First in the World Prototype of Hydrogen 
Superconducting Transport System Has Been Tested

V.S. Vysotsky, A.A.Nosov, S.S.Fetisov, G.G.Svalov
Russian Scientific R&D Cable Institute

V.V. Kostyuk 
Russian Academy of Science

E.V. Blagov
Institute of Nanotechnology and Microelectronics of the 
Russian Academy of Sciences

I.V. Antyukhov, V.P. Firsov
Moscow Aviation Institute – Technical University

November 26, 2011 (HP43).  Most of the renewable energy production facilities are situated in suitably chosen areas of substantial size, which are often located far away from densely populated areas. Therefore, new solutions have to be found to develop high-power electric transport grids, capable of carrying energy over long distances.

An interesting development that was recently discussed at IASS [1] is the replacement of standard HVDC with DC superconducting line, particularly by use of new HTS or MgB₂ superconductors. In spite of its recent discovery, MgB₂ has already shown its full potential as a superconductor which may represent a logical step of evolution in the upcoming years for most of the applications. It was concluded in [1] that MgB₂ with single phase liquid hydrogen with or even without additional single phase N₂ coolant offers major simplifications with respect to classic Nb-alloys and boiling He + N₂ , with practical distances of up to several hundred km.

The joint team of Russian researchers developed and tested the first prototype of the future hybrid hydrogen and superconducting energy transport system. The team includes Russian Academy of Science (RAS - general management) –, Russian Scientific R&D Cable Institute (VNIIKP – MgB₂ cable development) and Moscow Aviation Institute – Technical University (MAI – hydrogen cryogenic system development).

The hybrid system consists of hydrogen transfer cryostat with 12 m length provided by current leads with rated current up to 3-4kA. Inner diameter of the cryostat is 40 mm with the outer diameter of 80 mm and vacuum superinsulation between walls. No liquid nitrogen precooling has been used in the cryostat.

The power cable has been developed based on MgB₂ superconducting wire from Columbus superconductor, Genova, Italy. The wire has 3.65 mm x 0.65 mm size with 12 MgB₂ filaments and Cu central stabilizer in Ni matrix [2]. Five tapes were used in the cable design, twisted around copper bunch protected superconductor against fault. The copper bunch was placed around central stainless steel spiral with inner diameter 12 mm. Outer diameter of the cable was 28 mm.

The transport system has been tested at the special test facility by filling of liquid hydrogen from a storage tank. The flow rate of hydrogen was from 2 to 7 g/sec under pressure from 0.15 to 0.45 MPa. Temperature variations were from 20 to 26 K during experiments. Voltage – current characteristics of the cable were measured at different temperatures and critical currents by 1 µV/cm criterion have been determined. At 20 K, the critical current of the cable was more than 2600 A and at 26 K more than 2000 A. It means the superconducting properties of MgB₂ superconductor are good enough for use in high-current power cables.

These results are the first experimental demonstration the feasibility of high power energy transport systems were energy is transferred by both: liquid hydrogen and electricity.

References

[1]  C. Rubbia, “The future of large power electric transmission”, available at: 
       http://www.iass-potsdam.de/fileadmin/user_upload/Rubbia_presentation.pdf 
[2]  Columbus Superconductor SpA, available at: 
       http://www.columbussuperconductors.com/mgb2.htm