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1 Science for a Superconductor Power Grid A. P. Malozemoff American Superconductor Corp., Devens MA USDOE BESAC Meeting Bethesda MD, July 9-10, 2009.

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Presentation on theme: "1 Science for a Superconductor Power Grid A. P. Malozemoff American Superconductor Corp., Devens MA USDOE BESAC Meeting Bethesda MD, July 9-10, 2009."— Presentation transcript:

1 1 Science for a Superconductor Power Grid A. P. Malozemoff American Superconductor Corp., Devens MA USDOE BESAC Meeting Bethesda MD, July 9-10, 2009

2 2 Superconductors - Basic Facts Superconductors discovered in 1911 - Require cryogenic cooling High Temperature Superconductors (HTS) discovered in 1986 - cuprates - 6X higher temperature (135 K vs 23 K) - Less cooling drives commercial economics Zero DC electrical resistance - Yields high electrical efficiency >100X more power capacity than copper wire of same dimensions - High power density - reduced size and weight Cooling with environmentally benign liquid nitrogen Copper, HTS @ equivalent 1000 A capacity: Power density drives system economics Revolutionizing the Way the World Uses Electricity

3 3 Superconductors: Poised for a Major Role in Addressing Key Challenges in the Power Grid superconductivity coal gas heat electrical generators electricity hydro wind fuel cells solar motors lighting. heating refrigeration information technology power grid transportation industry nuclear fission 2G wires - foundation of grid applications: cables, generators, transformers, FCLs, motors, synchronous condensers, etc.

4 US Electric Power System under Severe Stress The underlying problem: Under-investment in electric power grid while demand for electric power steadily increases Source: Cambridge Energy Research Associates 2000198019701960195019401990 6 5 4 3 2 1 0 Transmission Investment Transmission Investment US Transmission Investment (Billion $s) US Energy Consumption (Trillion BTUs) Total energy consumption Electric energy consumption Under-investment has spawned a host of technical problems Source: EIA

5 Demand growing relentlessly, doubling by 2050, tripling by 2100, plus need to reduce dependence on foreign oil 1. Need a major enhancement in overall energy efficiency Increasing grid efficiency Electrification of transportation Reurbanization 2. Need major new sources of renewable energy Power outages and disturbances cost >10B$ per year 3. Need a secure and ultra-reliable grid Environmental issues growing 4. Assure an environmentally clean energy infrastructure Grand Challenges in Electric Power

6 1. Enhancing Efficiency in the Electric Power Grid 7-10% of 1 Terawatt US electric power now lost in ac power grid - Superconductor equipment could cut this by half, save 50 Gigawatts! - Reducing delivery bottlenecks even more impactful E. g. superconductor cables bringing 50%-efficient generation to cities, replacing 30%-efficient reliability-must-run generators Dc Supergrid: a radical leap in grid efficiency - Westinghouses ac grid won out over Edisons dc grid Reduced I 2 R loss by efficient transformers, high voltage - Superconductors break this paradigm I 2 R = 0 enables high dc current, low voltage - First step: delivering renewable energy to urban centers

7 Electric vehicles ~2x more energy efficient than gas in original BTU content of oil - A 5% penetration of plug-in vehicles in Manhattan will create a 50% increase in rate of demand growth - ConEd, 11/15/05 - Superconductors key in enabling urban grids to handle this demand Maglev an efficient alternative to intracontinental aviation Military ship propulsion with HTS motors - 15% efficiency gain at half speed over conventional motors Japanese Maglev flies with HTS coils, (courtesy CJR) Enhancing Efficiency through Electrification of Transportation

8 Enhancing Efficiency by Opening the Urban Power Bottleneck Reurbanization driven by rising energy costs Requires more power capacity in dense urban areas But overhead lines near impossible to permit, underground infrastructure clogged Lower Manhattan underground infrastructure (Courtesy of Con Edison) 2003 1913 New York thenNew York now: it only gets worse!

