From Steorn's Website:
Orbo is based upon the principle of time variant magneto-mechanical interactions. The core output from our Orbo technology is mechanical. This mechanical energy can be converted into electrical energy using standard generator technology either by integrating such technology directly with Orbo or by connecting the mechanical output from Orbo to the generation technology. The efficiency of such mechanical/electrical conversions is highly dependent on the components used and is also a function of size.
Orbo technology is subject to continuous development. This development is focused on improving the manufacturability of the technology, production costs and power density. Orbo was initially developed as using stop-start mechanisms (with a power density of 0.5 Watts per cm3), Steorn is currently finalizing the development of constant motion systems and a significant improvement in power density is anticipated.
Not exactly what I expected, but hey, this is their show, not mine.