From Wikipedia – an article on the technology already in use today in Europe – read article
The HVDC Cross-Channel (French: Interconnexion France Angleterre IFA 2000) is the 73-kilometre-long (45 mi) bi-directional high-voltage direct current (HVDC) interconnector that has operated since 1986 under the English Channel between the continental European grid at Bonningues-lès-Calais and the British electricity grid at Sellindge…read more