But Schindall also says the concept has merit. “I’m cautiously intrigued, because he does have some legitimate arguments for the fact that at these quantum dimensions, the energy storage effect is at least predicted to go up considerably,” Schindall says. “The first challenge is: are his assumptions correct, or are there some other phenomena that haven’t been looked at that get in the way?”
In some ways, the concept represents a variation on existing micro- and nanoelectronic devices. “If you look at it from a digital electronics perspective–it’s just a flash drive,” says Hubler. “If you look at it from an electrical engineering perspective, you would say these are miniaturized vacuum tubes like in plasma TVs. If you talk to a physicist, this is a network of capacitors.”
The digital part of the concept derives from the fact that each nanovacuum tube would be individually addressable. Because of this, the devices could perhaps be used to store data, too.
Other methods exist for boosting the performance of capacitors. Advanced versions, called ultracapacitors, can store significant energy and operate more quickly by increasing the surface area of their electrodes and using an electrolyte. Schindall’s group has increased the charge and discharge rates and storage capacity of traditional ultracapacitors by using carbon nanotubes instead of activated carbon on the electrode’s surface. In essence, this increases the surface area of the electrode.
The advantages to Schindall’s design–increased power output and energy density–could be crucial for applications like soaking up huge pulses of energy rapidly from a field of wind turbines or solar arrays, for example. Plus, his team has actually built a benchtop device. The downside is that the energy density of a given mass of material would still be somewhat lower than that of lithium-ion batteries.
While Hubler hasn’t yet built anything, he notes that, in 2005, a group of Korean researchers showed that nanoscale capacitors could be fabricated. Hubler’s device would still need billions or even trillions of such devices, however.
“I complete agree we desperately need new ways of storing electric energy,” says Schindall. “Though it may be in competition with what I’m doing, I wish him the greatest of success and hope it works.”