The move will require the renegotiation of a £1.5bn, 30-year PFI deal.
Power for the Tube is presently supplied by a Seeboard, a consortium made up of EDF Energy, Balfour Beatty and ABB. If it is able to meet the extra demand, the value of the contract could rise to £2bn.
A Seeboard spokesperson said that the group was hopeful that it could supply the required electricity. He added that a design team was about to start work on ways to fulfil the request.
The additional energy is needed because Tube managers do not think the present agreement will be sufficient to renew the system and power additional rolling stock.
The decision to review the Tube's energy requirements comes after a power failure in August that led to the closure of the capital's transport system for several hours. An LU spokesperson emphasised, however, that there was no link between that incident and the decision to upgrade power supplies.
We have to deliver this before the new trains come on line in 2009
Tube chief Tim O’Toole
Tim O'Toole, the managing director of LU, said: "We have to amend the deal to deliver additional power for the PPP. It is a big assignment. This is not a minor amendment."
O'Toole said LU was under pressure to complete the deal by next year in order to have the extra power in place before new trains come on line in 2009.
O'Toole said LU was working with the Tube consortiums Metronet and Tube Lines to assess their particular energy needs.
The decision by the government to provide energy for underground through a PFI contract was sharply criticised after the summer power cut revealed that there was no back-up supply. The energy supply was linked to the national grid, with any extra coming from a power station in Greenwich, south-east London.
O'Toole said another PFI deal signed by LU for a communications system called Connect had been delayed by three years.