Biocrude Oil Production Research Articles

A comparison of bio-crude oil production from five marine microalgae – Using life cycle analysis

Marine microalgae biomass could offer a viable feedstock for sustainably producing biofuel by hydrothermal liquefaction. In this study, five promising marine microalgae (i.e., Tetraselmis, Picochlorum, Synechococcus, Chroococcidiopsis, and Dunaliella), having different characteristics, were studied for biocrude oil production. The overall microalgal biocrude oil production process was divided into six unit operations: water supply, CO2 supply, nutrient supply, cultivation, harvesting, and HTL process. Models were developed for these unit processes such that once the key parameters of any unit process are known, the corresponding energy consumption could be determined. While the selection of the cultivation site influenced the energy requirements for sourcing seawater and CO2, the characteristics of the strain influenced energy requirements for the other four-unit operations. A cradle-to-grave concept was assumed to compare the life cycle assessment of the five strains. Among these strains, Tetraselmis sp. provided the most favorable energy balance with a net energy gain of 1.77 GJ/barrel of biocrude, an energy return on investment value of 2.81, and GHG reduction potential of 129 kg CO2 equivalent/barrel of biocrude. Further investigation with sensitivity analysis confirmed that the net energy yield for Tetraselmis sp. was least affected by a ±10% variation of the parameters of the unit processes.

Enhancing faecal sludge derived biocrude quality and productivity using peat biomass through co-hydrothermal liquefaction

Faecal sludge (FS) and drained peatlands have become the hotspots research area in recent years, causing significant environmental pollution and greenhouse gas (GHGs) emissions. Hence, this study explored the co-hydrothermal liquefaction (co-HTL, 300 °C for 60 min) of peat (P) and FS at different ratios (100:0, 25:75, 50:50, 75:25, and 0:100% of P: FS) to produce high-quality biocrude as a “waste to energy” approach. A positive synergistic effect was observed in P and FS co-HTL with higher biocrude yield and enhanced quality than individual HTL. Among the co-HTL ratios, the optimum biocrude yield of 44.58% was observed for the 50-50 ratio (P50FS50) with a conversion rate of 55.8% and energy recovery of 72%. However, the highest HHV was obtained from co-HTL of P75FS25 (35.5 MJ/kg), where biocrude had higher C (70.5%) and H (10.4%) contents with less amount of N (0.01%). The elemental composition of co-HTL indicated that biocrude had potential similarities to petro-crude. FTIR analysis confirmed that biocrude samples had aliphatic hydrocarbons, phenols, and esters, where the oil quality was immature to premature grade oil of kerogen type I (highly oil-prone). GC-FID hydrocarbon fractionation analysis revealed that the optimum lighter fraction crude (35.3%) was produced from co-HTL of the P50FS50 sample. In this context, the findings demonstrated that the co-HTL of P and FS might be an alternative approach for green biocrude oil production.

Fast Hydrothermal Liquefaction Coupled with Homogeneous Catalysis to Valorize Livestock Manure for Enhanced Biocrude Oil and Hydrochar Production

Fast Hydrothermal Liquefaction Coupled with Homogeneous Catalysis to Valorize Livestock Manure for Enhanced Biocrude Oil and Hydrochar Production

Hydrothermal liquefaction of Fucus vesiculosus algae catalyzed by Hβ zeolite catalyst for Biocrude oil production

Low lipid content brown algae (Fucus vesiculosus) are considered an efficient biocrude oil source for their higher productivity rate, adaptation, and ease of cultivation. The hydrothermal liquefaction process can directly utilize algal biomass in the wet state. Hβ zeolite catalyst activity was tested for the hydrothermal liquefaction process of F. vesiculosus algal biomass. Maximum biocrude oil yield (27.6%) from the F. vesiculosus algae feedstock was obtained using catalyst amount of 15 wt%, residence time of 20 min, and temperature of 300 °C. The higher heating value (HHV) of the biocrude oil product was found to be 38.47 kJ/kg. Chemical compounds in the biocrude oil and aqueous phase products were detected using Gas Chromatography-Mass Spectroscopy (GC–MS) showing the main compounds to be ketones, and nitrogen-containing and heterocyclic compounds in biocrude oil, while oxygenated compounds prevail in the aqueous phase. Low amounts of amines and amides due to low protein content and of esters and hydrocarbons because of low lipids content were found in the F. vesiculosus algae feedstock. Biocrude oil energy efficiency was 45.68% compared to the biochar energy efficiency of 16.54%.

