1. Superconductivity UK Dr. Philip Sargent, Diboride Conductors Ltd. Commercial superconductors, Cryogenics and Transformers

2. This Talk Materials Review and price predictions BSCCO MgB2 YBCO Cryogenics considerations Superconducting Transformers

3. Commercial Wire & Tape Commercial production: Niobium alloys (NbTi, Nb 3 Sn etc) B2223 / silver tape - 1 st Generation HTS Pre-commercial: MgB 2 Industrial laboratory: YBCO 2 nd Generation HTS coated conductor

4. Key issues for power applications J e Overall current density J e of conductor, not just of superconductor Performance in field Multiple filaments for AC applications Anisotropy of J c with respect to field direction Cost! Conductor itself Cooling (AC losses) Scalability of fabrication Mechanical Strength, bend radius

5. HTS –perovskite ceramics Cu OBa Y YBCO - YBa 2 Cu 3 O 7 B2223 - Bi 2 Sr 2 Ca 2 Cu 3 O

6. 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!

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

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

9. 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/cm 2 ) Superconductors typically quoted at J c 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

10. Reduced Manufacturing Costs ($/m) and Increased Wire Performance (current carrying capacity) 1995199619971998199920002001200220032004 $/kA.m 0 200 400 600 800 1000 1200 Price/Performance Ratio, $/kA-m Worlds First HTS Wire Manufacturing Plant Opened By AMSC Price/Performance $/kA.m 200 $/kA.m

11. B2223 & Commercial Products At $50/kAm (77K) price/performance ratio significant markets would be enabled (it was thought in ~1999): Utility Generators (>100MVA) Utility Generators (>100MVA) Ship Propulsion Motors and Generators (>5MW) Ship Propulsion Motors and Generators (>5MW) Wind Turbine Generators (>4MW) Wind Turbine Generators (>4MW) Urban T&D Power Cables Urban T&D Power Cables Industrial Magnetic Processing 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

12. Magnetic Field High magnetic field reduces current carrying capacity Lower temperatures enhance current carrying capacity Transformers, cables and FCLs are low magnetic field devices B2223 at 27K carries twice the current, so $/kA.m reduces to 100 $/kA.m.

13. Diboride & YBCO YBCO and similar compounds have had research worth $$billions devoted to their physics and processing. MgB 2 was discovered in January 2001; physics now entirely understood. Both can be made in: Tape geometry Massive lumps for new motor designs

14. Mg B B B Magnesium Diboride

15. Magnesium Diboride ~ 400 $/kg

16. Making Diboride tape Cu-sheathed tape transverse cross section Tube filling with MgB 2 powder Wire drawing and/or rolling Flat rolling Long lengths can be now fabricated irregular cross section Simple sintering ~700C

17. 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

18. Magnesium Diboride (MgB 2 ) Advantages No weak-link effects, low anisotropy No weak-link effects, low anisotropy Easy to fabricate wires, films: <$10/kA.m potential Easy to fabricate wires, films: <$10/kA.m potential Challenges T c < 40 K (77 K applications like cables, transformers not viable) T c < 40 K (77 K applications like cables, transformers not viable) High field applications such as NMR not viable High field applications such as NMR not viable Possible applications in 20-30K range for modest field environments, e. g., rotating machinery

19. 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 Near single crystal 100s of metres long <$10/kA.m potential, but extraordinary plant cost <$10/kA.m potential, but extraordinary plant cost

20. YBCO Ni tape Oxide buffer layer deposition

21. YBCO YBCO precursor YBCO oxygenation and conversion

22. 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 122 A (75 K) over 1 m by LANL World record for meter length World record for meter length 50 A over 10 m by Fujikura 50 A over 10 m by Fujikura World record for 10 meter length World record for 10 meter length Over 60 m :Fujikura Over 60 m :Fujikura Worlds longest processed tape Worlds longest processed tape

23. 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!

