DC Superconductor Cables for Long Distance Transmission 2009 Mid-America Regulatory Conference Traverse City, MI June 14-17, 2009

The challenge of moving renewable power long distances needs another option 2 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

Superconductor Electricity Pipeline The Superconductor Electricity Pipeline combines: 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 is: Underground and easy to site Highly efficient Offers greater security than other technologies Provides for multiple power on- and off-ramps

Superconductors Change the Game: 150X Increase in Power Capacity of Wires Superconductors are the high efficiency “optical fibers” of power 4

5 Siting and Security Challenges With Overhead Power Lines Courtesy Argonne National Lab

6 High Voltage AC and Long Distance Transmission… Superconductor Electricity Pipeline 765 kV Overhead Lines Power Transfer Capabilities of Old and New Technologies “Analytical Development of Loadability characteristics for EHV and UHV Transmission Lines”, Dunlop, R., Gutman, R., and Marchenko, P., IEEE Transactions on Power Apparatus and Systems, Vol.PAS-98, No.2 March/April 1979

…and Long Haul Overhead Lines Generate Heat and Waste Energy 7 Note: 765kV overhead line losses based on a variety of two and three 2400MVA SIL line designs using 4-, 6-, and 8-conductor bundles Losses for Superconductor Electricity Pipeline based on 2% DC converter losses and 35 kW/mile refrigeration losses.

New Right of Way Solution

Comparison of Transmission Alternatives Superconductor Electricity Pipelines are uniquely suited for underground, long distance, high power transmission

Superconductor Electricity Pipeline: National Loop Concept Superconductor Electricity Pipeline AC/DC Converter Stations

11/13/0811An SC-DC Cable DC Superconductor Cable 10,000MW in a 3 Foot Gas Pipe Courtesy of Electric Power Research Institute

Superconductor Electricity Pipelines 12 Installation similar to natural gas pipelines…

13 Rights of Way Already Exist for Superconductor Electricity Pipelines

Advantages of Superconductor Pipelines Underground construction with minimum right of way requirement Simplified cost allocation due to precise controllability of DC terminals Highest power capacity Highest efficiency (lowest power losses) of any transmission technology Ideal for very long distances Capable of transferring power across the three U.S. interconnections Able to accept power from multiple distributed sources, and precisely deliver power to multiple distributed destinations Minimizes interaction with existing AC grid, reducing costs and increasing operational flexibility Superconductor Electricity Pipelines are uniquely and ideally suited to move renewable energy to distant load centers

15 Comparison of a 1,000-Mile, 5 GW Run MetricDC Superconductor Cable 765KV Transmission Lines Power Loss (1) 3%Varies with design Storm/Security RiskLowHigh Precise Control for Efficient MarketsYesNo Cost Allocation MethodSimpleComplicated Requires Rebuild of Underlying GridNoYes “Black Start” CapabilityYesNo Permanent Right of Way3 ft ft. AestheticsGoodBad Electromagnetic FieldNoneHigh New Land RequiredNoYes Efficiency Savings Per Year (2) $230 millionn/a CO 2 Emission Savings Per Year (2) 3 million tonsn/a Cost Per Mile (3) $8 million for 5 GW pipe $13 million fully redundant $9-10 million minimum Performance Siting Cost (1)Cooling and converter stations for DC cable; line and substation losses for 765 kV. (2)Based on generation cost of $0.065 per kW-hr and a 100% load factor. (3)$13 million per mile cable cost based on fully redundant system. 765 kV cost does not include rebuild of underlying grid.

Superconductor Electricity Pipelines: Lots of Power, Out of Sight and Out of Harm’s Way 16