Refusing plans for an electricity link between Denmark and the UK would compromise the latter's ability to source energy, a planning inquiry was told.
The Viking Link is a proposed 473-mile (761km) electricity cable between Bicker Fen, near Boston, and Revsing, in southern Jutland.
It includes about 40 miles (64km) of underground cable running through four Lincolnshire council districts.
Opponents question its impact.
The planning inquiry, being held in Manby, Lincolnshire, heard the Viking Link was vital to the UK's energy security.
Michael Humphries QC, speaking on behalf of National Grid Viking Link, said: "To refuse planning permission would be to compromise the UK's ability to meet the urgent need for new infrastructure of this type."
As part of the scheme, planning applications were submitted to councils in East Lindsey, North Kesteven, Boston and South Holland.
East Lindsey was the only council to refuse permission, fearing the impact upon farming and the landscape.
It has now dropped its objections after accepting the impact of the work would be temporary, according to the Local Democracy Reporting Service.
However, others questioned why alternative routes had not been chosen as the preferred route goes through an Area of Outstanding Natural Beauty.
Concerns were also raised about drainage and plans by a developer to build holiday homes along the route.
The project, which is said would reduce prices and provide low carbon energy for one million households, is a partnership between the Danish electricity transmission company Energinet.dk, and the UK's National Grid.
If approved, underground cables would carry electricity from Sutton-on-Sea to a new converter station near Donington, and on to the existing National Grid substation at Bicker Fen.
The inquiry is expected to last until Friday.