Zero-waste approach for combined energy and fertilizer production: The case of Ravenna, Italy

There is a need to find a solution to solve the problem of increasing agricultural practices which can lower the pressure on soil. Application of compost or biochar to the soil is proved to be a suitable solution to counteract this problem. Mixed application of these two products is even more sustainable environmental solution due to its effectiveness in the long-term carbon preservation. The biochar can be produced through gasification of municipal waste as a method for renewable energy production. This makes a new market for the unused biomass which is currently incinerated or landfilled. This paper summarizes the technical and economic aspect of system innovation toward utilizing organic and green waste for composting and energy production via gasification and application of the products (compost and biochar) for soil amendment, considering the case of Ravenna city in Italy. The municipal statistic data on waste management were used for this purpose. Gasification experiment of green waste for electricity production was performed in an open-top gasifier. The obtained results showed that the available waste in Ravenna could be used for production of large portion of energy consumption and at the same time provide biochar and compost mixture to be used in 700 hectare/y of the agricultural land in Ravenna. Moreover, the available methods and conditions in literature for mixing of biochar and compost were reviewed. The related European directives were also discussed.