Mohsen Ali Mandegari

A critical review on biomass gasification, co-gasification, and their environmental assessments

Gasification is an efficient process to obtain valuable products from biomass with several potential applications, which has received increasing attention over the last decades. Further development of gasification technology requires innovative and economical gasification methods with high efficiencies. Various conventional mechanisms of biomass gasification as well as new technologies are discussed in this paper. Furthermore, co-gasification of biomass and coal as an efficient method to protect the environment by reduction of greenhouse gas (GHG) emissions has been comparatively discussed. In fact, the increasing attention to renewable resources is driven by the climate change due to GHG emissions caused by the widespread utilization of conventional fossil fuels, while biomass gasification is considered as a potentially sustainable and environmentally-friendly technology. Nevertheless, social and environmental aspects should also be taken into account when designing such facilities, to guarantee the sustainable use of biomass. This paper also reviews the life cycle assessment (LCA) studies conducted on biomass gasification, considering different technologies and various feedstocks.

Multi-product biorefineries from lignocelluloses: a pathway to revitalisation of the sugar industry?

BackgroundDriven by a range of sustainability challenges, e.g. climate change, resource depletion and expanding populations, a circular bioeconomy is emerging and expected to evolve progressively in the coming decades. South Africa along with other BRICS countries (Brazil, Russia, India and China) represents the emerging bioeconomy and contributes significantly to global sugar market. In our research, South Africa is used as a case study to demonstrate the sustainable design for the future biorefineries annexed to existing sugar industry. Detailed techno-economic evaluation and Life Cycle Assessment (LCA) were applied to model alternative routes for converting sugarcane residues (bagasse and trash) to selected biofuel and/or biochemicals (ethanol, ethanol and lactic acid, ethanol and furfural, butanol, methanol and Fischer–Tropsch synthesis, with co-production of surplus electricity) in an energy self-sufficient biorefinery system.ResultsEconomic assessment indicated that methanol synthesis with an internal rate of return (IRR) of 16.7% and ethanol–lactic acid co-production (20.5%) met the minimum investment criteria of 15%, while the latter had the lowest sensitivity to market price amongst all the scenarios. LCA results demonstrated that sugarcane cultivation was the most significant contributor to environmental impacts in all of the scenarios, other than the furfural production scenario in which a key step, a biphasic process with tetrahydrofuran solvent, had the most significant contribution.ConclusionOverall, the thermochemical routes presented environmental advantages over biochemical pathways on most of the impact categories, except for acidification and eutrophication. Of the investigated scenarios, furfural production delivered the inferior environmental performance, while methanol production performed best due to its low reagent consumption. The combined techno-economic and environmental assessments identified the performance-limiting steps in the 2G biorefinery design for sugarcane industry and highlighted the technology development opportunities under circular bioeconomy context.

Economic and environmental assessment of cellulosic ethanol production scenarios annexed to a typical sugar mill

In this work different biorefinery scenarios were investigated, concerning the co-production of bioethanol and electricity from available lignocellulose at a typical sugar mill, as possible extensions to the current combustion of bagasse for steam and electricity production and burning trash on-filed. In scenario 1, the whole bagasse and brown leaves is utilized in a biorefinery and coal is burnt in the existing inefficient sugar mill boiler. Scenario 2 & 3 are assumed with a new centralized CHP unit without/with coal co-combustion, respectively. Also, through scenarios 4 & 5, the effect of water insoluble loading were studied. All scenarios provided energy for the sugarmill and the ethanol plant, with the export of surplus electricity. Economic analysis determined that scenario 1 was the most viable scenario due to less capital cost and economies-of scale. Based on Life Cycle Assessment (LCA) results, scenario 2 outperformed the other scenarios, while three scenarios showed lower contribution to environmental burdens than the current situation.

Techno-economic comparison of biojet fuel production from lignocellulose, vegetable oil and sugar cane juice.

