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Could Small Springs Beat Batteries?

MIT scientists have found that carbon nanotubes could be formed into tiny springs capable of storing as much energy, pound for pound, as the best lithium-ion batteries - potentially more durably and reliably.

Carol Livermore, associate professor of Mechanical Engineering, found that carbon nanotube springs can potentially store more than a thousand times more energy for their weight than steel springs.

Livermore explains that for some applications, springs can have advantages over other ways of storing energy. Unlike batteries, for example, springs can deliver the stored energy effectively either in a rapid, intense burst, or slowly and steadily over a long period. Also, unlike batteries, stored energy in springs normally doesn't slowly leak away over time.

For that reason, the springs could be ideal for use in emergency backup systems. With batteries, such devices need to be tested frequently to make sure they still have full power, and replaced or recharged when the batteries run down.

Livermore says that the springs made from these minuscule tubes might find their first uses in large devices rather than in micro-electromechanical devices. The best uses of such springs may be in cases where the energy is stored mechanically and then used to drive a mechanical load, rather than converting it to electricity first.