Gallon Of Gasoline Equivalent Research Articles

Techno-economic analysis of bioplastic and biofuel production from a high-ash microalgae biofilm cultivated in effluent from a municipal anaerobic digester

Rotating Algae Biofilm Reactors (RABRs) are a promising technology for efficient treatment of wastewater and production of algae-based bioproducts. However, RABR-grown algae can contain a high content of ash (30–60 wt%, dry basis), which influences the technical and economic feasibility of bioproduct conversion processes. In this report, experimental studies and economic analysis were conducted to compare different processes for bioproduct conversion of a high-ash microalgae biofilm grown using a RABR treating 0.6 million gallons per day of anaerobic digestion centrate at the Central Valley Water Reclamation Facility in Salt Lake City, UT. Process and economic models were developed and compared for three conversion processes: 1) the production of bioplastics, 2) the production of bioplastics with a lipid-extraction pretreatment, and 3) the production of biocrude via hydrothermal liquefaction. Techno-economic analysis was performed for each conversion process, including three cases for algae productivity: 231, 391, and 577 metric tons per year (dry basis). The calculated value for the minimum plastic selling price (MPSP) of bioplastics produced from algae ranges from $4050 to $3520 per metric ton based on the baseline and final productivity cases of the RABR, respectively. The extraction of lipids in addition to bioplastic production results in an MPSP of $4570 to $4000 per metric ton for the same productivity cases. The relatively small production scale and complex processing for hydrothermal liquefaction results in a minimum fuel selling price of the biocrude of $5.32 per gallon of gasoline equivalent. The conversion process for bioplastic production from whole algae has the highest income:expense ratio and the most cost-competitive pricing of the three modeled processes.

Substitutional phosphorus doping stimulates strong metal-support interactions for anion exchange membrane based alkaline seawater electrolysis

The development of electrocatalysts with high catalytic activity and resistant to chlorine has become crucial for the large-scale implementation of seawater electrolysis. Here, the strong metal support interaction (SMSI) between Pt and NiMoO4 is enhanced by substitutional P atom-doping (P-Pt/NiMoO4@NF) to optimize the metal surrounding environment, realizing the efficient and anticorrosive seawater electrolysis. Density functional theory (DFT) reveals that substitutional P atom-doping can adjust the electronic structure to optimize the hydrogen adsorption free energy (ΔGH*) and decrease the adsorption energy of Cl- for the HER process. Benefiting from the SMSI caused by substitutional P atom-doping, the prepared P-Pt/NiMoO4@NF catalyst achieves a current density of 1.0 A cm−2 at an ultra-low overpotential of only 80 mV, surpassing the most reported Pt-based electrocatalysts. More importantly, in the anion exchange membrane (AEM) electrolyzer, the catalyst used as the cathode can drive 500 mA cm−2 under industrial conditions with only 1.75 V, while running steadily for 120 h, and with high efficiency and low price of H2 per gallon gasoline equivalent (GGE).

Orderly Nanodendritic Nickel Substitute for Raney Nickel Catalyst Improving Alkali Water Electrolyzer.

The development of nonprecious metal catalysts to meet the activity-stability balance at industrial-grade large current densities remains a challenge toward practical alkali-water electrolysis. Here, this work develops an orderly nanodendritic nickel (ND-Ni) catalyst that consists of ultrafine nanograins in chain-likeconformation, which shows both excellent activity and robust stability for large current density hydrogen evolution reaction (HER) in alkaline media, superior to currently applied Raney nickel (R-Ni) catalyst in commercial alkali-water electrolyzer (AWE). The ND-Ni catalyst featured by a three-dimensional (3D) interconnecting microporous structure endows with high specific surface area and excellent conductivity and hydrophilicity, which together afford superior charge/mass transport favorable to HER kinetics at high current densities. An actual AWE with ND-Ni catalyst demonstrates durable water splitting with 1.0 A cm-2 at 1.71V under industrial conditions and renders a record-low power consumption of 3.95kW h Nm-3 with an energy efficiency close to 90%. The hydrogen price per gallon of gasoline equivalent (GGE) is calculated to be ≈$0.95, which is less than the target of $2.0 per GGE by 2026 from the U.S. Department of Energy. The results suggest the feasibility of ND-Ni substitute for R-Ni catalyst in commercial AWE.

