Other avenues, such as caloric restriction, an extreme form of dieting, have also gained fresh attention amid an unprecedented wave of research — and investment dollars — into the business of ageing.

So in a world where investment dollars are commoditised for the best ideas and teams, how do you persuade the star entrepreneurs to allow you to invest?

All are closed-end, meaning the number of investors and amount of investment dollars are capped.

Solar accounted for almost 40% of total clean technology investment dollars in 2008, followed by biofuels at 11%.