Japan’s Railway Technical Research Institute (RTRI) has developed a new superconducting power transmission technology that promises zero transmission loss.
The 1.5-km superconducting transmission line – the world’s longest practical-use cable – at a facility in Miyazaki Prefecture, offers a potentially less costly way to operate trains and acts as a possible countermeasure to global warming.
Mitsui Mining & Smelting was tasked with producing this new line, and several railroad companies have already shown interest in adopting this new technology, reports the Nikkei Asian Review.
Transmission loss is mainly caused when electricity turns into heat due to the electrical resistance of electric wires.
Reducing this would prove significant as Japan loses 4% of its electricity as it is being delivered, reports the Institute of Energy Economics.
The country’s railways alone use about 17 billion kilowatt-hours a year, and 4% of that is about 700 million kilowatt-hours, equivalent to what 160,000 ordinary households require.
When a transmission line is cooled to minus 269°C with liquid helium and put into a superconducting state, the electrical resistance becomes zero, and power loss can be all but eliminated.
One reason why it hasn’t been adopted so far is the technology’s cost. But thanks to the development of materials that can be superconducting at minus 196°C, liquid nitrogen can be used as a coolant, which is 10% cheaper than the standard liquid helium.
RTRI has taken this less expensive coolant, innovated with it and discovered a way to coat transmission lines with it.
According to the institute, the test cable can carry the railway-required 1,500 volts and several hundred amperes.
No doubt, cooling adds costs to normal power transmission, but the institute says that if it can make the distance of one power line more than 1 km, it could reduce the cost by utilizing existing power transmission facilities.
The advantage of eliminating power transmission losses would definitely outweigh the additional cooling cost then, notes the institute.
According to RTRI, superconducting power transmission also has the advantage of reducing the number of substations needed to maintain voltage.
Substations are located every 3 km, and the annual maintenance cost is estimated to be $173,000 per substation.
Image and content: Kotaro Fukuoka/Nikkei Asian Review