An Environmental Analytical Model to Assess the Decarbonization Potential of Municipal Solid Waste-Based Hydrogen Production Routes

The hydrogen production route currently identified as most promising from an environmental point of view is water electrolysis. This process does not produce direct emissions and is potentially zero-emission if fuelled by electricity from renewable sources. An electrolyser, however, has a high energy consumption (on average of 5 kWh/Nm3H2). This is a barrier to the implementation of electrolysis on an industrial scale. In this regard, the so-called Waste-to-Hydrogen routes represent a valuable alternative. They consist of treating waste to obtain hydrogen as a primary product. This paper aims to evaluate the decarbonisation potential of two MSW-based hydrogen production routes: a WtE plant coupled with an electrolyser (WtE+El) and a gasification plant with a syngas treatment unit to produce H2 (WtH2). Consistent with this end, the potentials of two hydrogen production routes were compared with the two most discussed hydrogen production routes. The first is the SMR process, considered the most widely used alternative for hydrogen production. The second is water electrolysis, considered the most promising from an environmental point of view. To this concern, an environmental analytical model was developed to evaluate each alternative based on its associated emissions. The results obtained from the application of the model showed that the best hydrogen production route from an environmental point of view is the WtH2 route. It shows a total emission amount of 1.18 kgCO2eq/Nm3H2, which is 8.5% lower than the SMR route, 31% lower than the El route and 63.2% lower than the WtE+El route.