Adapter reduces chargers’ wasted energy emissions

A power adapter designed at City University London is said to reduce the amount of energy wasted when the recharging devices are left plugged into household mains outlets.

Developed by Sanowar Khan, professor of instrumentation and sensors at the university, the patented design relies on a micro-switch, which can be embedded in any type of connector between the charger and the device. This prevents the flow of electricity when the device is not connected.

‘If you visualise your adapter, you will have a terminal that is connected to the socket, which we call primary, and the other terminal that is on the mobile end, which we call secondary,’ Khan explained. 

‘When you connect your mobile phone, the primary circuit is switched on by the very fact that you are connecting your mobile to the adapter. When you disconnect the mobile telephone, it automatically disconnects the primary.’

Khan told The Engineer that there are studies that show that 65 per cent of UK mobile phone users leave their chargers plugged in once a week.

Estimates also show that redundant adapters are responsible for six gigawatt-hours of energy – equivalent to six large power stations each working for one hour – being wasted each year. According to the Lawrence Berkeley National Laboratory in California, the amount of standby energy used globally is responsible for one per cent of carbon-dioxide emissions.


The mobile phone industry has received criticism for carbon emissions. This was one of the issues that led the industry body GSMA and 17 leading mobile operators to last year announce their commitment to implementing a cross-industry standard for a universal charger for new mobile phones.

One aim of the GSMA-led initiative is to ensure that new phone charger connections reduce standby energy consumption by 50 per cent.

The group stated that the universal charging solution will be available worldwide by 2012 and will use Micro-USB as the common universal charging interface. This is the connection found in phones such as the Blackberry Storm.

Mobile phone companies in the UK, as well as major handset manufacturers, have agreed on the new universal charger.

Khan hopes that his design idea is considered for future universal chargers and he is looking to licence the patent to a manufacturer. Beyond mobile phones, he is also targeting the connector for use with laptops and MP3 chargers.