MMP-LMHS Technology – Challenges of Superconductor Applications
What Is Missing?
Energy → Superconductivity → Technical Reliability
Potential rewards offered by the incorporation of SCs into products provide significant motivation to develop applications. The primary reason SCs are not regularly specified by application engineers is that technical reliability is absent from the initial device creation to follow on support needs. Without a focus on SC technical reliability then the new age of the SC linear media industry, above liquid helium cryogenic levels, will remain in the materials lab and the many awaiting SC device applications will not enter the commercial world.
Bulk SCs, or trapped field magnets (TFMs), have the added problem of solving the very difficult activation and deactivation technical application hurdles before allowing the move from the materials lab into a final energy systems device application. TFMs perform well in the lab but have not entered a single application due to this added problem.
Although research is underway to create SC applications with collections of discrete bulk shapes, the fundamental shape of the linear conductor offers more versatility in energy conversion and transmission applications. Linear SCs actually perform very well in the lab and in small quantities have been wound and operated in single custom device operations, but they still lack technical reliability. Technical reliability allows turning the final device manufacturing process into a quality controlled and assured process that can be trusted to repeatedly perform in the final application device. When technical reliability combines with automation and versatility then both the final system cost lowers and the variety of output types increases. Without a technically reliable system no commercial application is achievable due to a greatly increased failure rate and unpredictable failure events.
Technically reliable SCs galvanize the first machine revolution in over a century. SC wire and tape manufacturing needs span both low and high temperatures SCs (LTS & HTS). The most prominent high performance SC linear materials are MgB2 and Nb3Sn LTS wires and YBCO and BSCCO HTS tapes where each are extremely delicate and require an appropriate system for automation and technical reliability. In the LTS case one also desires handling reacted wire to remove reaction process concerns such as compromised insulation and extremely large thermal masses to support the high heat treatment.
Examples of SC Applications Awaiting the SC Revolution
Wind Turbines
In the private sector, a great example of an SC opportunity is an onshore or even more significant an offshore wind turbine where the volume and weight allowable for any wind turbine is extremely limited by what can be suspended up a tower. Conventional wire wound induction wind generators may be able to achieve ~3.5MW ratings. Permanent magnet wind generators are only recently pushing 7MW maximum ratings. SC wind turbines readily achieve 10MW offshore, as many current global initiatives require, and SC applications in Europe are even discussing 20MW SC wind turbines as recent as 2010.
Power utilities are willing to pay a premium for higher power offshore wind turbines since each part of a percent saved in power efficiency translates to extreme financial earnings over time. Via distributing the power generation across more wind turbines, all of the losses starting with power transmission are much greater than a single unit. This provides motivation to develop SC wind turbines but only if these wind turbines are reliable. The downtime for any wind turbine is an extreme financial burden. This extreme service cost is often so prohibitively expensive that wind farm operators frequently take wind turbines offline instead of servicing only a few at a time.
MRI
The Magnetic Resonance Imaging (MRI) industry, the only industrial SC application at a currently estimated $5.5B global industry and growing, relies upon the extremely low temperature requirements of SC wire at liquid helium temperatures, 4.2K. Although technical reliability is not as critical a concern with this particular SC wire type, albeit an automated technically reliable solution will certainly assist this current SC choice, the need for an MRI machine outweighed all other costs. Yet, even in the MRI industry, the objective is to replace all extremely low temperature MRI units with a higher temperature SC solution. The primary hold on this transition is again a technically reliable final machine.
Military Applications
The ultimate competition of humankind challenges societies’ scientists and engineers to produce technically superior systems. High-energy storage and high power output is often required in a very small package. This is particularly true as the U.S. armed forces continue their aim towards fewer personnel to perform a task through all electric systems. The entire U.S. armed forces, from the USAF extremely power dense and high speed generators for the all electric aircraft to the U.S. Navy all electric fleet to the U.S. Army modern armored battalions and deployable power support, all desire and in some require to enter into this SC revolution. The manufacturing of all such developing SC devices must not only provide an initial SC high power dense application design but also logistically control this specialized supply chain support need else this SC revolution will be suppressed by cost and schedule.
U.S. Navy ships for the all electric fleet experience the same technical reliability hesitation as commercial industry. A machine operating the ship propulsion and/or entire ship services power generation must be reliable. Losing power at sea can be crippling to disastrous in calm to high sea state conditions for the vessel. Yet the electric destroyer development for the U.S. Navy requires high power dense machines from ship propulsion and services to the extreme power requirements for the modern fleet high energy radars and weapon systems such as the line of sight kinetic energy railguns, exoatmospheric railguns, and high energy lasers. Losing propulsive, weapons systems, and U.S. Navy coined operational fight through power while in combat can endanger not only the vessel but also the mission which could be catastrophic on a scale much greater than the ship itself. A specific U.S. Navy example is the Zumwalt class DDG-1000 next generation destroyer propulsion system rated at 36.5MW, 6.6kV, and 120rpm capable competition where for this set power and speed rating a significant difference across three considered motor topologies was mass and volume. The propulsion power plant chosen and presently planned for deployment is the Converteam team’s based advanced induction motor concept. The DRS team proposed permanent magnet motor built and tested was reportedly around 80% of the induction machine’s mass and volume whereas the AMSC team built and tested proposed SC tape motor was reportedly 47% volume and ~30% mass of the induction machine while providing a higher efficiency. Such a leap in technology is truly revolutionary yet the AMSC team presumably lost with technical reliability of the SC tape being a primary concern.
High Field Test Magnets such as Particle Accelerators
Extreme high magnetic flux density windings include dipole, quadrupole, and higher order multipole corrector magnets for use in particle accelerators, magnetic energy storage rings, and charged particle beam transport systems. One magnetically rigorous example, as identified by global universities and national labs, is accelerator magnets. A particle accelerator loss of SCs during a full power test run can destroy large elements of the multibillion dollar accelerator system. Here not only operational magnetic field uniformity and the use of winding tension techniques to reduce the winding radial stress is crucial but the extremely high magnetic stresses, many resulting from the turn to turn as well overall coil Lorentz forces, require extremely precise and delicately handled coil builds else imperfections lead to premature fatigue.
A recent accelerator cost example was the operational cost of the second shut down of the $9B+ Large Hadron Collider (LHC) operated by CERN, the European organization for nuclear research. In the LHC NbTi SC material and not the preferred YBaCuO SC material was chosen for the single SC magnet configuration for controlling the two separate proton waves in each accelerator path section since the HTS material was deemed too fragile for the magnetic design geometries required even though use of HTS provided many other benefits. This SC choice stemmed from the knowledge that any problem leading to an accelerator shut down is prohibitively expensive in time and money. The two LHC shut downs to date for around one year each, the first caused by a faulty electrical connection to two of the LHC magnets and causing them to quench and physically rip these SCs from their mounts, cost untold $Ms each in repairs and scheduling delays besides delaying the entire mission of the LHC for which the entire global scientific community awaited an engineering resolution. There are even concerns that design flaws may not allow this machine, one of the most expensive in history, to ever operate at the designed 14TeV full collision energy capacity.
Summary of Application Examples
Each multibillion dollar application industry listed above is awaiting SC technical reliability to reduce operating costs and increase capabilities. A solution for technical reliability has now been identified.