9 Need underground power cables which are - High capacity in same X-section - Compact, light – easy to install by retrofitting existing ducts or boring - Non-interfering (no EMF or heat) - Low voltage for easy permitting Superconductors - the ideal solution! Getting Power into Our Cities 138 kV, 600 m, 574 MVA cable installed and operating since April 2008 in LIPA grid Southwire Triax TM power cable

10 San Francisco 00 Chicago 99 New Orleans 99 Atlanta 99 Delaware 99 New York 99 Detroit 00 U.S. West Coast 96 Northern California 01 U.S. Northeast 03 Denmark 03 London 03 Italy 03 Athens 04 Moscow 05 China …03, 04, 05… Establishing a Secure and Reliable Grid: an Urgent Need Significant power blackouts becoming all too frequent

11 Reliability: Controlling Fault Currents in Urban Grids Every added power source adds parallel output impedance –increases fault current In large urban grids, fault currents can exceed 60,000 A approaching maximum breaker capability! Faults short out resistive loads, leave grid primarily reactive! R ~ V I j X Need a solution, or must drastically reconfigure and break up the grid

12 Reliability: Superconductors Enable Resistive Fault Current Limiters Superconductors -smart materials, switch to resistive state above critical current Increased resistance limits current flow Many FCLs demonstrated; commercialization beginning Siemens/AMSC 2 MVA FCL Need a solution, or must drastically reconfigure and break up the gridFault current limiters a major opportunity for grid stabilization w/o FCL w/FCL

13 13 Reliability: Current Limiting Essential for Rewiring Urban Grids ConEds System of Today Powered by Copper Cables ConEds System of the Future with MV Connections Copper power cablesHTS power cables Project Hydra (AMSC/ Con Edison/Southwire/DHS) demonstrates current limiting cable

14 Renewable Energy: Opportunity for Off-shore Windpower via HTS Generators Off-shore wind - strong and steady - But only 2% of total windpower now off-shore - Opportunity to double windpower production! - Cost the obstacle Increased power rating key to economics - Systems up to 5 MW demonstrated - Above 5 MW, conventional generator simply too large and heavy HTS generators offer the needed breakthrough in size and weight to 8-10 MW - Lowest cost of energy: lowest installed cost per MW, highest efficiency, longest maintenance interval HTS generators could enable major expansion of offshore windpower

15 15 Renewable Energy: Comparison of Wind-power Generators n AMSC/TWMC ATP program addressing design and technology for 8/10 MW generator small, high power

16 Rotating Machinery: Successful Full Power Test of AMSCs 36.5 MW HTS Motor - Dec. 08 Key Advantages: Less than half the size and weight Higher efficiency Less noise Technology platform established for high power generator for wind-power 1.5MW Copper Motor 50% more power, half the weight AMSCs 36.5 MW HTS Motor 16

17 New transmission options needed to bring wind and solar energy to main US markets 17 Renewable Energy : Need to Carry 100s of Gigawatts of Green Power to Market

18 18 Renewable Energy: DC Superconductor Electricity Pipeline for Long-Length, High Power 1000-Mile, 5 gigawatt power equivalents: right-of-way advantage for HTS DC cables First DC HTS cable demonstration – Chubu U., Sumitomo Electric

19 19 The Foundation: Second Generation (2G) HTS Wires - YBCO Coated Conductors AMSC 4 cm Technology Cu, HTS power equivalents 344 superconductors cross-section Laminates – copper, stainless… Insert – substrate, buffer, YBCO AMSC wire: 4.4 mm wide, single-coat HTS wire in production – commercially available

20 20 What is Needed to Assure Major Impact and Benefit of Superconductors on Power Grid? Existing technology works, but HTS wire and refrigeration costs still limit range of application Wire figure of merit: $/kA-m - Now 200 $/kA-m ; need $25/kA-m to undercut copper - Even lower would be better! So both cost per meter and current-carrying capacity are critical - New processes to reduce wire cost - Higher critical currents At higher temperatures and fields - Higher T c ? - to decrease refrigeration load

21 21 Science Opportunities: New Superconductors Discovery of new superconductors - Track record is exciting – major discoveries every few years! - New theoretical and calculational tools, more powerful measurement tools Understanding HTS mechanism HTS cuprates - a supernova – what other supernovae await?

