The New Superconductors - Proposed Applications

1. The New Superconductors - Proposed Applications Presented at IEEE Award Dinner Night New York City 5 October 2011 Dr. Swarn Kalsi Kalsi Green Power Systems, LLC Princeton, NJ 08540 skalsi@KalsiGPS.com Ph: 609-356-0600 The New Superconductors

2. Types of SuperconductorsOld and New Temperature Superconductors OLD – Low temperature (~4K) LTS NEW – High Temperature (>20K) HTS Conductor Types BSCCO-2212 – operate at 4-20K BSCCO-2223 – operate at 30 -77K YBCO-123 coated - operate at 30 -77K MgB2 - operate at 10-20K Applications All LTS applications Power cables – AC and DC Power transformers Fault current limiters Rotating machines Maglev • Conductor Types • NbTi - operate at ~4.5K • Nb3Sn – operate at ~ 4.5K • Applications • MRI • High field magnets • Particle accelerators • Fusion ….. But, they all need low cost and reliable refrigerators The New Superconductors

3. Current Status of HTS - I • High cost of HTS is the major challenge for applications in commercial devices • Rising commodity prices have adversely impacted HTS commercialization • First Generation (1G) superconductors (BSCCO-2212 and -2223) employ large quantity of silver that has seen price inflation of 5X during the last decade • Only limited performance improvements during the last 5 years • Second Generation (2G) superconductors (YBCO-123 Coated) do not employ much noble metals but have manufacturing issues • 2G materials made by plasma sputtering have better performance but are more expensive • 2G materials made by film coating have lower performance but are less expensive • However, both materials are still too expensive and a price reduction of 5-10X (from the current prices) is needed for manufacturing economically attractive devices • Manufacturers wish for more demand to drive down the price and equipment developers wish for significantly lower prices prior to prototyping new devices • Both 1G and 2G are manufactured only in tape form Courtesy AMSC Courtesy AMSC The New Superconductors

4. Current Status of HTS - II • Magnesium Diboride (MgB2) • This is the latest addition to the HTS category • Practical applications of this material are in the 5-15K temperature range • A potential feature of this material is the expected much lower cost than the 1G and 2G conductors • This material is manufactured in both rectangular tape and circular wire forms • MgB2 material is least developed and is not yet ready for application in commercial devices Courtesy HyperTech The New Superconductors

5. Cooling System • All commercial applications require low cost highly reliable cooling systems for maintaining HTS at their desired operating temperatures • Generally cost and reliability are inversely proportional to the operating temperature; i.e. lower temperature refrigerators are more expensive and require more maintenance than the higher temperature refrigerators. • Lower temperature refrigerators also require more power to remove each watt of loss from the low temperature. • Some of the possible cooling options are; • Gifford-McMahon refrigerators – available in modular form but are expensive and require frequent maintenance. • Pulse tube coolers are expected to be more reliable but are still expensive and are not available in larger sizes • Stirling coolers are expected to be most reliable and affordable but are not yet available for operating temperatures below 60K • Reverse Brayton cycle refrigerators are only economical for larger systems Courtesy Cryomech Courtesy Stirling Cryogenics The New Superconductors

6. Applications – Power Cables • Power Cable – AC and DC • Both medium and high voltage cables have been successfully prototypes and have been operating in active grid for several years • High costs of HTS and cooling system are major obstacle to wide adaption 13kV, AEP 138kV, LIPA Courtesy ULTERA Courtesy AMSC/NEXANS The New Superconductors

7. An Alternative ApproachEmploy resistive aluminum cable now and upgrade to HTS later • GE developed* an aluminum cable cooled with liquid nitrogen during the 1970s. • Because of high cost of HTS today, it may be possible to install resistive cables now and upgrade them to HTS when its price drops down to a more economical level. • Resistive cable are made using existing cable manufacturing machinery GE Resistive aluminum cable Sumitomo, Albany, NY HTS cable * S.S. Kalsi, ”Applications of HTS to Electric Power Equipment”, Wiley, 2011 Superconductor Applications

8. Applications – Power Transformer • Only 2G materials are suitable for manufacturing HTS transformers • ½ size and weight of the conventional transformers are the two key attractive features • A few prototypes are under development around the world • The biggest challenge is withstanding 2-sec short-circuit fault at the transformer terminals • Also ‘point on the wave switching scheme’ is required for minimizing in-rush transient currents Courtesy Waukesha Electric The New Superconductors

9. Applications – Fault Current Limiters (FCL) Courtesy Siemens Courtesy NEXANS • FCL take advantage of the following HTS characteristics: • Very low resistance under normal operation • Very high resistance during high current transient • Several prototypes have been built around the world but none commercialized due to the following reasons: • Sufficient time (>30sec) must be allowed following a fault clearance before re-inserting a FCL in the circuit • High costs of HTS and cooling system are still of serious concern. Coils in Series Rods in Series Saturable Reactors in Series Courtesy Zenergy The New Superconductors

10. Applications – Rotating Machines • HTS are employed only in the field winding • High field capability of HTS allows to reduce size and weight of slow speed machines by ~5X • Large machines (36MW @120-rpm) have been successfully demonstrated • Large wind turbine generators (10MW @10-rpm) employing HTS field winding are under consideration worldwide • Challenge – High costs of HTS and cooling system Courtesy AMSC 36MW motor on test bed The New Superconductors

11. Summary • Wider use of HTS superconductors in commercial devices require • Low cost superconductors • Low cost and reliable cooling systems • HTS technology is ready for large scale commercial applications Reference: ‘Applications of High Temperature Superconductors to Electric Power Equipment’, Swarn S. Kalsi, Wiley/IEEE, ISBN 978-0-470-16768-7 The New Superconductors