Commercial superconductors for motors and generators Superconductivity UK Commercial superconductors for motors and generators Dr. Philip Sargent, Diboride Conductors Ltd.

Commercial Wire & Tape Commercial production: Niobium alloys (NbTi, Nb3Sn etc) B2223 / silver tape - 1st Generation HTS Pre-commercial: MgB2 Industrial laboratory: YBCO 2nd Generation HTS “coated conductor”

Superconductors 1910 1930 1950 1970 1990 20 40 60 80 100 120 140 160 Liquid Nitrogen (77K) Liquid Methane LNG (112K) (La, Ba) Cu) HgBa2Ca2Cu3O9 (under pressure) TlBaCaCuO B2223 - Bi2Sr2Ca2Cu3O YBCO - YBa2Cu3O7 Tl, Hg…(138K) Transition temperature (K) MgB2 V3Si Nb3Sn Nb3Ge NbC NbN Hg Pb Nb Leigh Jarvis

More superconductors YPd2B2C HoMo6S8 (Chevrel) ErRh4B4 CeRu2 heavy fermion 1991 - K3C60 Fullerene 1994 - Sr2RuO4 2001 – MgB2 2001- C nanotubes 2002 - PuCoGa5 (18K) 1980- (TMTSF)2PF6 Nature 6 Mar.2003 - Na0.35CoO2•1.3H2O

HTS –complex copper oxides                                                                 B2223 - Bi2Sr2Ca2Cu3O YBCO - YBa2Cu3O7

HTS –perovskite ceramics Cu O Ba Y B2223 - Bi2Sr2Ca2Cu3O YBCO - YBa2Cu3O7

Engineering Implications Requires near single-crystal microstructure by complex processing, Oxide requires furnace treatment in controlled oxygen atmosphere, in silver, Highly anisotropic resulting tape: Along and across tape, Sensitive to magnetic field direction!

B2223 multifilamentary tape -1                                              Fill silver tube with precursor powders. Reduce by extrusion, swaging, drawing and rolling to a mono-filament aligned-crystal wire. Restack bundle in another silver tube.                                                                                     

B2223 multifilamentary tape -2 Draw multifilament Draw to align crystals Roll to tape Furnace heat treat

American Superconductor 55 filament (B2223) tape AMSC & Sumitomo AMSC & Sumitomo have a reciprocal licensing agreement American Superconductor 55 filament (B2223) tape Sumitomo (B2223) tape

AMSC B2223 Manufacturing Plant                       Larger billets, Process automation, Longer strands, Multi-dies, Faster line-speed, Combination of process steps Began volume production in early 2003 Full capacity could be 20,000 km/year, now 900 km/year

(B2223) Critical Currents 2001-02 Manufacturing variability 32 30 > 150 m lengths Manufacturing Campaign for Detroit Edison Manufacturing Campaign for Customer X (2002) 28 26 24 22 20 18 Frequency 16 14 12 10 8 6 4 2 100 103 105 108 110 113 115 118 120 123 125 128 130 133 135 138 140 143 145 148 150 End to End Critical Current, Amps 170 A also demonstrated in short lengths

B2223 Wire Improvement Measured at AMSC & UW University of Wisconsin 21 Measured at AMSC and University of Wisconsin Measured at AMSC & UW University of Wisconsin 20 19 18 17 Jc (A/cm2, 77 K, 0.1T, //c) 16 15 14 13 12 1994 1995 1996 1997 1998 1999 2000 2001 2002 Jc of 19.8kA/cm2 (77K, 0.1T, //c): a new level of performance for wire with production architecture Measurement in 0.1 T field avoids self-field current suppression

Current Distributions in B2223 180 kA/cm2 Regions Observed in AMSC Monocore Tapes Headroom for Further Current Density Progress (U. Wisconsin/AMSC)

AMSC B2223 Plant History Development started in summer 1988 10 years (1998): AMSC produces 20 km in 200 m lengths with an average current of 90 A at 77 K 14 years: 900km/y plant fully operational 15 years: 900km/y plant & B2223 IPR value of $22m written off !

