9 research outputs found
Performance assessment of biofuel production via biomass fast pyrolysis and refinery technologies
Biofuels have been identified as one of several GHG emission strategies to
reduce the use of fossil fuels in the transport sector. Fast pyrolysis of biomass is
one approach to producing second generation biofuels. The bio-oil product of fast
pyrolysis can be upgraded into essential gasoline and diesel range products with
conventional refinery technologies. Thus, it is important to assess their techno-
economic and environmental performance at an early stage prior to
commercialisation. This research was conducted with the goal of evaluating and
comparing the techno-economic and environmental viability of the production of
biofuels from fast pyrolysis of biomass and upgrading of bio-oil via two refinery
technologies, viz. hydroprocessing and zeolite cracking. In order to achieve this
aim, process models of fast pyrolysis of biomass and bio-oil upgrading via
hydroprocessing and zeolite cracking were developed. The fast pyrolysis model
was based on multi-step kinetic models. In addition, lumped kinetic models of the
hydrodeoxygenation reactions of bio-oil were implemented. The models were
verified against experimental measurements with good prediction and formed the
foundation for the development of a 72 t/day fast pyrolysis plant model in Aspen
PlusĀ®. Several strategies were proposed for the two pathways to enhance energy
efficiency and profitability. All in all, the results revealed that the hydroprocessing
route is 16% more efficient than the zeolite cracking pathway. Moreover, the
hydroprocessing route resulted in a minimum fuel selling price of 15% lower than
that from the zeolite cracking pathway. Sensitivity analysis revealed that the
techno-economic and environmental performance of the both pathways depends
on several process, economic and environmental parameters. In particular,
biofuel yield, operating cost and income tax were identified as the most sensitive
techno-economic parameters, while changes in nitrogen feed gas to the pyrolysis
reactor and fuel yield had the most environmental impact. It was concluded that
hydroprocessing is a more suitable upgrading pathway than zeolite cracking in
terms of economic viability, energy efficiency, and GHG emissions per energy
content of fuel produced
Techno-economic performance analysis of biofuel production and miniature electric power generation from biomass fast pyrolysis and bio-oil upgrading
The techno-economic performance analysis of biofuel production and electric power generation from biomass fast pyrolysis and bio-oil hydroprocessing is explored through process simulation. In this work, a process model of 72 MT/day pine wood fast pyrolysis and bio-oil hydroprocessing plant was developed with rate based chemical reactions using Aspen PlusĀ® process simulator. It was observed from simulation results that 1 kg sā1 pine wooddb generate 0.64 kg sā1 bio-oil, 0.22 kg sā1 gas and 0.14 kg sā1 char. Simulation results also show that the energy required for drying and fast pyrolysis operations can be provided from the combustion of pyrolysis by-products, mainly, char and non-condensable gas with sufficient residual energy for miniature electric power generation. The intermediate bio-oil product from the fast pyrolysis process is upgraded into gasoline and diesel via a two-stage hydrotreating process, which was implemented by a pseudo-first order reaction of lumped bio-oil species followed by the hydrocracking process in this work. Simulation results indicate that about 0.24 kg sā1 of gasoline and diesel range products and 96 W of electric power can be produced from 1 kg sā1 pine wooddb. The effect of initial biomass moisture content on the amount of electric power generated and the effect of biomass feed composition on product yields were also reported in this study. Aspen Process Economic AnalyserĀ® was used for equipment sizing and cost estimation for an nth plant and the product value was estimated from discounted cash flow analysis assuming the plant operates for 20 years at a 10% annual discount rate. Economic analysis indicates that the plant will require Ā£16.6 million of capital investment and product value is estimated at Ā£6.25/GGE. Furthermore, the effect of key process and economic parameters on product value and the impact of electric power generation equipment on capital cost and energy efficiency were also discussed in this study
