Vanadium: The metal that may soon be powering your neighbourhood
Hawaii has a problem, one that the whole world is likely to face in the next 10 years. And the solution could be a metal that you've probably never heard of - vanadium.
Hawaii's problem is too much sunshine - or rather, too much solar power feeding into its electricity grid.
Generating electricity in the remote US state has always been painful. With no fossil fuel deposits of its own, it has to get oil and coal shipped half-way across the Pacific.
That makes electricity in Hawaii very, very expensive - more than three times the US average - and it is the reason why 10% and counting of the islands' residents have decided to stick solar panels on their roof.
The problem is that all this new sun-powered electricity is coming at the wrong place and at the wrong time of day.
Hawaii's electricity monopoly, Heco, fears parts of the grid could become dangerously swamped by a glut of mid-day power, and so last year it began refusing to hook up the newly-purchased panels of residents in some areas.
And it isn't just Hawaii.
"California's got a major problem," says Bill Radvak, the Canadian head of American Vanadium, America's only vanadium mining company.
"The amount of solar that's coming on-stream is just truly remarkable, but it all hits the system between noon and 4pm."
That does not marry well with peak demand for electricity, which generally comes in the late afternoon and evening, when everyone travels home, turns on the lights, heating or air conditioning, boils the kettle, bungs dinner in the microwave, and so on.
What the Golden State needs is some way of storing the energy for a few hours every afternoon until it is needed.
And Radvak thinks he holds the solution - an electrochemical solution that exploits the special properties of vanadium.