“Under the project, sponsored by Royal Dutch Shell, around 200 energy-capturing tiles developed by British startup Pavegen were installed the width and breadth of the field and covered by a layer of AstroTurf. Working in conjunction with solar panels also installed around the field, the player-powered tiles feed electricity to a system of floodlights overhead.” (source)
Below are videos about this initiative.
Note: As of 1 Aug 2024, the videos were no longer available.