Valorisation of grass, pasture and plant wastes using the biorefinery concept
The potential of these wastes is currently not exploited as the usual actions are composting, direct use in animal feed, conversion to pellets for energy production or biogas production by fermentation.
Using the biorefinery concept, protein-rich compounds for pig feed, sugar and protein-rich compounds for cattle feed, fibres for cardboard manufacturing, as well as electricity and heat can be produced.
The technology consists of a first mechanical separation step where the input is converted into a pressed fibre cake and a juice rich in protein and minerals. The juice is then heated to produce a protein coagulate, useful as feed in the pig sector. As for the cake, it is low in protein but suitable for livestock feeding needs. The cellulose fibres it contains can be transported for the manufacture of cardboard. Finally, the residual fractions from the process are used to produce biogas. The decentralised approach makes it possible to avoid the transport of wet green leaf and grass waste, thus reducing emissions. Moreover, the substitution of soya feed with local feed allows for a more sustainable production. This technology has been developed by Wageningen University and is marketed by GRASSA BV. On the other hand, other approaches to the biorefinery concept could include the production of acids (lactic acid and amino acids) or lignin, and different scenarios can be developed depending on the complexity of the valorisation process.
Market deployment considerations