A corrosion-resistant RuMoNi catalyst for efficient and long-lasting seawater oxidation and anion exchange membrane electrolyzer

Direct seawater electrolysis is promising for sustainable hydrogen gas (H2) production. However, the chloride ions in seawater lead to side reactions and corrosion, which result in a low efficiency and poor stability of the electrocatalyst and hinder the use of seawater electrolysis technology. Here we report a corrosion-resistant RuMoNi electrocatalyst, in which the in situ-formed molybdate ions on its surface repel chloride ions. The electrocatalyst works stably for over 3000 h at a high current density of 500 mA cm−2 in alkaline seawater electrolytes. Using the RuMoNi catalyst in an anion exchange membrane electrolyzer, we report an energy conversion efficiency of 77.9% and a current density of 1000 mA cm−2 at 1.72 V. The calculated price per gallon of gasoline equivalent (GGE) of the H2 produced is $ 0.85, which is lower than the 2026 technical target of $ 2.0/GGE set by the United Stated Department of Energy, thus, suggesting practicability of the technology.

Techno-economic assessment for the production of algal fuels and value-added products: opportunities for high-protein microalgae conversion

BackgroundMicroalgae possess numerous advantages for use as a feedstock in producing renewable fuels and products, with techno-economic analysis (TEA) frequently used to highlight the economic potential and technical challenges of utilizing this biomass in a biorefinery context. However, many historical TEA studies have focused on the conversion of biomass with elevated levels of carbohydrates and lipids and lower levels of protein, incurring substantial burdens on the ability to achieve high cultivation productivity rates relative to nutrient-replete, high-protein biomass. Given a strong dependence of algal biomass production costs on cultivation productivity, further TEA assessment is needed to understand the economic potential for utilizing potentially lower-cost but lower-quality, high-protein microalgae for biorefinery conversion.ResultsIn this work, we conduct rigorous TEA modeling to assess the economic viability of two conceptual technology pathways for processing proteinaceous algae into a suite of fuels and products. One approach, termed mild oxidative treatment and upgrading (MOTU), makes use of a series of thermo-catalytic operations to upgrade solubilized proteins and carbohydrates to hydrocarbon fuels, while another alternative focuses on the biological conversion of those substrates to oxygenated fuels in the form of mixed alcohols (MA). Both pathways rely on the production of polyurethanes from unsaturated fatty acids and valorization of unconverted solids for use as a material for synthesizing bioplastics. The assessment found similar, albeit slightly higher fuel yields and lower costs for the MA pathway, translating to a residual solids selling price of $899/ton for MA versus $1033/ton for MOTU as would be required to support a $2.50/gallon gasoline equivalent (GGE) fuel selling price. A variation of the MA pathway including subsequent upgrading of the mixed alcohols to hydrocarbon fuels (MAU) reflected a required solids selling price of $975/ton.ConclusionThe slight advantages observed for the MA pathway are partially attributed to a boundary that stops at oxygenated fuels versus fungible drop-in hydrocarbon fuels through a more complex MOTU configuration, with more comparable results obtained for the MAU scenario. In either case, it was shown that an integrated algal biorefinery can be economical through optimal strategies to utilize and valorize all fractions of the biomass.

