Transport for London (TfL) has signed a 15-year Power Purchase Agreement (PPA) with EDF Renewables UK, via its subsidiary Longfield Solar Energy Farm Limited, to supply solar electricity to the London Underground. The agreement marks a step towards TfL’s goal of sourcing 100% of its electricity from renewable sources by 2030.
Construction of the Longfield Solar Energy Farm in Essex is set to begin in 2026. When operational, the site will supply approximately 80 GWh of electricity annually to TfL—enough to power more than 29,000 homes. This represents around 20% of the solar farm’s total output. Over the duration of the contract, TfL estimates it will receive 1.2 TWh of clean energy, equivalent to running the Tube network for an entire year, and expects to reduce carbon emissions by over 28,000 tonnes.
The solar facility will also feed up to 400 GWh of electricity per year into the National Grid, contributing to the UK’s wider decarbonisation efforts. EDF Renewables UK secured planning permission for the 400-hectare site in 2023. The project includes plans to restore biodiversity through tree planting, hedgerows, and natural regeneration, with an anticipated biodiversity net gain of 87.1%, significantly exceeding the 10% legal minimum.
As one of the UK’s largest electricity consumers, TfL currently uses around 1.6 TWh of electricity per year. This new PPA is part of a broader energy purchasing strategy, which aims to source up to 70% of its electricity through similar agreements. TfL is also inviting tenders to build directly connected solar farms that could supply up to 64 MW of electricity for the network.
The announcement coincided with the launch of a new climate finance taskforce to help unlock £75 billion of private investment in green projects across London.
Sadiq Khan, The Mayor of London, said: "London is already a world leader when it comes to addressing the climate crisis, so it's only right that we continue blazing this trail when it comes to our transport system. This new agreement will enable us to power our transport network with clean, green, renewable energy and reduce TfL's carbon emissions as we continue building a greener and better London for everyone."