With the BBC anxious to cut costs and reduce its CO2 emissions, a long-term project has been set up between the BBC and Arqiva (the transmission providers) to improve energy efficiency of the broadcast radio transmitters. AM (on LF and MF), FM and DAB are all within scope of the project. Work on the MF transmitters (Radio 5 and National) has already reduced the electricity bill from 12.7 to 10.6 GWh per annum.
Read more about this project here.