Development of a mobile, pilot scale hydrothermal liquefaction reactor: Food waste conversion product analysis and techno-economic assessment

The purpose of the present work is to investigate the feasibility of hydrothermal liquefaction (HTL) on food waste using a mobile pilot scale reactor and assess its techno-economic potential as a renewable energy technology that can be commercialized in the future. A 35 L pilot scale reactor (0.15 Gal·min−1, 300 °C, and 60 min retention time) resulted in a higher biocrude oil yield than lab scale reactors (29.5 wt% vs 21.9 wt%). Biocrude oil qualities from pilot scale and lab scale HTL showed similar characteristics when comparing the elemental distribution, oil composition, and heating values. Further, techno-economic assessment (TEA) showed that the minimum selling price of the biocrude oil from a base case scenario was $3.48 per gallon gasoline equivalent (GGE). The transportation cost of the feedstock and oil product was compared between onsite and mobile scenarios of HTL reactor operation. The results demonstrated that the mobile HTL reactor was more profitable when the sources of food waste were widely distributed (more than 106 miles). Combined pilot reactor results and assessments in different scenarios could be used to assess the sustainability of the HTL process for future large-scale implementation.

Techno-Economic Analysis of decentralized preprocessing systems for fast pyrolysis biorefineries with blended feedstocks in the southeastern United States

This study evaluated the economic feasibility of fast pyrolysis biorefineries fed with blended pine residues and switchgrass in the Southeastern U.S. with different supply chain design. Previous techno-economic analyses (TEA) have focused on either blended biomass or decentralized preprocessing without investigating the impacts of varied process parameters, technology options, and real-world biomass distribution. This study fills the literature gap by modeling scenarios for different biomass blending ratios, biorefinery and preprocessing site (so-called depot) capacities, and alternative preprocessing technologies. High-resolution, real-world geospatial data were analyzed using Geographic Information Systems to facilitate supply chain design and TEA. For a decentralized system, the minimum fuel selling price (MFSP) of biofuel was $3.92–$4.33 per gallon gasoline equivalent (GGE), while the MFSP for the centralized biorefinery at the same capacities ranged between $3.75–$4.02/GGE. Implementing a high moisture pelleting process depot rather than a conventional pelleting process lowered the MFSP by $0.03–$0.17/GGE. Scenario analysis indicated decreased MFSP with increasing biorefinery capacities but not necessarily with increasing depot size. Medium-size depots (500 OMDT/day) achieved the lowest MFSP. This analysis identified the optimal blending ratios for two preprocessing technologies at varied depot sizes. Counterintuitively, increasing the proportion of higher cost switchgrass reduced the MFSP for large biorefineries (>5000 ODMT/day), but increased the MFSP for small biorefineries (1000–2500 ODMT/day). Although the decentralized systems have a higher MFSP based on current analysis, it has other potential benefits such as mitigated supply chain risks and improved feedstock quality that are difficult to be quantified in this TEA.

Upgrading brown grease for the production of biofuel intermediates

Products from waste streams can reduce the amount of materials going to landfills or being incinerated. Brown grease captured from grease traps or wastewater facilities is produced at approximately 1,500,000 metric tons annually in the United States. Two brown grease samples were characterized from a local collector. Raw brown grease was fermented using Clostridium butyricum to produce butyric acid, achieving a yield of 0.55 butyric acid/g sugars indicating that glycerol and lactic acid were also converted. Hexane extraction of the fermentation broth gave an 81.3% recovery of lipids. Techno-economic analysis calculated a minimum fuel selling price of $1.81 per gallon gasoline equivalent (GGE) for a facility based on a city the size of Denver and a brown grease delivery price of $100 per dry metric ton. Exploiting waste streams as feedstocks can significantly reduce costs to produce fuels and can be brought to scale more rapidly due to their ready availability.

Understanding the role of Fischer–Tropsch reaction kinetics in techno‐economic analysis for co‐conversion of natural gas and biomass to liquid transportation fuels

