This is worth noting given the amount of energy that goes into mobile content use. Five of the top handset makers have launched a star-rating system to compare the energy-efficiency of cellphone chargers; most wall chargers consume the greatest share of their electricity when disconnected from the phone but still plugged in. The group of five – LG, Motorola (NYSE: MOT), Nokia (NYSE: NOK), Samsung and Sony (NYSE: SNE) Ericsson (NSDQ: ERIC) – say almost two thirds of the energy used by mobile devices is wasted when nothing is being charged. The new rating system will indicate how much energy each charger uses when left plugged into the wall after charging is complete.

The ratings system, using zero to five stars, will cover all chargers currently sold by the five companies. For the ratings, each of the companies will adhere to criteria outlined at the Environmental Protection Agency and European Union. The project, which was initially presented by Nokia, also calls for a regular review of the ratings system. The group said if the three billion people who own mobile devices simply switched to a four or five-star charger it would save the same amount of energy produced by two medium-sized power plants each year. What the group failed to say, however, is why they don’t simply discontinue all the power-hungry chargers and include the best chargers available with their devices at the point of sale. Nokia, for its part, said it’s slowly phasing out the more power-hungry chargers with each new device. Release.