The batteries that power electric cars, smartphones and other devices are often made of lithium, which poses a problem since lithium is a toxic material with limited supply and is difficult to dispose.

A newly developed system for generating electricity, however, does not require the use of metals and toxic materials, which could potentially pave way for more environmentally friendly batteries in the future.  

Researchers from MIT have come up with this new source of power that uses wire made from tiny carbon cylinders called carbon nanotubes to produce electric current.

The system produces power when the wire is progressively heated from end to end. This is done by coating the wire with combustible material and then lighting one end so it burns like a fuse.

The combustible material that the researchers used is sucrose, more commonly known as the ordinary table sugar, which is benign and non-toxic.  The researchers however believed that other combustion materials can produce higher efficiencies.

What makes the carbon nanotube-based power system different from other technologies is that it only works on heat so once better heat sources are developed; they can be used in the system to improve performance.  

Michael Strano, from MIT, and colleagues, who worked on the system, already showed that the wires are capable of powering simple devices such as LED lights albeit it will likely take time before the technology can compete with the widely used lithium-based batteries.

The power source may be scaled down for use in tiny wearables that are already in the market but researchers think it can also be scaled up for use in deep-space probes. The system can remain dormant for a long time as the probe travels through space and only gets tapped for power by applying heat.

"I believe that we are still far from the upper limit that the thermopower wave devices can potentially reach," said Kourosh Kalantar-Zadeh, from the RMIT University in Australia, who was not part of the research. "However, this step makes the technology more attractive for real applications."

Strano and colleagues described their work in a paper published in the journal Energy & Environmental Science.

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