Hydrothermal Liquefaction of Cornstalk by Reusing Pyroligneous Acid: Synergistic Effects on Biocrude Oil Formation and Solid Residue Accumulation

The reuse of process wastewater as a reaction medium in hydrothermal liquefaction (HTL) of biomass to enhance biocrude oil (BO) production has been investigated, but the interaction between the biomass and process wastewater has rarely been studied. In the present work, pyroligneous acid (PA) was used as the reaction medium and substrate during the HTL process of cornstalk (CS). Hydrothermal conversion of PA itself, HTL of CS with water, and coliquefaction of CS and PA were carried out in a high-temperature and high-pressure batch reactor. Effects of reaction temperature and PA on the yields and characteristics of products were investigated. The PA itself was hydrothermally converted into BO, solid residue (SR), an aqueous phase, and gases. Reaction temperature had a strong influence on the product distribution during the coliquefaction of CS and PA but little influence on products during PA hydrothermal conversion. The highest BO yield from PA hydrothermal conversion occurred at 300 °C (28.96 wt %). For the coliquefaction of CS and PA, the highest experimental BO yield was 31.29 wt % at 300 °C, exceeding its corresponding theoretical value by 3.28 wt %; the experimental SR yield at 350 °C was 13.01 wt %, with the highest increase of 3.34 wt % compared to its corresponding theoretical value. The synergistic effects of CS and PA occurred at high temperatures (300 and 350 °C), promoting BO formation and strengthening SR accumulation, possibly due to the interactions among the compounds dissolved in PA and the components of CS. The BOs obtained from CS and PA coliquefaction had similar C, H, and O contents and higher heating values (HHVs) than those of HTL of CS, suggesting that the reuse of PA in HTL did not compromise the oil quality. Compared with the HTL of CS with water, CS and PA coliquefaction resulted in reduced concentrations of phenols, N-containing compounds, and organic acids and higher concentrations of ketones, alcohols, and hydrocarbons. Hence, PA clearly affected the distribution of organic components in BOs. In addition, more carbonaceous SRs were produced from coliquefaction with C and O contents of 65.14–70.23 and 23.94–29.89 wt %, respectively, and HHVs of 22.77–26.99 MJ/kg.

Bio-crude oil production and valorization of hydrochar as anode material from hydrothermal liquefaction of algae grown on brackish dairy wastewater

Hydrothermal liquefaction (HTL) is effective at recovering bioenergy from wet microalgae, which is used for cleaning polluted water body. In this study, a brackish water-grown microalgae polyculture was hydrothermally liquefied into 26.5 wt% bio-crude oil with an energy consumption ratio of 2.4, indicating an energy negative process for bioenergy production. To improve the economic feasibility of wastewater algae-to-bioenergy process, a HTL byproduct, hydrochar, has been recycled to assemble in lithium ion batteries (LIBs) as a renewable anode material. Owing to the organic components produced from HTL and high concentrations of impurities obtained from brackish water, HTL hydrochar needs to be post-treated (CO2 activation and ‘base-acid’ wash) to increase carbon content, leading to better electrochemical performance. By virtue of increased specific surface area (304.06 m2 g−1) and massive mesopores, post-treated hydrochar exhibits reversible discharge-charge capacity of 226 and 223 mAh g−1 at 0.1 A g−1 after 40 cycles. There is no related study to investigate the feasibility of brackish-grown algae-derived hydrochar as green anodes of LIBs. This integration will not only mitigate water pollution (algae treatment for brackish water), produce carbon-neutral alternative to fossil fuel (algae-derived biofuel production), but also valorize solid byproduct for generating clean energy (LIBs anodes synthesis from biomass-derived carbon).

Feasibility of Utilizing Wastewaters for Large-Scale Microalgal Cultivation and Biofuel Productions Using Hydrothermal Liquefaction Technique: A Comprehensive Review.