Price/Performance $/kA.m How much does it cost to buy the wire to carry 1000 Amps a distance of 1m? Copper: 6 $/kA.m – 22 $/kA.m depending on current density (400 – 100 A/cm2) Superconductors typically quoted at Jc and at 77K and either zero magnetic field or “self field”. Cryogenic OFHC copper can be 0.06 $/kA.m. NbTi is approx. 0.9 $/kA.m in liquid helium.

Price/Performance $/kA.m 1200 $/kA.m 1000 800 Price/Performance Ratio, $/kA-m 600 World’s First HTS Wire Manufacturing Plant Opened By AMSC 400 200 200 $/kA.m 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Reduced Manufacturing Costs ($/m) and Increased Wire Performance (current carrying capacity)

B2223 & Commercial Products At $50/kAm (77K) price/performance ratio significant markets would be enabled (it was thought in ~1999): Utility Generators (>100MVA) Ship Propulsion Motors and Generators (>5MW) Wind Turbine Generators (>4MW) Urban T&D Power Cables Industrial Magnetic Processing Significant worldwide industry in B2223 American Superconductor, Innova, Nordic Superconductor, Sumitomo Electric, Vacuumschmelze, Trithor Bought and shut down by AMSC in 2002

Magnetic Field High magnetic field reduces current carrying capacity Lower temperatures enhance current carrying capacity B2223 must operate 20K – 40K for motors which have fields ~ 2T B2223 at 27K carries twice the current, so $/kA.m reduces to 100 $/kA.m.

Saturation in Fe-3%Si at 1.6T Flux Density, B (T)

1.6T Power Apps 30 – 77 K Copper: up to 400 A/cm2 MA/cm2 Peter Lee’s Cosmic Plot (UW/ASC) 10 1.6T 1 Power Apps 30 – 77 K 0.1 Copper: up to 400 A/cm2 0.01 0.001

Key issues for power applications Overall current density Je of conductor, not just of superconductor Performance in field Multiple filaments for AC applications Anisotropy of Jc with respect to field direction Cost! Conductor itself Cooling (AC losses) Scalability of fabrication Mechanical Strength, bend radius Conductor shape tape or wire or new motor designs

Diboride & YBCO YBCO and similar compounds have had research worth $$billions devoted to their physics and processing. MgB2 was discovered in January 2001; physics now entirely understood. Both can be made in: Tape geometry Massive lumps for new motor designs

Magnesium Diboride Mg B s 39K p

Magnesium Diboride ~ 400 $/kg

Making Diboride tape Simple sintering ~700C Cu-sheathed tape transverse cross section Tube filling with MgB2 reacted powders Wire drawing and/or rolling Flat rolling Long lengths can be now fabricated irregular cross section Simple sintering ~700C

+ PIT Processing routes for the fabrication of MgB2 wires tube filling B Mg IN-SITU a) + MgB2 EX-SITU b) draw to wire simple sintering reaction sintering 23% porosity 100m lengths of tape IN-SITU EX-SITU

Powder in Tube Université de Genève Final Tape Flat rolling P.I.T. Ball milling under Ar P. I. T. Swege Draw Flat rolling Fin= 5 mm Fout= 8 mm F = 3.85 mm F = 2 mm Tape 4 x 0.38 mm2 P.I.T. Final Tape MgB2 Flat rolling Université de Genève

HyperTech CTFF for MgB2 CONTINUOUS TUBE FORMING AND FILLING (CTFF)

Irreversibility field L. Cowey et al., MgB2 + yttria Increase magnetic field capability by metallurgy Create pinning defects by controlled alloying of MgB2

10-Meter Long Square MgB2 Wire Texas Center for Superconductivity and Advanced Materials University of Houston NASA Commercial Space Center CSAM T 10-Meter Long Square MgB2 Wire

Strain Effect on MgB2 long tape 100 h ball milled Strain gauges Modified Walters Spiral (WASP) MgB2 Tape d=26 cm Université de Genève

