DISCARDED BIOMASS AND AGRICULTURE ROLE PERSPECTIVES IN THE HYDROGEN SECTOR

摘要

Hydrogen is more and more viewed as one of the most pure and viable energy vectors for the future. However there are a lot of problems connected to its production: hydrogen is not a primary energy source but a product that is obtained by electrolysis or mainly by steam reforming. As an example of critical aspects, taking into account an efficiency for the electrolysis process of 70% and for fuel cells of 50%, starting from 6.3 kWhel it is possible to obtain through hydrogen only 2.2 kWhel (by fuel cells). Thus this option is not very efficient. In spite of that, hydrogen can be advantageous in particular conditions, thanks to its high energy content. For this reason, solutions that include the discarded biomasses in the hydrogen scenarios are more and more suggested by the researchers. In this paper some aspects about these solutions are discussed referred to three discarded biomasses: sewage sludge, organic fraction of municipal solid waste, exhausted grape marc. Energy considerations are presented in order to understand if an option is ready for the commercial scale. Some considerations on a reference region where biomasses are generated allow to understand the energy potential. Concerning sludge, the analysis pointed out that most of the present international research is aimed to decrease the amount of sludge (referred to dry matter). As a consequence the energy exploitation of sludge seems to be more and more critical. More in general, if the target is the implementation of a sustainable strategy based on hydrogen, a viable solution can the coupling of electricity generation from biomass (a renewable source) and electrolysis for hydrogen generation. Considering the high cost of hydrogen, its adoption should be made in particular cases where the health benefits are significant.