The two major bottlenecks faced during microalgal biofuel production are, (a) higher medium cost for algal cultivation, and (b) cost-intensive and time consuming oil extraction techniques. In an effort to address these issues in the large scale set-ups, this comprehensive review article has been systematically designed and drafted to critically analyze the recent scientific reports that demonstrate the feasibility of microalgae cultivation using wastewaters in outdoor raceway ponds in the first part of the manuscript. The second part describes the possibility of bio-crude oil production directly from wet algal biomass, bypassing the energy intensive and time consuming processes like dewatering, drying and solvents utilization for biodiesel production. It is already known that microalgal drying can alone account for ∼30% of the total production costs of algal biomass to biodiesel. Therefore, this article focuses on bio-crude oil production using the hydrothermal liquefaction (HTL) process that converts the wet microalgal biomass directly to bio-crude in a rapid time period. The main product of the process, i.e., bio-crude oil comprises of C16-C20 hydrocarbons with a reported yield of 50–65 (wt%). Besides elucidating the unique advantages of the HTL technique for the large scale biomass processing, this review article also highlights the major challenges of HTL process such as update, and purification of HTL derived bio-crude oil with special emphasis on deoxygenation, and denitrogenation problems. This state of art review article is a pragmatic analysis of several published reports related to algal crude-oil production using HTL technique and a guide towards a new approach through collaboration of industrial wastewater bioremediation with rapid one-step bio-crude oil production from chlorophycean microalgae.

Biocrude oil and high-value metabolite production potential of the Nitzschia sp.

Biocrude oil and high-value metabolite production potential of the Nitzschia sp.

Biocrude Oil Production by Integrating Microalgae Polyculture and Wastewater Treatment: Novel Proposal on the Use of Deep Water-Depth Polyculture of Mixotrophic Microalgae

Microalgae have attracted significant attention worldwide as one of the most promising feedstock fossil fuel alternatives. However, there are a few challenges for algal fuels to compete with fossil fuels that need to be addressed. Therefore, this study reviews the R&D status of microalgae-based polyculture and biocrude oil production, along with wastewater treatment. Mixotrophic algae are free to some extent from light restrictions using organic matter and have the ability to grow well even in deep water-depth cultivation. It is proposed that integrating the mixotrophic microalgae polyculture and wastewater treatment process is the most promising and harmonizing means to simultaneously increase capacities of microalgae biomass production and wastewater treatment with a low land footprint and high robustness to perturbations. A large amount of mixotrophic algae biomass is harvested, concentrated, and dewatered by combining highly efficient sedimentation through flocculation and energy efficient filtration, which reduce the carbon footprint for algae fuel production and coincide with the subsequent hydrothermal liquefaction (HTL) conversion. HTL products are obtained with a relatively low carbon footprint and separated into biocrude oil, solid, aqueous, and gas fractions. Algae biomass feedstock-based HTL conversion has a high biocrude oil yield and quality available for existing oil refineries; it also has a bioavailability of the recycled nitrogen and phosphorus from the aqueous phase of algae community HTL. The HTL biocrude oil represents higher sustainability than conventional liquid fuels and other biofuels for the combination of greenhouse gas (GHG) and energy return on investment (EROI). Deep water-depth polyculture of mixotrophic microalgae using sewage has a high potential to produce sustainable biocrude oil within the land area of existing sewage treatment plants in Japan to fulfill imported crude oil.

Integrated approach for enhanced bio-oil recovery from disposed face masks through co-hydrothermal liquefaction with Spirulina platensis grown in wastewater.

Currently, the enormous generation of contaminated disposed face masks raises many environmental concerns. The present study provides a novel route for efficient crude bio-oil production from disposed masks through co-hydrothermal liquefaction (Co-HTL) with Spirulina platensis grown in wastewater. Ultimate and proximate analysis confirmed that S. platensis contains relatively high nitrogen content (9.13%dw), which decreased by increasing the mask blend ratio. However, carbon and hydrogen contents were higher in masks (83.84 and 13.77%dw, respectively). In addition, masks showed 29.6% higher volatiles than S. platensis, which resulted in 94.2% lower ash content. Thermal decomposition of masks started at a higher temperature (≈330 °C) comparing to S. platensis (≈208 °C). The highest bio-oil yield was recorded by HTL of S. platensis and Co-HTL with 25% (w/w) masks at 300 °C, which showed insignificant differences with each other. GC/MS analysis of the bio-oil produced from HTL of algal biomass showed a high proportion of nitrogen- and oxygen-containing compounds (3.6% and 11.9%, respectively), with relatively low hydrocarbons (17.4%). Mask blend ratio at 25% reduced the nitrogen-containing compounds by 55.6% and enhanced the hydrocarbons by 43.7%. Moreover, blending of masks with S. platensis enhanced the compounds within the diesel range in favor of gasoline and heavy oil. Overall, the present study provides an innovative route for enhanced bio-oil production through mask recycling coupled with wastewater treatment.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s13399-021-01891-2.

