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Techno-economic evaluation of a novel biomass pyrogasification process with an integrated sorption-shift system; A process for the conversion of waste to high-quality biochar and hydrogen with carbon capture and hydrogen upgrading

Buiteveld, J. (2021) Techno-economic evaluation of a novel biomass pyrogasification process with an integrated sorption-shift system; A process for the conversion of waste to high-quality biochar and hydrogen with carbon capture and hydrogen upgrading.

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Abstract:A novel system for the production of high quality biochar and high purity hydrogen out of biomass is developed. The proposed system uses a combination of pyrolysis, steam reforming and a novel Sorption Enhanced Water Gas Shift (SEWGS) system based on Calcium Looping (CaL). This system uses calcium oxide (CaO) for CO2 capture and to shift the Water-Gas-Shift (WGS) reaction into the direction of hydrogen. An Aspen Plus model is constructed to simulate reactor stoichiometry, develop efficient heat integration and for system analysis and evaluation. Process simulations show an overall maximum energy efficiency of 74.9% based on chemical energy, a high quality biochar is produced: HHV=34.2 MJ/kg as well as high quality hydrogen: 99.7% purity. Per ton of dry and ash free biomass input (HHV = 18.0 MJ/kg) the system produces 59 kg of hydrogen and 186 kg of biochar. A financial model is designed based on cash flow simulations. Heat exchanger size optimization is performed with respect to cost efficiency, resulting in a system with a levelized cost of hydrogen of €4.01 per kg combined with levelized cost of biochar of €668 per ton. Compared to other sustainable high purity hydrogen production techniques the designed system is compatible and produced high purity hydrogen at significantly lower cost compared to hydrogen production by electrolysis. A societal analysis is performed which identified the analyzed technology as fitting with future biomass based polices of western European countries. In Europe and in the Netherlands there is sustainable biomass potential for the developed technology. A model is designed for CO2 footprint calculations, which shows a negative CO2 footprint -1041 kg CO2 per ton of biomass input: the process has the potential to reverse global warming. Further process optimizations and development is recommended with respect to better understanding of CaL based SEWGS, especially with respect to gain better understanding of kinetics. A research proposal is written for a (European) research project to further investigate SEWGS reactor mechanics. Upscaling of auger reactors for slow pyrolysis and implementation of oxy-fuel combustion for CaO regeneration are subjects which require further research. The oxy-fuel system is (shortly) analyzed, and shows a large future potential, especially in a combined process configuration with water electrolysis for hydrogen production. This research shows that a pyrogasification sorption enhanced water gas shift system can be a technical, economical and societal feasible technology which delivers high quality sustainable products which fits within the needs of the future sustainable economy
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:43 environmental science, 52 mechanical engineering, 58 process technology
Programme:Mechanical Engineering MSc (60439)
Link to this item:http://purl.utwente.nl/essays/85770
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