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During the COVID-19 pandemic, more than 24 billion pieces of surgical mask waste (WM) were generated in the EU region, with an acute shortage of their management and recycling. Pyrolysis and gasification are among the most promising treatments that were proposed to dispose of WMs and convert them into pyrolysis oil and hydrogen-rich syngas. This work aimed to investigate the techno-economic analysis (TEA) of both treatments in order to assess the feasibility of scaling up. The TEA was carried out using a discounted cash flow model and its data were collected from practical experiments conducted using a fluidised bed pyrolysis reactor and bubbling fluidised bed gasifier system with a capacity of 0.2 kg/h and 1 kg/h, respectively, then upscaling to one tonne/h. The technological evaluation was made based on the optimal conditions that could produce the maximum amount of pyrolysis oil (42.3%) and hydrogen-rich syngas (89.7%). These treatments were also compared to the incineration of WMs as a commercial solution. The discounted payback, simple payback, net present value (NPV), production cost, and internal rate of return (IRR) were the main indicators used in the economic feasibility analysis. Sensitivity analysis was performed using SimLab software with the help of Monte Carlo simulations. The results showed that the production cost of the main variables was estimated at 45.4 EUR/t (gate fee), 71.7 EUR/MWh (electricity), 30.5 EUR/MWh (heat), 356 EUR/t (oil), 221 EUR/t (gaseous), 237 EUR/t (char), and 257 EUR/t (syngas). Meanwhile, the IRR results showed that gasification (12.51%) and incineration (7.56%) have better economic performance, while pyrolysis can produce less revenue (1.73%). Based on the TEA results, it is highly recommended to use the gasification process to treat WMs, yielding higher revenue. [ABSTRACT FROM AUTHOR]

Hydrogen is a prominent clean fuel option for combatting global warming and producing low-emission, ecologically friendly electricity. Consequently, the proton exchange membrane water electrolysis (PEMWE) hydrogen refueling station has undergone thorough economic and environmental analysis. This work intends to fill the gap by presenting the influence of various operating circumstances and design parameters on the economic and environmental aspects of PEMWE based on various behaviors and features (I–V curve) under various scenarios. Profitability analysis (PA) is performed in terms of the net present value (NPV), discounted payback period (DPBP), benefit-cost ratio (BCR), and internal rate of return (IRR) from cumulative discounted cash flow diagrams (CFD). Also, sensitivity analysis (SA) is conducted to assess the impact of different economic factors, while simultaneously establishing CO 2 footprint guidelines for optimal operating and design conditions. The findings highlight that enhancing economic feasibility and reducing environmental concerns are simultaneously achievable by increasing cathode pressure, operating temperature, and decreasing membrane thickness. At membrane thicknesses over 100 μm, the project becomes unprofitable and inefficient at 1.85 V. PEMWE becomes more valuable and sustainable with a current density of 12,000 A/m2 or higher, but it releases more CO 2 emissions. Hence, utilizing excess renewable electricity in PEMWE addresses environmental concerns and enhances the overall ecological sustainability of hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design of an integrated catalytic deoxygenation and hydrothermal gasification was performed. • Using experimental data, a high-fidelity process model was created with Aspen Plus. • Exergy analysis results showed that the deoxygenation reactor's exergy efficiencies are superior. • Equipment and raw material costs have superior effect influences on economic viability. Several technologies have been developed to produce sustainable aviation fuel (SAF), the hydroprocessing of esters and fatty acids (HEFA) representing one of the most mature pathways. Although HEFA has been widely adopted by industry, this pathway is mainly reliant on the hydrodeoxygenation (HDO) reaction, which requires large amounts and high pressures of hydrogen gas that reduces the cost-effectiveness of the process. In this study, the economic, environmental, and exergy analyses of two alternative scenarios for the catalytic production of SAF were considered. In both scenarios, SAF is produced through the catalytic deoxygenation of tall oil fatty acid (TOFA) via decarboxylation/decarbonylation (deCO x) – an approach requiring smaller amounts and lower pressures of hydrogen, feedstocks of lower purity and cost, and simpler supported metal catalysts relative to HDO. The material and energy balance was calculated using Aspen Plus process simulation software. Scenario 1 comprises a plant in which the catalytic deoxygenation of TOFA via deCO x is performed using hydrogen gas obtained commercially, while scenario 2 integrates catalytic deoxygenation with a plant that produces hydrogen gas via hydrothermal gasification. The study revealed that both scenarios were economically feasible relative to other pathways for SAF production, with the minimum fuel selling price (MFSP) of scenario 2 (USD$ 0.39/L) being lower than that of scenario 1 (USD$ 0.62/L). In addition to being the most economically viable, scenario 2 was also found to be preferable from an environmental standpoint since it also shows a lower global warming potential (GWP). Discounted cash flow analysis (DCFA) was used to determine other economic indicators such as net present value (NPV), internal rate of return (IRR), net rate of return (NRR) and payback period (PBP), which was estimated to be approximately 3 years for both scenarios. Finally, sensitivity analysis confirms that the raw materials and equipment purchase costs have the greatest impact on the MFSP. [ABSTRACT FROM AUTHOR]

Research in multiple internal rate of return (MROR) has mainly focused on three areas: uniqueness, conditions where MROR occur, and solutions to MROR. In an attempt to solve for MROR, researchers have assumed that the occurrence of MROR is prevalent and thus a solution is direly needed. This article examines the probability that positive MROR would occur when variation is incorporated into the cash flow and the probability of getting positive MROR when multiple sign-change cash flow is generated. Results show that the probability of positive MROR occurring in multiple sign-change cash flows is relatively low and potentially a rare event. [ABSTRACT FROM PUBLISHER]

