Superconducting power systems
Our work on ultra-efficient aircraft, wind turbines, flywheels and transformers is helping to reduce energy waste and creating renewable energy solutions.
Superconducting technology applications in electric machines provide higher efficiency and power density over conventional technology. This means that superconducting power systems can be smaller and lighter, while still providing the same power output. Robinson Research Institute's (RRI) expertise in High Temperature superconductor (HTS) science and engineering has resulted in our involvement in several extremely exciting international collaborations across a range of superconducting power system applications. Our work on ultra-efficient aircraft, wind turbines, flywheels and transformers is helping to reduce energy waste and paving the way to renewable energy solutions.
Electric engines for aircraft
Combatting greenhouse emissions and rising fuel costs in aviation poses a significant challenge because commercial aircraft have very-high power propulsion systems, which are subject to stringent weight constraints. These weight constraints mean that hybrid-electric aircraft will require advanced motors and generators with power densities that exceed the capacity of conventional copper and iron machines.
NASA's Electric Aircraft Technology Roadmap has identified that the only feasible solution is to employ superconducting high-speed motors, electrically driven from an optimised turbo-generator. NASA has drawn RRI into the international effort to develop hybrid electric aircraft because of our international reputation for superconductor science and engineering. Together with our partners at Beijing Jiaotong University we are developing a superconducting electrical induction motor and cooling system for use in aircraft which will be half the weight of a conventional jet engine.
HTS flywheels for energy storage
Beijing subway is the largest electricity user in Beijing. Currently, a great deal of energy is expended in braking and accelerating trains. By capturing and reusing this energy with an HTS flywheel we estimate that it will be possible to save as much as 40 percent of the energy used by the Beijing subway system.
The HTS flywheel is effectively an energy storage device. When trains slow down to stop at stations the flywheel will store the train’s kinetic energy and can later supply it back to them to help with take-off. This energy storage system not only represents the potential for energy saving in subway systems but also in supporting renewable energy generation. The same technology can be used to store energy generated by solar or wind, so in periods of low-energy production a store can be tapped into as needed.
RRI has completed an HTS flywheel design, and we are now working alongside Beijing Milestone Superconductor Technologies in a new venture with Victoria University of Wellington ‘Wei Mei’. Using our links with Beijing Jiaotong University, we are seeking to take this to the next stage with Beijing Subway Operations Limited.
Lighter, more powerful wind turbines
To make wind power into an economically viable alternative to fossil duels it is necessary to exploit the largely untapped resource of offshore wind energy. Although initial costs for large offshore turbines are higher, these costs can be recouped by higher energy yields because offshore wind conditions are more favourable.
Superconducting technology will be a key enabler of offshore wind energy growth. The increase in power density provided by innovative superconducting turbines will significantly reduce generator weight, reducing the cost of towers and foundations, and maximize the power output per tower.
As part of an international collaboration lead by the Inner Mongolia University of Science and Technology RRI are developing HTS generators for use in a wind turbine research and development project for the National Natural Science Foundation of China (NSFC). Our expertise in HTS science and engineering will allow us to build 12 MW class turbines at a lower weight than existing 8 MW class turbines.
Superconducting distribution transformers to reduce energy loss
Transformers are an integral part of the electricity transmission and distribution network, stepping up voltage for long distance transmission and stepping voltage down again for consumer use. Conventional transformers are made of windings of copper or aluminium wire immersed in an oil coolant. Novel transformer designs using HTS wire immersed in liquid nitrogen are smaller, lighter, and more efficient that conventional transformers, and eliminate the pollution and fire hazards of oil coolants.
In 2013, the Robinson Research Institute and its Australasian partners designed, built, and tested a three phase 1 MVA 11 kV/400 V HTS transformer. The low voltage winding made from YBCO Roebel cable achieved a current rating of 1400 A, which is the highest ever demonstrated in an HTS transformer. Coupled with a high-efficiency cryocooler this transformer would have half the load losses of a conventional transformer of this rating.
In 2017 Robinson Research Institute successfully tested a 45 kVA fault current limiting HTS transformer. This single phase demonstrator limited the short circuit fault current to only three times the rated current of 100 A, withstood the fault for longer than 1 second, and cooled down again within a few seconds while carrying close to rated current. This unique fault current limiting capability of HTS transformers can be of great value in situations where more power generation needs to be added to a network already near the limit of its fault current protection system.
The world‘s demand for electricity is increasingly driven by the shift from fossil fuels, a growing variability in supply from integration of renewables generation, and growing peaks in usage. Significant investment in advanced electricity networks will be needed in order to manage these changes, with Western Europe alone expected to invest $133.7 billion in smart grid infrastructure through 2027. Our work at Robinson has shown that HTS transformers can be a commercially attractive solution that will reduce energy losses, improve network fault tolerance, improve safety, and increase power density within switch yards.
Lightweight traction transformers
RRI is working on a project with China Railroad Construction (CRRC) and Beijiing Jiaotong University to develop a superconducting traction transformer for high speed trains. By incorporating HTS technology into the design we hope to reduce the weight of the transformer by 30 percent, an improvement which could lead to greater passenger carrying capacity or speed increases.