Two Step In Situ Steam Gasification Following Pyrolysis of Food Waste for Enhancing H2 Production

Abstract

Rapid rise in generation of food waste has led to increase in concern about food waste management. Since current methods such as landfilling and incineration result in the emission of greenhouse gases, there is a need to develop new technologies that can help manage food waste. Biochemical and thermochemical conversion of food waste into biofuels offers a promising alternative. Although biochemical conversion offers promising results, it is a slow process and requires specific microorganisms to produce biofuels. On the other hand, thermochemical conversion processes can be used to produce syngas, methane, and hydrogen. This study focuses on the thermochemical conversion of food waste by utilizing a conventional and novel in-situ two-step steam gasification process. newlineThe first study presented in Chapter 5 showed the suitability of food waste as a feedstock for thermochemical processes like fast pyrolysis and steam gasification. The syngas yield obtained from these processes (pyrolysis and steam gasification of food waste) was close to the syngas obtained from typical ligno-cellulosic biomass. Thereafter, as presented in Chapter 6, attempts were made to increase the syngas yield by separating pyrolysis and steam gasification, however, both were carried out at the same temperature. This process was called as in-situ two-step process (ITP) of steam gasification. The syngas yield from this novel process of ITP increased to 1.45 Nm3/Kg, an increase by 11%. However, the average hydrogen fraction did not change much. newlineThe next chapter, chapter 7, presents the effect of change of temperature on syngas characteristics from ITP of steam gasification of food waste. Characteristics of syngas (syngas yield, composition, H2 yield, and high heating value (HHV)) from the proposed approach was first compared with that from a conventional overlapping process (COP) of steam gasification process at the same temperature of 700 oC and then with that from ITP at a higher temperature of 850 oC. Syngas yield from ITP at 700 oC (0.91 m3/Kg)