• The state of São Paulo offers ten potential scenarios for the establishment of biorefineries. • Eucalyptus residues are a promising feedstock that produces 71,000 tons of bio-oil/year. • The minimum selling price of bio-oil varies according to plant capacities between from $11.6 to 19.3/GJ. • The minimum selling price of bio-oil is particularly sensitive to plant capacity and yield. • Co-processing bio-oil with vacuum gasoil can contribute 3.4 % of total "green fuel" in Brazil. Forestry residue is potentially useful for obtaining bio-oil and its by-products (biochar, syngas, and acid-rich aqueous extract) via fast pyrolysis. As such, we carried out a techno-economic analysis of both the production of bio-oil from Eucalyptus grandis residues (ER) and their availability in the state of São Paulo, Brazil. Discounted cash flow was used to calculate the minimum selling price (MSP) of bio-oil. Georeferencing identified the location of 20 Eucalyptus plantations, ten of which were selected due to their better economic performance. These ten plantations were potentially able to produce 59 million L/year of bio-oil. The economic analysis of the future biorefineries showed that an MSP of 11.6–19.3 $ (US)/GJ could support the processing of 60,000–5,000 tons/year of ER. A simulation of a large biorefinery revealed a capital investment (CAPEX) of around 6 M$ (US), reaching an operating expenditure peak of approximately 3 M$/year. The sensitivity analysis identified that plant capacity had the most significant impact on MSP, while the by-products (acid extract and biochar) lowered this by 22 %. The large biorefinery simulated using the Monte Carlo method had an 80 % chance of reaching a net present value (NPV) > 0, and an 80 % probability of reaching an internal rate of return (IRR) > 10 %. This study demonstrated that the production of bio-oils by the ten simulated centralized biorefineries is economically viable based on the NPV and IRR indicators. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal carbonization can readily convert paunch waste to value-added products. • Process modelling indicates that pre-heater and dryer are the main energy consumer. • Hydrothermal carbonization technology development is challenged by reactor high cost. • Treating dewatered paunch waste is more commercially viable despite lower conversion. • Economic viability is highly sensitive to LHSV of reactor and economic assumptions. In this study, dewatered and raw paunch waste, with 15 and 3 wt% total solids respectively, generated at abattoirs was hydrothermally carbonised under subcritical water conditions. Higher solids content was found to produce higher hydrochar yield (i.e. 53% for 15 wt% compared to 33.5% for 3 wt%) at similar operating conditions of 10 bar and 240 °C for 5 min. The morphological differences were noted via Scanning Electron Microscopy (SEM) in the hydrochar samples, and the surface area for processing raw paunch waste was found to be 68.1 m2 g−1 compared to 10.8 m2 g−1 in case of dewatered paunch waste. The light bio-oil was mostly composed of phenolic compounds while the heavy bio-oil mainly contained long chain fatty acids and their esters. Following the experimental work, a full-scale ASPEN Plus process model was developed for a typical abattoir generating 27 tonne dry paunch waste per day. Pre-heater and hydrochar dryer contributed to 73% and 57% of the total energy for processing raw and dewatered paunch waste, respectively, because of the high moisture content of the feedstock and hydrochar. After the equipment sizing and estimation of capital and operating costs, the discounted cash flow analysis was performed using the Nth-Plant financing assumptions. It was concluded that treating dewatered paunch waste is preferable as it: needed a smaller reactor i.e. lower overall initial investment, was less sensitive to bio-oil price, and improved the net present value over a period of 30 years to $2.8 MM. Besides the liquid hourly speed velocity, its commercial viability is highly sensitive to internal rate of return and existence of hydrochar dryer. [ABSTRACT FROM AUTHOR]

Lignocellulose biorefineries process biomass into 'green' chemicals and bioenergy and play a key role in sustainable bio-economies. Using sugarcane bagasse and trash feedstocks, biorefineries were simulated in Aspen Plus ® v 8.6 to generate mass and energy balances. Four scenarios with electricity and furfural as common products were generated. Scenario A in addition produced high volume, low value levulinic acid whilst scenarios B1 and B2 generated low volume, high value levulinic acid at varied feedstock capacities. Scenario C produced low volume, high value levulinic acid and bulk gamma valerolactone. The four biorefineries were also compared to a combined heat and power plant that only produced steam and electricity. Aspen Plus ® Economic Analyser and a discounted cash flow rate of return methodology were used to determine the economic feasibility of the bioenergy self-sufficient biorefineries annexed to a conventional South African sugar mill. Levulinic acid production via the Biofine process makes economic sense when produced for niche markets, due to the anticipated decrease in market prices when production volumes increase. Scenario (C) co-producing a low volume of levulinic acid (0.15 t h−1) together with 3.3 t h−1 furfural, electricity (14 MWh) and 6.8 t h−1 gamma valerolactone, was the most profitable. It attained an internal rate of return of 23% and 253 US$ million net present value at a 9.7% hurdle rate by matching chemicals' production volumes to market demands, to maintain high market prices for multiple revenue streams. • Techno-economics of lignocellulose biorefineries via chemical means were assessed. • Economies of scale effects and extra returns from multiple products raised profits. • Scenario with specialty levulinic acid and bulk gamma valerolactone was profitable. [ABSTRACT FROM AUTHOR]