First, we need to make an important distinction between Energy and Power. We’ve got lots of Energy. We are getting short on Power.
Roughly speaking, if we could capture 100% of one day of sunlight energy, store it and distribute it as electric power, this would cover the entire needs of today’s world for a full year.
On the other hand, Bill Gates on GatesNotes on Energy states that “All the batteries on Earth can store 10 minutes of the world’s electric needs.” We are very short on storage.
We’ve got enough geothermal energy in Hawaii to make us self sufficient for centuries including the production of fuels for transportation.
Two big problems are: (1) We do not have sufficient infrastructure to take Energy and make Power, and (2) once we make power, we have no means to store it for later use. The second problem makes wind, solar and other intermittent power generation methods tertiary in terms of power production.
Smart grid distribution with connected electric car batteries, capacitors and intelligent management make the incorporation of renewable intermittent power more possible, but the existing capability in terms of storage and management is limited.
Unfortunately modern high capacity batteries in hybrid and plug-in vehicles require “exotic” materials in their composition. These make them very expensive and the potential for large price reductions and very high production numbers is limited.
A fairly recent development is large liquid batteries: “MIT team makes progress toward goal of inexpensive grid-scale batteries that could help make intermittent renewable energy sources viable.” The resultant spinoff company, Liquid Metal Battery Corp. has benefited from funding from the Gates Foundation.
These batteries depend on molten metal at temperatures higher than 500 C (930 F), so I was a little sceptical that large amounts of energy would be wasted in keeping the metals molten. However the authors have accounted for this in their journal publication*: “At some larger scale, the action of electric current flowing through the electrolyte could generate enough Joule heat to keep the components molten, thereby obviating the need for external heaters, as is the case with electrolytic cells producing aluminum on a commercial scale”
(*) Magnesium−Antimony Liquid Metal Battery for Stationary, Energy Storage, David J. Bradwell, Hojong Kim, Aislinn H. C. Sirk, and Donald R. Sadoway, J.Am.Chem.Soc. 2012, 134, 1895−1897.