Waste Gasification for Hydrogen Production
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University College London (UCL)
Abstract
The vision for hydrogen being at the forefront of the energy transition is already in existence, due to its
high energy density and its zero greenhouse gas emissions during use. Current production methods
include steam-methane reforming and coal gasification, which lead to high CO2 emissions that will
amplify climate change with increasing demand. Opposite to this is waste gasification, which provides
a sustainable gateway for clean hydrogen production as waste contains biogenic carbon and can attain
negative carbon emissions when coupled with carbon capture and sequestration (CCS). This study
concentrates on the development of a novel approach to predict the pyrolysis yields of diverse waste
based on its components of cellulose, hemicellulose, lignin, polyethylene and polypropylene. The work
demonstrates that the flexibility and predictive capability of an air-steam bubbling fluidised bed (BFB)
gasification model for a wide array of waste types is improved. The model was rigorously validated
against pilot plant data through comparison of the outlet syngas composition, the tar content, the heating
value and the temperature profile across the fluidised bed gasifier at a range of conditions. The effects
of the feedstock type, equivalence ratio (ER) and the steam-to-waste ratio (STWR) are investigated to
determine the optimal conditions for achieving a high H2 yield, while maintaining medium heating
values. It was found that a H2/CO ratio of 2.37 is achieved with an ER of 0.30 and a STWR of 1.2 using
sugarcane bagasse.
Description
The vision for hydrogen being at the forefront of the energy transition is already in existence, due to its
high energy density and its zero greenhouse gas emissions during use. Current production methods
include steam-methane reforming and coal gasification, which lead to high CO2 emissions that will
amplify climate change with increasing demand. Opposite to this is waste gasification, which provides
a sustainable gateway for clean hydrogen production as waste contains biogenic carbon and can attain
negative carbon emissions when coupled with carbon capture and sequestration (CCS). This study
concentrates on the development of a novel approach to predict the pyrolysis yields of diverse waste
based on its components of cellulose, hemicellulose, lignin, polyethylene and polypropylene. The work
demonstrates that the flexibility and predictive capability of an air-steam bubbling fluidised bed (BFB)
gasification model for a wide array of waste types is improved. The model was rigorously validated
against pilot plant data through comparison of the outlet syngas composition, the tar content, the heating
value and the temperature profile across the fluidised bed gasifier at a range of conditions. The effects
of the feedstock type, equivalence ratio (ER) and the steam-to-waste ratio (STWR) are investigated to
determine the optimal conditions for achieving a high H2 yield, while maintaining medium heating
values. It was found that a H2/CO ratio of 2.37 is achieved with an ER of 0.30 and a STWR of 1.2 using
sugarcane bagasse.
Keywords
Hydrogen, Carbon capture and sequestration, Sustainable energy, Gasification, Fluidised bed, Plastic waste, Climate change, Clean energy, Biomass, Energy transition, BECCS, Green
Citation
T. Lahig, 'Waste Gasification for Hydrogen Production', Masters of Science, Department of Chemical Engineering, University College London, London, United Kingdom, 2023.