Biocrude oil production via hydrothermal liquefaction of food waste in a simplified high-throughput reactor

In this study, the hydrothermal liquefaction of food waste was investigated for generating bio-oils or biocrudes using a simplified high-throughput reactor. Different operating conditions were parametrically tested for obtaining maximum yield of biocrudes at temperatures from 280 to 340 °C and sample-to-water mixture ratios from 1:3 to 1:7, with 30 min residence time. The biocrude yields were found to increase significantly with increasing temperature and mixture ratio. A maximum biocrude yield of approximately 40% w/w dry basis (from a total liquid product yield of over 56% w/w) and energy recovery of over 70% were obtained at 340 °C and a mixture ratio of 1:7. High heating values of the resulting biocrude and solid residue were remarkably better than those of the raw material. Fatty acids, amides, N-containing compounds, and cyclic ketones were identified to be the main components of the biocrudes using advanced GCxGC/TOF-MS.

Microwave vacuum co-pyrolysis of waste plastic and seaweeds for enhanced crude bio-oil recovery: Experimental and feasibility study towards industrialization

Waste-to-energy is a promising approach to tackle the energy shortage and reduce the environmental pollution. The present study aimed to evaluate the technical and economic feasibility of microwave vacuum co-pyrolysis of seaweeds and low-density polyethylene (LDPE). Although the three studied seaweeds namely; Ulva intestinalis, Sargassum polycystum, and Hypnea valentiae showed similar thermal weight loss profile, U. intestinalis showed the highest biomass and bio-oil yields which resulted in superior bio-oil areal productivity of 30.1 g m−2. Therefore, it was selected for co-pyrolysis with LDPE at different blend ratios. Compared to individual pyrolysis of U. intestinalis, the increase inLDPE ratio enhanced the crude bio-oil production with simultaneous reduction in bio-char yield. The experimental bio-oil yields from co-pyrolysis showed higher values than the corresponding theoretical values, confirming a synergistic effect between the two feedstocks. The bio-oil produced from co-pyrolysis at 75% LDPE blend ratio showed better characteristics compared to the individual pyrolysis. Van Krevelen plot suggested that LDPE produces hydrogen radicals during co-pyrolysis reactions, which increased the H/C ratio and reduced the O/C ratio. GC/MS analysis confirmed that the increase in LDPE stimulates hydrocarbons proportion up to 51.2% at 75% blend ratio with significant reduction in N-containing compounds, carboxylic acids, furans, aldehydes/ketones, saccharides, and phenols. The economic feasibility analysis at a feedstock feeding rate of 11.4 ton h−1 using Aspen Plus showed estimated net profit of 23.17 million US$ for a 20-years life time plant. The present study provides a potential approach for sustainable energy recovery from waste plastic/seaweeds blend using microwave vacuum co-pyrolysis.

Conversion of tobacco processing waste to biocrude oil via hydrothermal liquefaction in a multiple batch reactor.

Fossil fuels are the primary energy source of almost all societies and economies, but it is finite and scarce. The use of non-renewable fossil fuels threatens earth’s environment. At the same time, waste from agricultural and industrial activities is increasing. Most of this waste is discarded or poorly managed, causing many other environmental issues. Converting waste to energy is a promising route to address these challenges. We investigated the hydrothermal liquefaction (HTL) of high moisture content, tobacco-processing waste in a multiple batch thermal reactor to produce biocrude oil. The effects of operating conditions were studied and optimized for maximum liquid biocrude oil yield. HTL operating conditions considered were temperatures from 280 to 340 °C and residence times from 15 to 45 min for a fixed ratio of biomass to deionized water of 1:3. The reaction temperature was found to affect the yields and distribution of products significantly. The maximum yield of the liquid biocrude oil obtained was more than 52% w/w at 310 °C and 15 min. Under these conditions, almost 90% of the energy was recovered in biocrude oil and solid products. The liquid fraction was mainly composed of phenols, ketones, and nitrogenous compounds. This study provides a potential framework for eco-technologies for biomass waste-to-energy conversion with respect to converting tobacco processing residues to liquid biofuels and biochemicals.Graphic abstract

