Feynman's famous 1959 proclamation “There's plenty of room at the bottom” largely referred to the untapped storage ability for information at the nanoscale.
However, recently published results by Banerjee and co-workers [Banerjee, et al., Nat. Nanotechnol. (2009), doi: 10.1038/nnano.2009.37] show that this credo applies to energy storage as well.
The team has created arrays of nano-scale capacitors with an unprecedented 100 μF/cm2 capacitance, more than 40 times larger than the equivalent capacitance for a planar configuration. The devices were made by the successive application by atomic layer deposition of metal (TiN) and insulator (Al2O3), onto a nanoporous template of anodic aluminum oxide to create a densely packed array of these capacitors. This nanoscale design allows for the desired combination of the typically high power density provided by capacitors (106 W/kg) along with the high energy density available by tapping available surface area and volume at the nanoscale (0.7 W*h/kg). In fact, these devices provide 10 times the energy storage density of commercially available devices. According to Rubloff, one of the authors, “While electrostatic capacitors, which hold energy simply as electrical charge on the surface of opposing sheets of metal, are well known to provide high power, their energy density has been low, and accordingly they have not been considered as part of the storage solutions requiring significant energy. Now we have shown the potential of electrostatic nanocapacitors to compete with conventional electrochemical capacitors, bringing a new player onto the field of storage solutions.”
These new nanocapacitor devices may soon be coming to the market. The technology is being developed for mass production as a panel similar in shape to solar panels. These panels could be then integrated with energy generation technologies such as solar cells or wind, to capture and store the time-varying, unpredictable energy generated. The unique combination of high energy, high power, and quick recharge times, coupled with the low cost manufacturability, shows great promise for this technology in next-generation energy storage.