Comparative evaluation of GHG emissions from the use of Miscanthus for bio-hydrocarbon production via fast pyrolysis and bio-oil upgrading
This study examines the GHG emissions associated with producing bio-hydrocarbons via fast pyrolysis of Miscanthus. The feedstock is then upgraded to bio-oil products via hydroprocessing and zeolite cracking. Inventory data for this study were obtained from current commercial cultivation practices of Miscanthus in the UK and state-of-the-art process models developed in Aspen PlusĀ®. The system boundary considered spans from the cultivation of Miscanthus to conversion of the pyrolysis-derived bio-oil into bio-hydrocarbons up to the refinery gate. The Miscanthus cultivation subsystem considers three scenarios for soil organic carbon (SOC) sequestration rates. These were assumed as follows: (i) excluding (SOC), (ii) low SOC and (iii) high (SOC) for best and worst cases. Overall, Miscanthus cultivation contributed moderate to negative values to GHG emissions, from analysis of excluding SOC to high SOC scenarios. Furthermore, the rate of SOC in the Miscanthus cultivation subsystem has significant effects on total GHG emissions. Where SOC is excluded, the fast pyrolysis subsystem shows the highest positive contribution to GHG emissions, while the credit for exported electricity was the main ānegativeā GHG emission contributor for both upgrading pathways. Comparison between the bio-hydrocarbons produced from the two upgrading routes and fossil fuels indicates GHG emission savings between 68% and 87%. Sensitivity analysis reveals that bio-hydrocarbon yield and nitrogen gas feed to the fast pyrolysis reactor are the main parameters that influence the total GHG emissions for both pathways
Heat integration for bio-oil hydroprocessing coupled with aqueous phase steam reforming
AbstractOptimized heat exchanger networks can improve process profitability and minimize emissions. The aim of this study is to assess the heat integration opportunities for a hypothetical bio-oil hydroprocessing plant integrated with a steam reforming process via pinch technology. The bio-oil hydroprocessing plant was developed with rate based chemical reactions using ASPEN PlusĀ® process simulator. The base case is a 1600kg/h bio-oil hydroprocessing plant, which is integrated with a steam reforming process of the bio-oil aqueous phase. The impact of the reformer steam to carbon ratio on energy targets was analysed, revealing that significant energy savings can be achieved at different process variations. Aspen Energy Analyzerā¢ was employed to design the heat exchanger network. Two heat exchanger network designs are considered. The optimum design reveals that the second hydrodeoxygenation reactor effluent can preheat the bio-oil feed with minimal capital cost implication and achieve similar energy targets compared with the alternative design. The economic and environmental implications of the two heat exchanger network designs on product value were also evaluated
Techno-economic analysis of biofuel production via bio-oil zeolite upgrading: An evaluation of two catalyst regeneration systems
Biofuels have been identified as a mid-term GHG emission abatement solution for decarbonising the transport sector. This study examines the techno-economic analysis of biofuel production via biomass fast pyrolysis and subsequent bio-oil upgrading via zeolite cracking. The aim of this study is to compare the techno-economic feasibility of two conceptual catalyst regeneration configurations for the zeolite cracking process: (i) a two-stage regenerator operating sequentially in partial and complete combustion modes (P-2RG) and (ii) a single stage regenerator operating in complete combustion mode coupled with a catalyst cooler (P-1RGC). The designs were implemented in Aspen PlusĀ® based on a hypothetical 72 t/day pine wood fast pyrolysis and zeolite cracking plant and compared in terms of energy efficiency and profitability. The energy efficiencies of P-2RG and P-1RGC were estimated at 54% and 52%, respectively with corresponding minimum fuel selling prices (MFSPs) of Ā£7.48/GGE and Ā£7.20/GGE. Sensitivity analysis revealed that the MFSPs of both designs are mainly sensitive to variations in fuel yield, operating cost and income tax. Furthermore, uncertainty analysis indicated that the likely range of the MFSPs of P-1RGC (Ā£5.81/GGE Ā£11.63/GGE) at 95% probability was more economically favourable compared with P-2RG, along with a penalty of 2% reduction in energy efficiency. The results provide evidence to support the economic viability of biofuel production via zeolite cracking of pyrolysis-derived bio-oil
