Title : Transforming waste plastic into renewable hydrogen: a review of progress, challenges and future directions through pyrolysis, distillation and hydrotreatment process
Abstract:
The collective problem of waste disposal is now a landfill crisis exasperated by current limitations imposed on exporting waste, for which organic waste is a major driver, combined with high gas prices (heating costs) and electricity. This project offers flexible, modular, and scalable integrated small-scale bioenergy solutions that could be utilised with many waste feedstocks at the generation source with value-added by-products such as biochar, hydrogen, and heat utilised in the vicinity, minimising transport costs. This project is highly synergistic with the core waste-to-energy solution because it creates additional value-adding turnouts. Large waste-to-energy projects struggle to gain community support and government approval. It is also difficult logistically to source reliable waste streams of sufficient volume, with the result that large projects can lock waste providers into long-term ‘waste production. The heat engine transforms the economics of waste into energy because it generates up to three times the electricity from the same heat source. For the first time, small-scale waste to energy is a reasonable commercial possibility. Plastic waste can be a significant source of energy for human needs. The range of wastes can be considered feedstocks used to produce renewable energy. Mixed plastic waste constitutes a large portion of landfill solid waste, whose management is a big problem and needs attention. Waste plastics can be converted to produce crude plastic oil, but their qualities are critical to industry refining processes for automobile use. Thermo-chemical conversion of plastic waste for energy recovery can be a viable option. Thermo-chemical conversion using a Pyrolysis reactor can be used to thermally decompose plastic waste to produce crude plastic oil, which then can be processed through vacuum distillation and hydrotreatment to produce automobile diesel (like commercial diesel fuel). This project also will propose using the pyrolysis process to produce syngas and bio-oil that will eventually be converted and separated to produce hydrogen. A portion of the produced hydrogen will be used to produce NH3, and the remainder will be consumed to produce green power utilising a fuel cell. The biochar will be mixed with nitrogen, stimulating the crops through slow nitrogen-release fertiliser. The activities associated with this proposal will offer an option to develop renewable NH3 using less energy-intensive low-pressure technologies. They will eventually assist in minimising the farm sector's greenhouse gas production. The outcome of the proposed project will be valuable in terms of managing landfill waste more efficiently and effectively, producing low-cost and low-emission energy and renewable NH3, and enhancing the long-term viability of the farming industry. This talk will present the utilisation of the model to inform an optimised commercial prototype that will create a business case for a proposed project, drawing on our existing small-scale bioenergy experience and system maturity, using woody waste. Novel aspects of a proposed demonstration project are solar thermal energy boost and high-efficiency heat engine, enhancing overall project commerciality. A set of optimal and low-cost thermo-chemical processes, i.e., catalytic pyrolysis, catalytic reforming, and water-gas shift reaction process, will be adopted to produce hydrogen, which can be used to produce renewable NH3 fertiliser and green electricity. Biochar can be used for soil improvement. The work will be carried out using a pilot-scale fixed-bed pyrolysis reactor and industrial-scale distillation and hydrotreatment processes. The challenges faced will also be presented in this talk.
