is one of the UK's largest uses of electricity, last year consuming 2.3 TWh of power to run its national networks, data centres, and offices - equivalent to 0.76 per cent of all the electricity used in the UK.
The company said that switching from standard power to renewables on this scale would result in carbon emission savings equivalent to one million tons.
The move was welcomed by Energy and Climate Change Secretary Ed Davey
, who urged other companies to follow BT's lead and commit to sourcing renewable power.
"I hope many other corporates will follow the lead of BT and others, in taking their electricity from renewable and low carbon sources."
A spokesman for the company said that it hoped that increasing corporate demand for renewable power will send a signal to energy firms and encourage them to develop more clean energy capacity.
, BT's director of energy and carbon, said "BT strives to help society live within the constraints of our planet's resources through our products and services," he said. "This is an example of BT's commitment to be a responsible and sustainable business leader."
chief executive of RWE npower, who said the deal provided further evidence
"renewables are important to the UK and to British business".
Well done BT - thats worthy of celebration