AbstractWith the increased availability of low‐cost natural gas, the co‐conversion of natural gas and biomass‐to‐liquid fuels has attracted attention from industry due to its potential for improving liquid fuel yields while lowering greenhouse gas emissions. This study provides an understanding of Fischer–Tropsch kinetics, improvements in processing strategies for hydrocarbon production, and of its impact on cost for the co‐conversion of natural gas and biomass‐to‐transportation fuels. Studies that investigate the effect of Fischer–Tropsch reaction kinetics on techno‐economic analysis can be used to develop process models that consider reaction stoichiometry and account for the effect of the paraffin‐to‐olefin ratio. We consider two processing scenarios: (1) one that does not employ a hydrocracker, and (2) the other where a hydrocracker serves as an integral part of the process scheme. Our analysis shows that co‐processing natural gas not only facilitates the economic benefits of converting biomass‐to‐liquid fuels but also facilitates flexibility in process integration. The resulting minimum fuel selling price ranged from $2.47–$3.47/GGE (gallon gasoline equivalent) without the hydrocracker and ranged from $2.17–$3.60/GGE with the inclusion of the hydrocracker, for a 50 million GGE hydrocarbon fuel production facility and for varying blending ratios for biomass from 0–100% with natural gas. The hydrocracker helps to increase the production of diesel and jet fuels substantially, with carbon efficiencies of 50% attained for a chain growth probability of 0.87. The cost penalty comes from the capital expenses of the hydrocracker, and the expense may not be offset with hydrocarbon yield improvement. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Bioalcohol production from acidogenic products via a two-step process: A case study of butyric acid to butanol

This article presents the full study (lab-scale experimental study and large-scale techno-economic analysis) results of a two-step catalytic process for the conversion of organic waste–derived butyric acid to butanol. The two-step process consists of the (1) esterification of butyric acid to methyl butyrate and (2) hydrogenolysis of this methyl butyrate to butanol. The first reaction, esterification of butyric acid, was optimized using carbon-based catalysts. The production of butanol from methyl butyrate via hydrogenolysis was investigated using bimetallic Pt–Co catalysts. The hydrogenolysis of methyl butyrate on these catalysts under optimal conditions of 250 °C, 5 MPa H2, and a feed/catalyst weight ratio of 11.2 led to 54.1% selectivity toward 1-butanol. Based on the experimental results, an integrated process simulation model was developed to determine the economic potential of the two-step production of butanol from butyric acid. Using this model, the techno-economic feasibility of the two-step process was analyzed. The minimum selling price (MSP) of 1-butanol produced from butyric acid using this process was US$ 3.388 per gallon of gasoline equivalent (GGE). This MSP is in the range of recent biofuel market prices of US$ 2.03/GGE to US$ 3.83/GGE.

Assessing the stability and techno-economic implications for wet storage of harvested microalgae to manage seasonal variability

BackgroundSeasonal variation in microalgae production is a significant challenge to developing cost-competitive algae biofuels. Summer production can be three to five times greater than winter production, which could result in winter biomass shortages and summer surpluses at algae biorefineries. While the high water content (80%, wet basis) of harvested microalgae biomass makes drying an expensive approach to preservation, it is not an issue for ensiling. Ensiling relies on lactic acid fermentation to create anaerobic acidic conditions, which limits further microbial degradation. This study explores the feasibility of preserving microalgae biomass through wet anaerobic storage ensiling over 30 and 180 days of storage, and it presents a techno-economic analysis that considers potential cost implications.ResultsHarvested Scenedesmus acutus biomass untreated (anaerobic) or supplemented with 0.5% sulfuric acid underwent robust lactic acid fermentation (lactic acid content of 6–9%, dry basis) lowering the pH to 4.2. Dry matter losses after 30 days ranged from 10.8 to 15.5% depending on the strain and treatment without additional loss over the next 150 days. Long-term storage of microalgae biomass resulted in lactic acid concentrations that remained high (6%, dry basis) with a low pH (4.2–4.6). Detailed biochemical composition revealed that protein and lipid content remained unaffected by storage while carbohydrate content was reduced, with greater dry matter loss associated with greater reduction in carbohydrate content, primarily affecting glucan content. Techno-economic analysis comparing wet storage to drying and dry storage demonstrated the cost savings of this approach. The most realistic dry storage scenario assumes a contact drum dryer and aboveground carbon steel storage vessels, which translates to a minimum fuel selling price (MFSP) of $3.72/gallon gasoline equivalent (GGE), whereas the most realistic wet storage scenario, which includes belowground, covered wet storage pits translates to an MFSP of $3.40/GGE.ConclusionsMicroalgae biomass can be effectively preserved through wet anaerobic storage, limiting dry matter loss to below 10% over 6 months with minimal degradation of carbohydrates and preservation of lipids and proteins. Techno-economic analysis indicates that wet storage can reduce overall biomass and fuel costs compared to drying and dry storage.

