Here are the main providers in Brighton, and where they source their energy from:
Electric Blue Ltd - Who manage all of Brighton & Hove Council's charge points, source all their electricity from Good Energy, one of the Greenest energy suppliers there is in the UK. Good Energy are passionate about 100% renewable energy.
Charge Your Car / Polar - Operate a few charge points in the city at private car parks. Source their renewable energy from OVO Energy.