Integral energy valorization of municipal solid waste reject fraction to biofuels

Nowadays, the waste generation increases more and more, especially of the municipal solid waste. The municipal solid waste reject fraction may be valorized from an energy point of view. With this aim, a conceptual design of a process was developed by considering material and energy integration, which mainly consists of three sub-processes: fast pyrolysis of municipal solid waste to produce bio-oil, supercritical water reforming of the bio-oil aqueous phase to produce hydrogen to be used in the third section, which is the upgrading of the organic phase of the bio-oil by hydrodeoxygenation. The overall system was simulated using Aspen Plus software to achieve the highest process performance and the lowest utilities requirement. The former was assessed by the biofuel production (liquefied fuel gas, gasoline and diesel) and the net electrical power. In addition, the potential economic profitability of the plant was performed by specifying the main process units. Thus, for a feeding of 50 t/h of municipal solid waste reject fraction, a generation of a net electric power equal to 10.65 MWe and a production of 5.2 t/h biofuels (21.1% of the carbon present in the municipal solid waste) may be achieved, thus obtaining a very low gate fee (16.7 (sic)/t) using the same industrial selling prices that those of fossil fuels and electricity in a full plant. Therefore, the process seems to be technically and economically feasible.