The process of PHAs production from plant oils can be made
more efficient by utilizing all parts of oilseed plants. Currently,
mainly the seeds are used, whereas the rest of the plant is discarded.
Harvesting the plants produces large amounts of waste
biomass, and then processing the plants for oil production usually
creates oil cake or oil meal as waste by-products. These wastes
could be used as substrates for anaerobic digestion for the production
of biogas. The biogas could be used to heat the bioreactors
where the PHAs are produced. This integration of PHAs production
with biogas production is an attractive integrated technology
concept (Fig. 5).