In this study, a techno-economic comparison was performed considering three processes (thermochemical, biochemical and hybrid) for production of jet fuel from lignocellulosic biomass (2G) versus two processes from first generation (1G) feedstocks, including vegetable oil and sugar cane juice. Mass and energy balances were constructed for energy self-sufficient versions of these processes, not utilising any fossil energy sources, using ASPEN Plus® simulations. All of the investigated processes obtained base minimum jet selling prices (MJSP) that is substantially higher than the market jet fuel price (2-4 fold). The 1G process which converts vegetable oil, obtained the lowest MJSPs of

Exergy Performance Analysis and Optimization of a Desiccant Wheel System

2.22/kg jet fuel while the two most promising 2G processes- the thermochemical (gasification and Fischer-Tropsch synthesis) and hybrid (gasification and biochemical upgrading) processes- reached MJSPs of

Integrated techno-economic and environmental analysis of butadiene production from biomass

2.44/kg and

Recent trends on techno-economic assessment (TEA) of sugarcane biorefineries

2.50/kg jet fuel, respectively. According to the economic sensitivity analysis, the feedstock cost and fixed capital investment have the most influence on the MJSP.

Multi-criteria analysis of a biorefinery for co-production of lactic acid and ethanol from sugarcane lignocellulose

This paper focused on the exergy analysis and optimization of a dehumidification desiccant wheel (DW) system. A two-dimensional unsteady state numerical model was developed for simulation of the heat and mass transfer phenomena in a representative channel of a DW matrix. The DW mathematical model was validated using a series of experimental data and parametric studies were conducted to investigate the effects of operating parameters on the DW system performance. Exergy parameters were also studied and adopted to predict the total inlet–outlet exergy and exergy destruction, as well as exergy effectivenesses. Furthermore, a new exergy effectiveness parameter was introduced based on the concept of dehumidification. Parametric studies were carried out to characterize the optimal performance of the overall system regarding exergy destruction and exergy dehumidification effectivenesses. The results demonstrate that electrical power consumption, regeneration heat, and heat and mass transfer between air and desiccant are the main sources of exergy destruction. The optimization calculation shows that at the lowest process air velocity (up = 0.2 m/s), lowest DW rotational speed (NDW = 4 Rph), highest regeneration air temperature (Ta,r,in = 140 °C), and moderate regeneration air velocity (ur = 1.7 m/s), minimum exergy destruction occurs. The optimal value of the parameters proves that, when exergy destruction effectiveness is selected as the objective function, the only regeneration air velocity is decision variable of optimization and operational limits impose on the other parameters.

Exergetic diagnosis and performance analysis of a typical sugar mill based on Aspen Plus ® simulation of the process

In this study, lignocellulose biorefineries annexed to a typical sugar mill were investigated to produce either ethanol (EtOH) or 1,3-butadiene (BD), utilizing bagasse and trash as feedstock. Aspen simulation of the scenarios were developed and evaluated in terms of economic and environmental performance. The minimum selling prices (MSPs) for bio-based BD and EtOH production were 2.9-3.3 and 1.26-1.38-fold higher than market prices, respectively. Based on the sensitivity analysis results, capital investment, Internal Rate of Return and extension of annual operating time had the greatest impact on the MSP. Monte Carlo simulation demonstrated that EtOH and BD productions could be profitable if the average of ten-year historical price increases by 1.05 and 1.9-fold, respectively. The fossil-based route was found inferior to bio-based pathway across all investigated environmental impact categories, due to burdens associated with oil extraction.

Exergy analysis of a lignocellulosic-based biorefinery annexed to a sugarcane mill for simultaneous lactic acid and electricity production

Sustainability challenges, e.g., climate change, resource depletion, and expanding populations, have triggered a swift move towards a circular bio-economy which is expected to evolve progressively in the coming decades. However, the transition from a fossil fuel-based economy to a bio-based economy requires the exploitation of scientific innovations and step changes in the infrastructure of chemical industry. Biorefineries have been extensively investigated for biofuel production from first and second generation feedstocks, whereas some research activities have been conducted on production of biochemical and biopolymers from renewable resources. Techno-economic evaluation of diverse technologies for production of biofuels and biochemical is a crucial step for decision making in the development of bio-economy. This contribution focuses on the economic studies carried out on biorefineries converting sugarcane bagasse, due to its availability and importance in the South African context, into value-added products. Recent studies on biofuel production via biochemical pathway, e.g., ethanol, butanol, or thermochemical pathway, e.g., methanol and bio jet fuel as well as production of biochemicals with high market demands and diverse applications such as lactic acid, succinic acid, and xylitol have been briefly reviewed. In addition, an overview on the production of biopolymers such as polyl-lactic acid and bio-based monomers, i.e., butanediol, from sugarcane bagasse is reported.