Poly(3-hydroxyalkanoates) (PHA) have the to become a biodegradable alternative for conventional plastics. In order to produce PHA at competitive costs in comparison with commonly used plastics, efficient PHA production systems will have to be developed. Poly(3-hydroxybutyrate) fermentations are well developed and in actual use on an industrial scale : medium-chain-length PHA (mcl-PHA) production is less well described, although the vast majority of all PHA known today are mcl-PHA. This paper compares and describes mcl-PHA production systems with respect to the volumetric productivity, the cellular PHA content and the polymer yield on carbon substrates. Nitrogen was shown to be the most effective limitation to trigger PHA formation in P. oleovorans after different nutrient limitations had been compared. By using an economic model for the calculation of PHA production costs, we show that it should be possible to produce octane-based mcl-PHA on a large scale (more than 1000 tonnes/year) at costs below U.S. $ 10 kg(-1).