 High-voltage direct current (HVDC) lines have the capability of transmitting similar wattages, for example a 5 gigawatt HVDC system is being constructed along the southern provinces of China without the use of superconducting cables.In the United States, a Continental SuperGrid 4,000 kilometers long might carry 40,000 to 80,000 MW in a tunnel shared with long distance high speed maglev trains, which at low pressure could allow cross continental journeys of one hour.The liquid hydrogen pipeline would both store and deliver hydrogen.