In the home, energy savings from efficient lighting and appliances have been completely wiped out by increased use of computers and gadgets, and by 2025 a 'tsunami of data' is expected to consume a fifth of global electricity.
But this new device would immediately reduce peak power consumption in data centres by a fifth.
It would also allow, for example, computers which do not need to boot up and could instantaneously and imperceptibly go into an energy-saving sleep mode - even between key stokes.
The device is the realisation of the search for a "Universal Memory" which has preoccupied scientists and engineers for decades.
Physics Professor Manus Hayne of Lancaster University said: "Universal Memory, which has robustly stored data that is easily changed, is widely considered to be unfeasible, or even impossible, but this device demonstrates its contradictory properties."
The inventors of the device used quantum mechanics to solve the dilemma of choosing between stable, long-term data storage and low-energy writing and erasing.