Techno-economic analysis of thermal deoxygenation based biorefineries for the coproduction of fuels and chemicals

The economic impact of coproduction of renewable fuels with platform chemicals is determined by assessing thermal deoxygenation (TDO) pathway based biorefineries with two distinct product suites: (1) fuel and furfural (a platform chemical) and (2) fuel and levulinic acid (a platform chemical). Greenfield and brownfield plant site scenarios are considered. Additionally, the economic viability of producing activated carbon from biochar, rather than burning it to produce energy, is assessed. The biorefinery in which wood is converted using the TDO pathway to furfural, renewable fuel, and biochar is found to be a product-driven biorefinery. The production of renewable fuel along with levulinic acid from recycled cardboard via the TDO pathway is determined to be an energy-driven biorefinery. The minimum selling price (MSP) of TDO oil produced in product-driven and energy-driven greenfield biorefineries are estimated at US$17 and US$18 per GJ or US$2.78 and US$2.92 per gallon of gasoline equivalent (GGE), respectively. It is found that capital investment for the product-driven and energy-driven biorefineries can be reduced by 23–27% through integrating the TDO process into an existing pulp and paper facility (brownfield site), provided the infrastructure and assets of pulp and paper mill are well maintained. It has been learned that the synergy arising through co-production of chemicals with fuels and vice versa can facilitate the sustainable production of both renewable fuels as well as platform chemicals. Moreover, there is a need for the development of new less energy intensive separation processes for purifying bio-products.

Formate‐assisted pyrolysis of biomass: an economic and modeling analysis

AbstractAn economic analysis was performed to determine the economic potential and commercialization barriers of producing renewable gasoline and diesel (RGD) fuel blendstocks via formate‐assisted pyrolysis (FAsP) followed by hydrodeoxygenation processes. A process model was simulated using Aspen Plus® to estimate material and energy balances for the conversion of 2000 dry MT per day of pine sawdust. Scenarios were considered for the regeneration of formate salts from either ‐biomass‐derived and natural‐gas‐derived carbon monoxide. The material and energy balances were used to calculate capital and operating costs of RGD fuel production. An economic model was built using capital and operating costs to estimate the minimum selling price (MSP) of RGD fuel. The MSP of RGD fuels were estimated at $4.58 per gallon of gasoline equivalent (GGE) and $4.80 per GGE for natural gas and biomass‐derived CO scenarios, respectively. The total capital investments of these plants were $448 million and $497 million. The feedstock cost was found to be the major cost contributor to the MSP of RGD fuel. Improving FAsP process yields will significantly reduce the production cost of RGD fuel. It has been learned that an increase in deoxygenation of bio‐oil in pyrolysis reactor decreases the capital and operating costs of bio‐oil upgrading to RGD fuel. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd

Combined algal processing: A novel integrated biorefinery process to produce algal biofuels and bioproducts

The development of an integrated biorefinery process capable of producing multiple products is crucial for commercialization of microalgal biofuel production. Dilute acid pretreatment has been demonstrated as an efficient approach to utilize algal biomass more fully, by hydrolyzing microalgal carbohydrates into fermentable sugars, while making the lipids more extractable, and a protein fraction available for other products. Previously, we have shown that sugar-rich liquor could be separated from solid residue by solid–liquid separation (SLS) to produce ethanol via fermentation. However, process modeling has revealed that approximately 37% of the soluble sugars were lost in the solid cake after the SLS. Herein, a Combined Algal Processing (CAP) approach with a simplified configuration has been developed to improve the total energy yield. In CAP, whole algal slurry after acid pretreatment is directly used for ethanol fermentation. The ethanol and microalgal lipids can be sequentially recovered from the fermentation broth by thermal treatment and solvent extraction. Almost all the monomeric fermentable sugars can be utilized for ethanol production without compromising the lipid recovery. The techno-economic analysis (TEA) indicates that the CAP can reduce microalgal biofuel cost by $0.95 per gallon gasoline equivalent (GGE), which is a 9% reduction compared to the previous biorefinery scenario.

