The paper industry has historically managed resources in a linear logic: cellulose enters the process, paper comes out, and, with that, tons and tons of waste are disposed of. It can be estimated that up to 16 million tons of sludge are produced globally each year (Turner et al, 2022). What if that waste could instead get a second life by transforming into useful green energy? The Sludge-To-Energy project, or “S2E”, tackles this challenge by providing an innovative system able to convert organic matter into electrical energy. The sponsor and client of the project is Fedrigoni S.p.A., leader in the paper production industry, that wants to be pioneer of innovative waste-to-energy solutions.
The objective of the research is to understand if the organic sludge can be recycled in order to extract energy from it in a sustainable way. For the purpose, experts were interviewed, and different laboratory analyses were conducted. This approach let the team achieve noteworthy results:
- The paper sludge proved to hold a great energetic potential. In particular, the Fabriano paper plant will be home of the first pilot system, which is estimated to produce over 200 kW of continuous electrical power.
- The project was found to be economically sustainable, with an estimated payback time of 10 years, over a plant lifetime of 20 years. This is due to the revenue streams coming from the sale of the produced green energy to the grid, together with the avoided costs deriving from a reduction in the amount of waste that would be disposed of in an ordinary way.
- From a socio-environmental point of view the project proved to be impactful as well, encouraging the creation of new jobs and increasing the renewable energy quota available within the national grid.
These results achieve even greater importance if combined with the originality of the project, which is twofold: to the best of our knowledge, (i) no SOFC application for paper mills’s sludge has ever been conceived, and (ii) the S2E project would become the largest industrial biogas-powered SOFC plant, at international level.
Principal Academic Tutors
Massimo Santarelli, Energy Department (DENERG), Politecnico di Torino
Stefano Campanari, Energy Department, Politecnico di Milano
Marco Moffa, Transformation Director BU Paper, Fedrigoni S.p.A.
Marco Pagliaro, Energy Manager, Fedrigoni S.p.A.
Giuseppe Speri, Operational Excellence Manager, Fedrigoni S.p.A.
Francesco Enni, Energy Engineering, Politecnico di Milano
Matteo Calò, Mechanical Engineering, Politecnico di Torino
Matteo Raviola, Mathematical Engineering, Politecnico di Torino
Nidhin T. Madhu, Materials and Nanotechnology Engineering, Politecnico di Milano
Rebecca del Vecchio, Building Engineering and Architecture, Politecnico di Milano
Sandro Zarcone, Management Engineering, Politecnico di Milano