In situ B+Mg with Fe barrier in Monel Sheath With iron –tough to make multifilament- most likely be cabled , (twisted) monofilaments for low AC loss conductor, working on Outer sheaths of Monel, Cu/Ni, and Cu to improve stabilization. Hyper Tech Research

Reasonable properties can be obtained with all Cu wires, Or with with Nb barriers in Cu. Multifilament wires can be made Hyper Tech Research

Shows ITER barrel wound with over 1 meter of MgB2 wire, all Cu sheath, 1.00 mm diameter wire. The self field transport current for the coil at 4.2 K was 450 amps, the estimated transport current at 20 K would be 150-180 amps. Hyper Tech Research

First test of an MgB2 pancake BSCCO 250 MgB pancake 2 BSCCO pancake MgB2 200 150 4.2 K Critical Current [A] 100 50 3.0 3.5 4.0 4.5 5.0 Magnetic Field [T]

Genoa 25 K Power Apps 30 – 77 K Peter Lee’s Cosmic Plot (UW/ASC) MA/cm2 Peter Lee’s Cosmic Plot (UW/ASC) 10 1 Genoa 25 K Power Apps 30 – 77 K 0.1 0.01 0.001

Magnesium Diboride (MgB2 ) Advantages No weak-link effects, low anisotropy Easy to fabricate wires, films: <$10/kA.m potential Challenges Tc < 40 K (77 K applications like cables, transformers not viable) High field applications such as NMR not viable Possible applications in 20-30K range for modest field environments, e. g., rotating machinery

YBCO Coated Conductor Rolled, textured Nickel tape (Ni-W) Oxide buffer layer, preserves texture YBCO (or analogue, e.g. HoBCO), preserves texture Near “single crystal” 100s of metres long <$10/kA.m potential

YBCO Coated Conductor Sumitomo YBCO-CC

YBCO                                                            Ni tape Oxide buffer layer deposition

YBCO                                                                                                                                                                                                                                       YBCO precursor YBCO oxygenation and conversion

YBCO                                                                                                                                                                                                                                                                                               Slitting

YBCO Coated Conductor tape Active programs in US, Japan and Europe Examples of results in 2001: 122 A (75 K) over 1 m by LANL World record for meter length 50 A over 10 m by Fujikura World record for 10 meter length Over 60 m :Fujikura World’s longest processed tape

Comparative Development YBCO CC Fujikura announces YSZ-IBAD process, early 1991 Ten years later (2001): Fujikura produces 10 m with 50 A (77 K) B2223 Work started in summer 1988 Ten years later (1998): AMSC produces 20 km at minimum 200 m piece length with an average current of 90 A (engineering current density 11,000 A/cm2 at 77 K)

YBCO CC Technical Issues Adequate uniformity over length Stability to over-currents or cracks Adequate current in MOD films Mechanical properties – spalling, cracking Stability of metal-oxide epitaxial interface Deposition rate for ion beam and laser processes Thicker than 3 micron YBCO ? …but must have that 10 $/kA.m process!

B2223 (1G) to YBCO (2G)                                                                

Price/Performance $/kA.m 1200 $/kA.m 1000 800 Price/Performance Ratio, $/kA-m 600 World’s First HTS Wire Manufacturing Plant Opened By AMSC 400 200 200 $/kA.m 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Reduced Manufacturing Costs ($/m) and Increased Wire Performance (current carrying capacity)

AMSC 2G Plant 25th Sept. 2003 1st October 2003 3rd October 2003 ORNL award of $2.5m to AMSC to commercialise 2G process 1st October 2003 First tranche of $10m from US DoD and DOE to build 2G plant for YBCO-CC tape over 3 years. 3rd October 2003 $44m share issue priced to be used to build 2G plant but all committed on pre-commercial processes!

Technology ‘S’ Curves Effort Performance

Power Technologies HTS g2 75y 17y MgB2 Performance HTS g1 Copper-Iron 2003 Effort

Conclusions: Superconductors for Motors HTS G1: B2223 tape Diboride: MgB2 wire MgB2 HIPped bars HTS G2: YBCO CC tape YBCO cast crystals