crossings in AC

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Fault Current Limiters

  • Current > Ic : Loses superconductivity (Quench)
  • Minimized Reaction Time
  • Auto-healing

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Fault Current Limiters

(YBCO) Nexans,

Germany

220 kV saturated-core FCL (Xin, Gong et al., 2012).

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The Most Important Rule of Grid

SUPPLY=DEMAND

Energy Generated = Energy Consumed

Britain Grid Control

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Grid Level Storage

Tesla's Giant Australian Battery

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Superconducting Magnetic Energy Storage (SMES)

Persistent Currents → E= ½ L I2

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Superconducting Magnetic Energy Storage (SMES)

E= ½ L I2

P= ½ B2μ0

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Superconducting Magnetic Energy Storage (SMES)

More suitable for short-term power quality issues

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Superconducting Magnetic Energy Storage (SMES)

20 MJ SMES System with HTS and LTS

(Higashikawa et al., 2007)

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Superconducting Wind Turbines

RePower Bard Turbines - 5MW - 126 m Blade Diameter

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Superconducting Wind Turbines

RePower Bard Turbines - 5MW - 126 m Blade Diameter

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Süperconducting Wind Turbines

  • AMSC, General Electric, AML
  • 10 MW, 10 rpm
  • High Torque
  • Reduced Mass

Courtesy of AMSC - GE Ecomagination

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Mass of Direct-Drive Generators

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Conclusions

  • Promising applications ahead, but:
  • Biggest Challenges:
    • Cost (both SC and cooling)
    • Reliability
    • Existing infrastructure
  • Smart Grid transformation, can be a good opportunity
  • Room temperature superconductors, one day?

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Thanks

Ozan Keysan�keysan@metu.edu.tr

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You can download

this presentation from:�keysan.me/presentations

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http://power.eee.metu.edu.tr

Superconductors: How can anything go wrong?