Another company looking to harness the potential of gravity is Advanced Rail Energy Storage (ARES), based in Santa Monica, California.

ECONOMIST: Energy storage

David Vieau -- right over here -- is President and CEO of A123 Systems, a company that produces advanced batteries for energy storage and next-generation vehicles.

WHITEHOUSE: President Obama Makes Statement on Economy and Oil Spill

China, America, Europe and the rest of the world must rapidly accelerate the pace of improvement in a whole suite of clean energy technologies, from nuclear and solar alike to plug-in hybrid vehicles, energy storage, and advanced biofuels.

FORBES: Connect

In his speech, Mr Osborne set out seven further areas where the government thinks Britain is a world leader and can and must go further: computing, synthetic biology, regenerative medicine, agricultural science, energy storage, robotics and advanced materials including nanotechnology.

BBC: Space spending to be increased by ?60m a year

However, he warned against focussing disproportionately on the eight areas of excellence outlined by the Chancellor in November ("big data" computing, synthetic biology, regenerative medicine, agricultural science, energy storage, space, robotics and advanced materials including nanotechnology).

BBC: Autumn Statement: Science gets ?600m injection

In addition to nukes, OR-SAGE also examines advanced coal with carbon capture and storage, solar and compressed air energy power plants.

FORBES: Plotting The Next-Generation U.S. Power Grid

This type of grid-level storage is a priority for the Department of Energy's Advanced Research Projects Agency-Energy, or ARPA-E, program.

FORBES: Out Of The Labs

It was to no avail: the participants failed to agree on a global mechanism to put a price on emissions, making it harder for energy firms to justify big investments in unproven green technologies, such as advanced biofuels or carbon capture and storage.

ECONOMIST: Business comes to terms with a disappointing outcome