Techno-economic analysis of advanced biofuel production based on bio-oil gasification

This paper evaluates the economic feasibility of an integrated production pathway combining fast pyrolysis and bio-oil gasification. The conversion process is simulated with Aspen Plus® for a 2000 metric ton per day facility. Techno-economic analysis of this integrated pathway has been conducted. A total capital investment of $510 million has been estimated and the minimum fuel selling price (MSP) is $5.59 per gallon of gasoline equivalent. The sensitivity analysis shows that the MSP is most sensitive to internal rate of return, fuel yield, biomass feedstock cost, and fixed capital investment. Monte-Carlo simulation shows that MSP for bio-oil gasification would be more than $6/gal with a probability of 0.24, which indicates this pathway is still at high risk with current economic and technical situation.

Getting to low-cost algal biofuels: A monograph on conventional and cutting-edge harvesting and extraction technologies

Among the most formidable challenges to algal biofuels is the ability to harvest algae and extract intracellular lipids at low cost and with a positive energy balance. In this monograph, we construct two paradigms that contrast energy requirements and costs of conventional and cutting-edge Harvesting and Extraction (H&E) technologies. By application of the parity criterion and the moderate condition reference state, an energy–cost paradigm is created that allows 1st stage harvesting technologies to be compared with easy reference to the National Alliance for Advanced Biofuels and Bioproducts (NAABB) target of $0.013/gallon of gasoline equivalent (GGE) and to the U.S. DOE's Bioenergy Technologies Office 2022 cost metrics. Drawing from the moderate condition reference state, a concentration-dependency paradigm is developed for extraction technologies, making easier comparison to the National Algal Biofuels Technology Roadmap (NABTR) target of less than 10% total energy. This monograph identifies cost-bearing factors for a variety of H&E technologies, describes a design basis for ultrasonic harvesters, and provides a framework to measure future technological advancements toward reducing H&E costs. Lastly, we show that ultrasonic harvesters and extractors are uniquely capable of meeting both NAABB and NABTR targets. Ultrasonic technologies require further development and scale-up before they can achieve low-cost performance at industrially relevant scales. However, the advancement of this technology would greatly reduce H&E costs and accelerate the commercial viability of algae-based biofuels.

Techno-economic analysis of liquid fuel production from woody biomass via hydrothermal liquefaction (HTL) and upgrading

Techno-economic analysis (TEA) was implemented to evaluate the feasibility of developing a commercial large-scale woody biomass HTL and upgrading plant. In this system, woody biomass at 2000dry metric ton/day was assumed to be converted to bio-oil via HTL and further upgraded to produce liquid fuel. Two cases were evaluated: a state-of-technology (SOT) case with HTL experimental testing results underpinning the major design basis and a goal case considering future improvements for a commercial plant with mature technologies. Process simulation and cost analysis were conducted. The annual production rate for the final hydrocarbon product was estimated to be 42.9 and 69.9million gallon gasoline-equivalent (GGE) for the SOT and goal cases, respectively. The minimum fuel selling price (MFSP) was estimated to be $4.44/GGE for the SOT case and $2.52/GGE for the goal case. For advancing from the SOT to the goal case, the assumption of reducing the organics loss to the water phase led to the largest reduction in the production cost. Alternative configuration of small scale distributed HTL plants was evaluated. Sensitivity analysis identified key factors affecting the goal case and its cost uncertainties resulting from the assumed uncertainties in selected parameters.

