Superconductivity UK

Dr. Philip Sargent, Diboride Conductors Ltd.

Commercial superconductors, Cryogenics and Transformers

This Talk

• Materials Review and price predictions• BSCCO

• MgB2

• YBCO

• Cryogenics considerations

• Superconducting Transformers

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”

Key issues for power applications• Overall current density JJee 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

HTS –perovskite ceramics

Cu

OBa

Y

Ba

YBCO - YBa2Cu3O7B2223 - Bi2Sr2Ca2Cu3O

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!

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 Larger billets, Process automation, Longer strands, Multi-dies, Faster line-speed, strands, Multi-dies, Faster line-speed, Combination of process stepsCombination of process steps

Began volume production in early 2003Began volume production in early 2003

Full capacity could be 20,000 km/year, now Full capacity could be 20,000 km/year, now 900 km/year900 km/year

                     

• 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

Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)

Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

$/kA.m

0

200

400

600

800

1000

1200P

rice

/Per

form

ance

Rat

io, $

/kA

-m

World’s First HTS Wire Manufacturing Plant

Opened By AMSC

Price/Performance $/kA.m

200 $/kA.m

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 CablesUrban T&D Power Cables

− Industrial Magnetic ProcessingIndustrial Magnetic Processing

• Significant worldwide industry in B2223American Superconductor, Innova, Nordic Superconductor, Sumitomo American Superconductor, Innova, Nordic Superconductor, Sumitomo Electric, Vacuumschmelze, TrithorElectric, 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

• Transformers, cables and FCLs are low magnetic field devices

• B2223 at 27K carries twice the current, so $/kA.m reduces to 100 $/kA.m.

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

Mg

Mg

Mg

Mg

B

B

B

Magnesium Diboride

Magnesium Diboride

~ 400 $/kg

Making Diboride tape

Cu-sheathed tape

transverse cross section

Tube filling with MgB2 powder

Wire drawing and/or rolling

Flat rolling

Long lengths can be now fabricated

irregular cross section

Simple sintering ~700C

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 onOuter sheaths of Monel, Cu/Ni, and Cu to improve stabilization.

Hyper Tech Research

Magnesium Diboride (MgB2 )• Advantages

• No weak-link effects, low anisotropyNo weak-link effects, low anisotropy• Easy to fabricate wires, films: <$10/kA.m potentialEasy to fabricate wires, films: <$10/kA.m potential

• Challenges • TTcc < 40 K (77 K applications like cables, transformers not viable) < 40 K (77 K applications like cables, transformers not viable)• High field applications such as NMR not viableHigh 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 longNear “single crystal” 100s of metres long• <$10/kA.m potential, but extraordinary plant cost<$10/kA.m potential, but extraordinary plant cost

YBCO

                           

                               

Ni tape

Oxide buffer layer deposition

YBCO

                           

                               

YBCOprecursor

                           

                         

YBCO oxygenationand conversion

                          

                               

                             

                              

YBCO Coated Conductor tape

• Active programs in US, Japan and Europe

• Examples of results in 2001: • 122 A (75 K) over 1 m by LANL122 A (75 K) over 1 m by LANL

− World record for meter lengthWorld record for meter length

• 50 A over 10 m by Fujikura50 A over 10 m by Fujikura− World record for 10 meter lengthWorld record for 10 meter length

• Over 60 m :FujikuraOver 60 m :Fujikura− World’s longest processed tapeWorld’s longest processed tape

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)

                       

                                        

Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)

Reduced Manufacturing Costs ($/m) Reduced Manufacturing Costs ($/m) andand Increased Wire Increased Wire Performance (current carrying capacity)Performance (current carrying capacity)

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

$/kA.m

0

200

400

600

800

1000

1200P

rice

/Per

form

ance

Rat

io, $

/kA

-m

World’s First HTS Wire Manufacturing Plant

Opened By AMSC

Price/Performance $/kA.m

200 $/kA.m

ORNL Model

Assumed by analogy with other fibresB2223/YBCO Wire cost ($/kA.m)

Magnesium Diboride

Effort

Pe

rfo

rman

ce

Technology ‘S’ Curves

Effort

Pe

rfo

rman

ce

Copper-Iron

HTS g1

MgB275y 17y

2003

HTS g2

Power Technologies

Conclusions:Superconductors for AC Power

• HTS G1:• B2223 tape

• Diboride:• MgB2 wire

• HTS G2:• YBCO CC tape

AC Power Superconductors

Refigeration Energy Consumption

Carnot Thermodynamics

0 20 40 60 80

Temp (K)

En

erg

y C

on

su

mp

tio

n

Higher running costs, lower wire costs

Lower running costs,uses more wire

Higher running costs = Higher cryogenic capital costs Higher magnetic field

capability

Temperatures

0 20 40 60 80

T (K)

He

H

Ne

O

N

CO

Liquid Phase at 1 atmosphere

Cryogen Gap

Cryogenic Cooling Costs

Ideal Energy Consumption

0.00

20.00

40.00

60.00

80.00

0 20 40 60 80

Temp (K)

EC

Carnot

Sterling27K

77K

10.1x

70.4x

4K

2.9x

14x 9x

30

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

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

Cost “Prediction”

Source: Mulholland et al, DOE June 2003

Cryogenic PatentsCryogenic Cooling System patents filed in the U.S.

0

2

4

6

8

10

12

14

16

18

20

Year

Num

ber of

Pat

ents

File

d

Cryogenic Cooling System Patents

Cryocooler

Qi3 Limited (2003)

Targets

• Copper: 6 – 22 $/kA.m (400 to 100 A/cm2)• B2223: 100 $/kA.m (at 27K)

Device kA/cm2 Tesla $/kA.m

Static Transformer

105 1.4 15

Cables 105 <0.1 10 ?

Dick Blaugher, NREL

ABB HTS Transformer100 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

5 m

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

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!

Waukesha/ORNL Project

• Waukesha 24.9kV to 4.2kV

• $10m project

• 2x overload capability

• FCL capability

• 1 MVA pilot at 25K with cryocooler

TransformersLifetime Cost of Ownership in $/kW

2000 ABB SPI Phase I Analysis

Cu (330 K)@ 300 A/cm2

HTS (68 K) 200$/kAm

MgB2 (25 K)

Losses 60

Cryo -

Wire 5

Total 65

5

25

50

80

5 10

34

5

50

Adapted from Paul Grant EPRI

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.)

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

Primary Benefit

• The primary benefit in a superconducting transformer is the Fault Current Limiting capability.

• Therefore, make FCLs first!

Thankyou

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