The fuel cell which part-powers Al Gore's London HQ
5 December 2013 Last updated at 00:01 GMT
A fuel cell has been fitted in the basement of a new development off Regent Street in London.
Developers the Crown Estate say the cell is the first of its type to be used in the UK, and will provide some 20% of power to a mixed-use development comprising four distinct buildings.
Tenants include former US Vice President Al Gore's sustainable investment management company Generation.
Video journalist: Neil Bowdler