24. B2223 (1G) to YBCO (2G)

25. Reduced Manufacturing Costs ($/m) and Increased Wire Performance (current carrying capacity) 1995199619971998199920002001200220032004 $/kA.m 0 200 400 600 800 1000 1200 Price/Performance Ratio, $/kA-m Worlds First HTS Wire Manufacturing Plant Opened By AMSC Price/Performance $/kA.m 200 $/kA.m

26. ORNL Model Assumed by analogy with other fibres B2223/YBCO Wire cost ($/kA.m) Magnesium Diboride

27. Effort Performance Technology S Curves

28. Effort Performance Copper-Iron HTS g1 MgB 2 75y17y 2003 HTS g2 Power Technologies

29. Conclusions: Superconductors for AC Power HTS G1: B2223 tape Diboride: MgB 2 wire HTS G2: YBCO CC tape

30. AC Power Superconductors Higher running costs, lower wire costs Lower running costs, uses more wire Higher running costs = Higher cryogenic capital costs Higher magnetic field capability

31. Temperatures 020406080 T (K) He H Ne O N CO Liquid Phase at 1 atmosphere Cryogen Gap

32. Cryogenic Cooling Costs 30

33. Cryogenics High AC power is intrinsic to transformers Cables have high losses: so need cryogens Conduction-cooled designs need exploring 20-24K and 27K-60K for other applications Thermal reservoirs need investigating to peak-shave cryogenics capital costs Reducing the capital cost of cryogenics is as important as their efficiency for grid markets

34. Cooling & Purchase Costs There is a trade-off between cryogenic capital cost and materials capital cost – colder running means less material required but more cryogenics. The cheaper the superconductor, the higher the optimum operating temperature. Comparing different materials therefore requires a whole-system comparison Competition between materials is application dependent Transport applications are always more attractive

35. Cost Prediction Source: Mulholland et al, DOE June 2003

36. Cryogenic Patents Qi3 Limited (2003)

37. Targets Copper: 6 – 22 $/kA.m (400 to 100 A/cm 2 ) B2223: 100 $/kA.m (at 27K) Device kA/cm 2 Tesla $/kA.m Static Transformer 10 5 1.415 Cables10 5 <0.110 ? Dick Blaugher, NREL

38. ABB HTS Transformer 100 MVA, 225 / 20 kV oil free, liquid nitrogen 68K 20% lower weight 80% lower load losses 5% smaller volume Short circuit reactance 50% of conventional 25% over-loadability without accelerated ageing 150% first cost 90% lifecycle cost Short circuit current limitation in first half wave, self restoring FCL 11 m 135 000 kg 5m5m

39. Other HTS Transformer Benefits Reduced need for load tap changer units Reduced system VAR requirements Reduction in capacitor banks With a generator, reduced VAR enables additional generator capacity so reduced capital cost of generator

40. ABB Conclusions With current costs for energy and equipment, an open loop refrigeration system is the most economical. The mechanical refrigeration industry is not currently able to meet performance targets required for a commercial Utility product. –Cryocoolers are too expensive, maintenance intervals are too short, and production methods are not cost effective. –The number of competitors in the field is limited, and the companies are generally small operations. –Production scale-up and comprehensive global service could be problematic Near term market too small to justify continuation of project!

41. Waukesha/ORNL Project Waukesha 24.9kV to 4.2kV $10m project 2x overload capability FCL capability 1 MVA pilot at 25K with cryocooler

42. Transformers Lifetime Cost of Ownership in $/kW 2000 ABB SPI Phase I Analysis Cu (330 K) @ 300 A/cm 2 HTS (68 K) 200$/kAm MgB 2 (25 K) Losses60 Cryo- Wire5 Total65 5 25 50 80 510 34 5 50 Adapted from Paul Grant EPRI

43. ORNL HTS Transformer High utilization and high cryocooler efficiency required to get energy savings (RAND) Feasible with 10- year payback if <15$/kA.m at 77K. (Lawrence Assc.)

44. Energy Efficient Transformers High-copper section designs Domain-refined steels Ultra-thin iron laminations High-field (1.7T) iron alloy core Metallic glass or amorphous iron core Lowest first-cost purchasing prevents adoption of any of these technologies. www.efficient-transformers.org

45. Primary Benefit The primary benefit in a superconducting transformer is the Fault Current Limiting capability. Therefore, make FCLs first!

46. Thankyou

47. Motor images

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