Siemens and Prysmian have been awarded a contract for the construction of the first sub-sea electricity link between Scotland and England.
The £1 billion contract for the 261 mile line, which will run from Hunterston in Ayrshire to a landing point on the Wirral peninsula, was awarded by National Grid and ScottishPower.
The new link will enable large volumes of renewable wind and other energy generation to be transferred from Scotland to areas of higher demand in England. The firms said it will be the longest 2,200MW capacity high voltage direct current (HVDC) cable in the world.
National Grid executive director Nick Winser said: "This link will have a vital role to play in meeting both the country's energy needs and helping to address the problem of climate change.
"We are investing in an innovative solution using the most advanced technology. As a result, the benefits for consumers and electricity generators in being able to transport power in the most efficient way will be felt for years to come."
The energy firms said that it will also be the first sub-sea link ever using a direct current voltage level of 600 kilovolts (kV), which will increase the link's capacity and lead to lower transmission losses. It is planned to be fully operational by 2016.
Ignacio Galan, chairman of ScottishPower, said: "The HVDC link is a major project in the context of a vital upgrading of the UK electricity grid over the coming years, with the electricity grid between Scotland and England already running close to maximum capacity.
"The additional capacity from this link will provide a significant boost to renewable energy projects that we are developing in Scotland in order to bring clean energy to consumers throughout the country and at the same time help meet carbon reduction targets.
"We are fully committed to playing our part in the UK Government's planned infrastructure development programme and expect to invest a total of £2.6 billion between 2013-2021 on upgrading our transmission network in the UK.
"Overall, we are projecting investments totalling £12 billion in the UK over the course of this decade, including major offshore wind projects around the country."
Work began on the project in 2009.