22 22 Science Opportunity: What Kind of New Superconductors Should We Search For? Higher T c, of course - But need to understand flux creep - thermal activation of vortices from pinning centers Reduces critical current in higher T c materials a lot! Lower anisotropy materials - Interlayer coupling dominates flux creep - Can one tune interlayer coupling of existing highly anisotropic materials? May be a more practical route to higher critical currents at higher temperature Flux creep Broaden scope of search beyond just higher T c

23 AMSC Confidential and Proprietary Field Dependence of YBCO HTS Wires – Rapid Dropoff of I c with Field, Temperature Wire Performance with Magnetic Field Perpendicular to Tape Surface Performance data courtesy Railway Technical Research Institute, Tokyo, Japan Need to increase!

24 24 Control of Grain Boundary Currents by Texturing - Key to Second Generation (2G) YBCO Wire Dimos, Chaudhari + Mannhart, PR 1990 AMSC 2G wire architecture: RABiTS TM process Texturing within ~5 0 enables J c (77 K) ~ 3x10 6 A/cm 2 over 100s of meters – An amazing success, though it has taken 18 years to get to this point! Grain boundary critical current vs misorientation angle

25 Science Opportunity: Understanding Grain Boundaries Better Grain boundaries are principal obstacle to current flow in HTS wires Contributions of in-plane and out-of-plane components still not well understood Amazing reversible behavior under compression - I c can recover from 5% of its value! - Mechanism unknown 25 D. Van der Laan, SUST 2009

26 26 Science Opportunity: Vortex Physics Pinning vortices – basis for high critical current density - Much effort on existing materials (e. g. YBCO) during last 15 years - But much still to do to increase I c Understanding magnetic pinning Interplay of columnar and planar pinning centers Flux cutting Minimizing flux creep Still significant fundamental issues in existing materials like YBCO Vortex: nanoscale quantum of magnetic flux

27 Science Opportunity: Vortex Dynamics Vortex liquid (flux flow state) - Huge area of HTS B-T phase diagram - Properties in high drive flux flow state hardly investigated, yet very important, e. g. for fault current limiters YBCO

28 28 Example: Understanding Properties of High Current Flux Flow State Kraemer et al., IEEE Trans. On Appl. Superconductivity 13, 2044 (2003) Discovery of resistance linear in voltage via quench experiment: YBCO film on sapphire In liquid nitrogen 0.1 msec after applied voltage drives film into flux flow state Resistance linear in voltage at short times!

29 29 Understanding Flux Flow State High speed photos of l N 2 bubbling reveal novel domain state in flux flow Length of quenched area increases with applied voltage - mechanism unknown Topic being addressed in Superconductivity EFRC YBCO on sapphire for three different voltages, in liquid N 2 (Kraemer et al., 2003) 50 V100 V150 V time

30 Processing Science for Superconductor Films Increasing the limiting cracking thickness for metal- organic deposition (liquid phase) processes - Key to achieving highest critical current per width need high thickness t: I c /w = J c t - During removal of organics, subtle chemical interactions and kinetics determine limiting thickness Achieving high texture in non-magnetic substrate - Texture in low stacking fault energy alloys Establishing a single-layer buffer architecture Maintaining uniform properties during film growth through precursor layer 30

31 31 Through-thickness of hybrid YBCO film - 2006 Process Science Challenge – Achieving Uniform Growth through Thick Ex-Situ HTS FilmsMulti-layerinterface Top layer has reduced texture and lower Jc AMSC MOD ex-situ films: decreased performance from poor texture across multilayer interfacesAMSC MOD ex-situ films: decreased performance from poor texture across multilayer interfaces Interface Tilted YBCO grain Lower layer has consistent texture and Jc

32 Science in Related Technologies Cost reduction of cryogenics (cryostat, refrigeration) also key - Now, refrigeration stations required at several kilometer intervals of ac HTS cable, ten kilometer for dc HTS cable - How can we achieve 10x distance between refrigeration stations? Improved MLI? Peltier effect – flush out phonons with electric current Reduced ac and dielectric losses - >1 kW pulse tube refrigerators ? 32

33 33 Conclusion Superconductivity can play major role in addressing grand challenges of energy generation, delivery and use: - Engineering foundation in place Cables, rotating machines, fault current limiters… But important issues remain for broad impact - HTS wire $/kAm and cryogenic costs Major science opportunities to address these issues - Discovery of new superconductors, HTS mechanism, increasing current density, processing breakthroughs… Support needed for a broad range of superconductor science

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