Development of hydrothermal liquefaction and upgrading technologies for lipid-extracted algae conversion to liquid fuels

Bench-scale tests were performed for lipid-extracted microalgae (LEA) conversion to liquid fuels via hydrothermal liquefaction (HTL) and upgrading processes. Process simulation and economic analysis for a large-scale LEA HTL and upgrading system were developed based on the best available experimental results. The system assumed an LEA feed rate of 608dry metric tons/day and that the feedstock was converted to a crude HTL bio-oil and further upgraded via hydrotreating and hydrocracking to produce liquid fuels, mainly alkanes. Performance and cost results demonstrated that HTL and upgrading is effective for converting LEA to liquid fuels. The liquid fuels annual yield was estimated to be 26.9million gallon gasoline-equivalent (GGE) and the overall energy efficiency on a higher heating value (HHV) basis was estimated to be 69.5%. The variation range of the minimum fuel selling price (MFSP) was estimated to be $2.07 to $7.11/GGE by combining the effects of selected process factors. Key factors affecting the production cost were identified to be the LEA feedstock cost, final products yields, and the upgrading equipment cost. The impact of plant scale on MFSP was also investigated.

Life cycle optimization for sustainable design and operations of hydrocarbon biorefinery via fast pyrolysis, hydrotreating and hydrocracking

This paper addresses the optimal design and operation of hydrocarbon biorefinery via fast pyrolysis, hydrotreating and hydrocracking of hybrid poplar feedstock under economic and environmental criteria. The hydrocarbon biorefinery encompasses fast pyrolysis for crude bio-oil production, upgrading of the bio-oil through hydrotreating, separation and hydrocracking of long chained hydrocarbons into gasoline and diesel range products, and steam reforming for hydrogen production. We propose a bi-criteria nonlinear programming (NLP) model that seeks to maximize the economic performance measured by the net present value (NPV) and to minimize the environmental impacts. The environmental objective is measured with the global warming potential (GWP) metric according to the life cycle assessment procedures, which covers gate-to-gate environmental impacts of the hydrocarbon biorefinery. The multiobjective NLP model simultaneously determines the production capacity, size of each process units, operational conditions, the flow rates of species and streams at each stage of the process, hydrocarbon biofuel yields, and consumption rate of feedstock, steam, electricity, and natural gas. The bi-criteria NLP model is solved with the ɛ-constraint method, and the resulting Pareto-optimal curve reveals the trade-off between the economic and environmental dimensions of the sustainable hydrocarbon biorefinery. The optimization results reveal that the unit production cost of the hydrocarbon biofuels is $2.31 per gallon of gasoline equivalent (GGE) for the maximum NPV solution and $3.67/GGE for the minimum GWP design. The corresponding greenhouse emission is 8.07kgCO2-eq/GGE.

A sulfuric acid management strategy for the production of liquid hydrocarbon fuels via catalytic conversion of biomass-derived levulinic acid

In this study, we first develop an integrated strategy for the catalytic conversion of lignocellulose into liquid fuels based on the production of levulinic acid (LA) followed by its hydrogenation to γ-valerolactone (GVL). Our integrated strategy involves a novel catalytic conversion process employing alkylphenol-based separation to extract LA from the sulfuric acid containing aqueous solution following the sulfuric acid catalyzed deconstruction of cellulose. To minimize utility consumption, we perform heat integration, while the remaining heating requirement is satisfied by the combustion of residual biomass. Hot combustion gases are also used to generate electricity, which meets the electricity requirement of the process, while the excess electricity is sold to the grid. We perform a technoeconomic analysis for the alkylphenol-based strategy and compare its economics with a previously reported strategy, in which butyl acetate was used as an extractive solvent to separate GVL from sulfuric acid following the LA hydrogenation step. With some improvements in the process configuration, the alkylphenol strategy leads to a minimum selling price (MSP) of $4.40 per gallon of gasoline equivalent (GGE) for compatible biofuel components, whereas the butyl acetate strategy leads to a MSP of $4.68 per GGE. We show that the alkylphenol strategy becomes a significantly better choice when the catalyst lifetime for the hydrogenation of LA becomes less than 6 months.