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Wyoming Infrastructure AuthorityNovember 10, 2009

Superconductor Electricity Pipelines

The challenge of moving renewable power long distances needs another option

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Today’s Key Energy Challenge: Carrying 100’s of Gigawatts of Green Power to Market

Many Issues• Multiple Sources• Multiple Destinations• Cost Allocation• Siting• Transmission Across

Interconnections• Losses

Many Issues• Multiple Sources• Multiple Destinations• Cost Allocation• Siting• Transmission Across

Interconnections• Losses

A New Transmission Option

Combine:• Conventional underground pipeline construction

With two power system technologies:• Superconductor cables• Reduced voltage multi-terminal DC power transmission

The result:• A high capacity electric transmission “pipeline” that offers

a new option for connecting diffuse sources of renewable power to remote load centers in a controlled mannerUnderground and easy to siteHighly efficientCost competitive with currently available options Offers underground security and siting advantages

Superconductor Advantages with DC Power

• When carrying DC current, superconductors themselves are perfectly lossless- Regardless of length - Regardless of power rating

• Benefits- No power limitations based on current-based losses- Allows lower voltage, higher current transmission- Allows underground construction

Superconductors drive the economics of this transmission option

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Superconductor Cables Projects Around the World

2001 2002199919981997 2010 2011 201320122000 2009200820072006200520042003

US/Nat. Grid – 34.5kV (400m)

US/DTE – 24kV (120m)

JAPAN – 77kV (500m)

US/EPRI – 115kV (50m)

SPAIN – 10kV (30m)

US/AEP – 13.8 kV (200m)

DENMARK – 36kV (30m)

CHINA – 35kV (30m)

JAPAN – 66kV (30M)

CHINA – 10.5kV (75m)

US/Southwire – 12.5kV (30m)

US/LIPA Phase I – 138kV (600m)

KOREA – 22.9kV (100m)

MEXICO – 15kV (30m)

CHINA – 110 kV (30m)

KOREA – 22.9kV (100m)

RUSSIA – 35 kV (30m)

KOREA – 22.9kV (30m)

US/ENTERGY – 13.8 kV (1,600m)

JAPAN – 66kV (250m)

CHINA – 35 kV (30m)

US/ConEd – 13.8 kV (220m)

US/LIPA Phase II – 138 kV (600m)

KOREA/KEPCO – 154 kV (500m)

AMSTERDAM – NUON (6,000m)

SPAIN – 20kV (30m)

RUSSIA – 35kV (100m)

Superconductor wire and cables are available from a variety of manufacturers around the world

Transmission Level Superconductor Cable

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Application of established AC superconductor cable technology to DC is straightforward

• Location; Holbrook, NY (Long Island)

• 138kV, 2400A, 600m, 575MVA, single phase cables

• In service since April 2008

Figures courtesy Nexans

VSC HVDC Terminals

• Voltage Source Converter (VSC) based HVDC terminals available from multiple manufacturers

• Advantages of VSC converter topology:- Allows incorporation of multiple DC terminals on a

line- Greater control and flexibility- Allows the DC line to be envisioned as a DC bus

• VSC converter available only at lower voltages requiring higher currents- Voltage drop- Losses

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AC Overhead Transmission

• Higher power and longer distances require higher voltages

• Losses

• Limited power flow control

• Power transmission characteristics

• Public opposition

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Transfer Capability Versus Distance of a 765 kV Overhead Line

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5GW of Renewable Energy Transmission

Range of Losses for Various 765kV Overhead Line Designs

Courtesy Argonne National Lab

Dominant form of transmission, but many challenges

DC Superconductor Cable

10,000MW in a <1m Gas Pipe

Courtesy of Electric Power Research Institute

Superconductor ampacity has little to no impact on cable dimensions

Operational Opportunities for DC Superconductor Cables: ELECTRICAL EFFICIENCY

• Overall losses 2.75% for 5GW @1000 miles (2.4% for 10GW)

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Losses for 5GW Transmission

765kV OH, 2 Lines

765kV OH, 3 Lines

+/-300kV Underground DC [6]

Overhead +/-800kV DC [7]

+/-200kV Superconductor Pipeline

Optimized 765kV, 3 Lines [8]

Loss advantage increases with distance and MW rating

Operational Opportunities for DC Superconductor Cables: SIMPLIFIED SITING AND ROW

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• Underground installation addresses public and environmental concerns

• One pipeline can replace many overhead lines

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Operational Opportunities for DC Superconductor Cables: SIMPLIFIED SITING AND ROW

Co-location along existing right-of-way may simplify costly and complex siting procedures

Operational Opportunities for DC Superconductor Cables: GRID OPERATIONS

Enhanced Grid Operation and Market Dynamics- Networked DC terminals allow aggregation of

renewable sources (wind/solar) reducing variability- Opportunity for ancillary services including regulation,

spinning reserve, etc

Reduced Impact on Underlying Grid- Largely decoupled from underlying AC grid- Control over DC system interaction with AC grid during

faults- Provides long distance wheeling without impacting

regional grids

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Operational Opportunities for DC Superconductor Cables: Redundancy

• Redundant cables can provide single line redundancy

• Loop networks, like EHV overlays, provide inherent redundancy 14

Cost Analysis

• 5GW, 1000mile Superconductor DC Cable System- US$8 M/mile- Costs include DC terminals, refrigeration, installation- Doubling capacity to 10GW line increases cost by less

than 1/3

• Cost Competitive with EHV AC- US$2.5 - $5.5 Million/mile per line- 2 to 3 lines needed for same capacity

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Long distance, high power superconductor DC cables are cost competitive with EHV AC lines

Tres Amigas SuperStation Project

Western Interconnection

Eastern Interconnection

Texas Interconnection

14,400 square acres (22.5 sq. miles) of land in Clovis , New Mexico already allocated for project

Tres Amigas Project to Use Superconductor Electricity Pipeline

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Lots of Power, Out of Sight and Easy to Site