I must admit, my reaction to yesterday's news was "Oh good! Now if only they can actually mass-produce it cheaply enough..."

Producing useful energy from a potentially useful source will indeed involve some loss in the conversion. (Second Law of Thermo, folks.) The trick often is to use a more acceptable energy source when doing the conversion... so (for example) making fuel alcohol from biomass using solar or wind power may be less energy-efficient (strictly speaking) than refining crude oil by current processes, but it's still better for us in the long run.