The key to "superconducting power transmission" - the technical development of transmission cables has basically ended. Transmission power loss will be accompanied by the use of superconducting power and dropped. Commercial operation will start within 5 years. As an energy saver, this technology will also play a role in long-range power coordination across borders. Research began more than 20 years ago, "superconducting transmission" has finally entered the final stage of practical. The so-called superconductivity refers to the phenomenon that the resistance becomes zero when the specific metal or compound is cooled to the ultra-low temperature. The superconducting cable is the cable made using this technology is made of insulated tubes in the cable. Insulation pipe into the liquid nitrogen and other refrigerants to maintain the required low temperature superconducting state, this power transmission loss is much lower than the average copper. In Japan, the total generating capacity in FY2011 was 857.4 billion kwh, of which about 5% was lost on the way from the power station to households, equivalent to one year of power generation of six 1,000,000-kilowatt nuclear power plants. Data show that wire resistance The loss is about half. Because of this, people are full of expectations for zero-resistance superconducting cables. "Superconducting" drive tram The Institute of Railway Integrated Technology, located in Kokubunji City, Tokyo, commonly known as "Railway Comprehensive Research Institute". In the experimental track laid in the Institute, running a genuine tram. Next to the track, a black cable of about 31 m in length is installed. This is the superconducting cable for power transmission. The superconducting cable developed by the Railway Research Institute supports DC transmission, and the superconducting material wire made of a rare metal bismuth is packaged in a tube of about 10 cm in thickness. At work, liquid nitrogen at -196 ° C circulates internally, cooling the wire to zero the resistance. Because superconducting transmission needs to circulate liquid nitrogen, it is common practice to set up two parallel cables in parallel. However, taking into account the freedom of remote use and set-up, Railway Research Institute adopts a multi-layer insulation tube to design a structure that allows liquid nitrogen to travel back and forth in a single insulated tube. "It is not just cutting power transmission losses. Superconducting cables are also effective for the efficient use of renewable energy sources," said Dr. Tomita Tomita, minister and director of the Superconducting Applications Research Laboratory at Railroad Research Institute. In the tram parking, the motor generator to play the role of kinetic energy into electrical energy recovery, which is renewable energy. In the future, renewable energy will be able to be transmitted over wires to other trams. Now, due to the large resistance of the transmission line, renewable energy can only be supplied to nearby trams. The use of superconducting cables, in principle, no matter where the tram, can exchange power. Tomita calculations, "If the railway, energy-saving effect will reach 5%." Performance testing using 31m cables is now almost complete. The world's first verification experiment to power vehicles using superconducting cables began in June. As scheduled, a full verification experiment using a 310m cable will begin in the fall. Tomita confidently said: "This experiment will be a major breakthrough with the goal of using it in the actual railway network." Practical is expected to be achieved in 5 to 10 years. Japan took the lead in mass production of cables Ishikura City, Hokkaido is also promoting the use of superconducting cables transmission project. Location is Ishikari Bay Newport area. In accordance with the project plan, solar panels will be produced in the form of DC power through the 500m long superconducting cables, to the IKURAInternet Ishima data center. Power transmission is scheduled to begin within 2 years. After 2014, the city will re-install the 2km long cable to verify the power loss and maintenance costs of the long-distance transmission. There is a huge demand for electricity because of the large number of servers running in the data center and the need for cooling. Efficient use of electricity helps to significantly reduce operating costs. This time, the power consumption of Ishigat's data center has been reduced to less than half its current level with the aid of cold weather and direct current. For experimental purposes, Professor Taro Yamaguchi, a professor at the Superconducting and Sustainable Energy Research Center at Chubu University, which plays a central role in the project, said: "Solar power can be efficiently utilized by combining superconducting power transmission." Humans found that superconductivity dates back to 1911, more than 100 years ago. However, the superconductor that was originally discovered must reach the superconducting state when the temperature drops to near zero (-273.15 degrees). Cooling requires the use of expensive liquid helium, which is hard to apply to power transmission. However, as "high-temperature superconductors" that reach superconductivity at higher temperatures were successfully developed in 1986, the development of superconducting cables has been flourishing. HTS includes many types. For example, the use of rare metal bismuth superconductivity is reached at about -160 degrees superconducting state. Superconducting materials that use rare earth yttrium and also reach superconducting states at -180 degrees have also been developed. Cooling these superconductors can use liquid nitrogen that is warmer than liquid helium, but much cheaper and easier to store. Because high-temperature superconductors can be used steadily, the value of commercial use has gradually emerged. Sumitomo Electric Industry Superconducting Product Development Minister Lin He said: "Cable performance has reached a practical level." In the superconducting cable production technology, the Japanese companies located in the forefront of the world. Sumitomo Electric Industries is a pioneer among Japanese companies. In 2003, the company took the lead in successfully mass-producing HTS cable materials worldwide. Supply of wire and cable made of bismuth to many superconducting power transmission experiments at home and abroad. On the other hand, Furukawa Electric Industries, Fujikura and other Japanese wire companies developed yttrium-based cables. The view is that yttrium-based cable silver less cost advantage, but in terms of mass production technology, bismuth in the lead, from the recent practical. Although superconducting cables can help save energy, it is not a panacea. The superconducting cable's resistance is indeed zero, but maintaining the superconducting state requires constant cooling of the liquid nitrogen during its circulation, which requires the use of freezers and pumps. Refrigerators and pumps consume electricity, so strictly speaking, transmission losses are not zero. At present, the transmission loss of large-scale power transmission to large facilities with large power consumption will be the main use of superconducting transmission. In the future, with the development of high-efficiency freezers, the range of applications will be expanded in one fell swoop. In addition, DC transmission is a priority for the rail and data center examples described above.