Heat integration for bio-oil hydroprocessing coupled with aqueous phase steam reforming
Optimized heat exchanger networks can improve process profitability and minimize emissions. The aim of this study is to assess the heat integration opportunities for a hypothetical bio-oil hydroprocessing plant integrated with a steam reforming process via pinch technology. The bio-oil hydroprocessing plant was developed with rate based chemical reactions using ASPEN PlusĀ® process simulator. The base case is a 1600 kg/h bio-oil hydroprocessing plant, which is integrated with a steam reforming process of the bio-oil aqueous phase. The impact of the reformer steam to carbon ratio on energy targets was analysed, revealing that significant energy savings can be achieved at different process variations. Aspen Energy Analyzerā¢ was employed to design the heat exchanger network. Two heat exchanger network designs are considered. The optimum design reveals that the second hydrodeoxygenation reactor effluent can preheat the bio-oil feed with minimal capital cost implication and achieve similar energy targets compared with the alternative design. The economic and environmental implications of the two heat exchanger network designs on product value were also evaluated
Social Hotspot Analysis and Trade Policy Implications of the Use of Bioelectrochemical Systems for Resource Recovery from Wastewater
Bioelectrochemical systems (BESs) have been catalogued as a technological solution to three pressing global challenges: environmental pollution, resource scarcity, and freshwater scarcity. This study explores the social risks along the supply chain of requisite components of BESs for two functionalities: (i) copper recovery from spent lees and (ii) formic acid production via CO2 reduction, based on the UK’s trade policy. The methodology employed in this study is based on the UNEP/SETAC guidelines for social life-cycle assessment (S-LCA) of products. Relevant trade data from UN COMTRADE database and generic social data from New Earth’s social hotspot database were compiled for the S-LCA. The results revealed that about 75% of the components are imported from the European Union. However, the social risks were found to vary regardless of the magnitude or country of imports. “Labour and Decent Work” was identified as the most critical impact category across all countries of imports, while the import of copper showed relatively higher risk than other components. The study concludes that BESs are a promising sustainable technology for resource recovery from wastewater. Nevertheless, it is recommended that further research efforts should concentrate on stakeholder engagement in order to fully grasp the potential social risks
Comparative evaluation of GHG emissions from the use of Miscanthus for bio-hydrocarbon production via fast pyrolysis and bio-oil upgrading
This study examines the GHG emissions associated with producing bio-hydrocarbons via fast pyrolysis of Miscanthus. The feedstock is then upgraded to bio-oil products via hydroprocessing and zeolite cracking. Inventory data for this study were obtained from current commercial cultivation practices of Miscanthus in the UK and state-of-the-art process models developed in Aspen PlusĀ®. The system boundary considered spans from the cultivation of Miscanthus to conversion of the pyrolysis-derived bio-oil into bio-hydrocarbons up to the refinery gate. The Miscanthus cultivation subsystem considers three scenarios for soil organic carbon (SOC) sequestration rates. These were assumed as follows: (i) excluding (SOC), (ii) low SOC and (iii) high (SOC) for best and worst cases. Overall, Miscanthus cultivation contributed moderate to negative values to GHG emissions, from analysis of excluding SOC to high SOC scenarios. Furthermore, the rate of SOC in the Miscanthus cultivation subsystem has significant effects on total GHG emissions. Where SOC is excluded, the fast pyrolysis subsystem shows the highest positive contribution to GHG emissions, while the credit for exported electricity was the main ānegativeā GHG emission contributor for both upgrading pathways. Comparison between the bio-hydrocarbons produced from the two upgrading routes and fossil fuels indicates GHG emission savings between 68 and 87%. Sensitivity analysis reveals that bio-hydrocarbon yield and nitrogen gas feed to the fast pyrolysis reactor are the main parameters that influence the total GHG emissions for both pathways