Recycle of nitrogen and phosphorus in hydrothermal liquefaction biochar from Galdieria sulphuraria to cultivate microalgae

Hydrothermal liquefaction (HTL) of G. sulphuraria (GS) has been demonstrated to produce energy-dense biocrude oil, water-soluble chemicals, and biochar. The recycling of nutrients from HTL water-soluble chemicals for algae cultivation has been demonstrated. The current study evaluated the feasibility of using HTL biochar, a by-product to recover nutrients and use the nutrients to cultivate microalgae without inhibition. GS biomass was liquefied to produce biocrude oil, biochar, water phase, and gasses under subcritical water conditions (300 °C, 15 MPa & 30 min). The N and P content in the HTL biochar were ~5.27 wt.% and ~15.98 wt.%, respectively. Both nutrients were leached from the biochar at varied pH values with ~40.23% of phosphate and ~70.01% of ammoniacal nitrogen recovery obtained at a pH of 0.5. The leached phosphates and ammoniacal nitrogen were added to N and P free Cyanidium medium (CM) for cultivating GS. Growth experiments were carried out in microtiter plates and culture tube reactors at 40 °C and with CO₂ (2–3%) supplementation. Similar growth rates were observed in cultures supplemented with the leached nutrients when compared to controls in standard CM growth media proving the absence of inhibition in the former. Comprehensive characterization of HTL biochar by Inductively Coupled Plasma Optical Emission Spectrometry, bomb calorimeter, and Scanning Electron Microscope is also presented. This study confirmed the feasibility of recovering nutrients from GS biochar and using these nutrients to cultivate algae successfully without inhibition, thus supporting reduced steps for recycling, process optimization, and HTL technology commercialization.

Anaerobic digestion of hydrothermal liquefaction wastewater from spent coffee grounds

Spent coffee grounds (SCG) are high water content lignocellulosic residues generated in large amounts by the instant coffee production industry. Recent interest in the use of SCG as biomass for biocrude oil production via hydrothermal liquefaction (HTL) pointed to the generation of an aqueous effluent rich in organic matter of high aromaticity, denominated post hydrothermal wastewater (PHWW). The anaerobic digestion of PHWW was investigated as a treatment option and was evaluated for its energy recovery potential through methane production. Sequencing batch reactors were subjected to increasing initial chemical oxygen demand (COD) levels from 1000 mg COD L−1 to 8000 mg COD L−1, to allow for gradual biomass adaptation to the substrate recalcitrance and toxicity. The highest COD removal rate was observed for an initial COD level of 4000 mg COD L−1. Under this condition, the average methane yield was 187 ± 13 mLCH4 g−1 CODadded, with average COD and total phenols removal efficiencies of 60 ± 1% and 48 ± 4%, respectively. A kinetic evaluation revealed that the methane yield decreased sharply for initial phenolic compounds concentrations above 900 mg GAE L−1. Methane production represented a 22.8% increase in the energy recovered from SCG.

Production, Utilization and Commercialization of Algae-based Bio-crude Oil

Production, Utilization and Commercialization of Algae-based Bio-crude Oil

Hydrothermal liquefaction of municipal wastewater sludge and nutrient recovery from the aqueous phase

The hydrothermal liquefaction of municipal sludge was investigated under isothermal conditions (255 °C, 45 min) with TiO2 as a catalyst. In this study, we used two separation methods (an organic solvent-assisted extraction method and the Soxhlet extraction method) for the production of bio-crude oil. The maximum yield of bio-crude oil was 20.7 wt. % reported with the Soxhlet extraction method. The aqueous phase was examined for TN, TP, COD, and TOC to determine the suitability of this phase for microalgae cultivation. Four strains of oleaginous microalgae were cultivated in the aqueous phase. The results show that the growth of microalgae in the aqueous phase was lower compared to the control medium; this may be due to the high COD value. Microalgae and yeast co-cultivation increases biomass and lipid productivity using nutrients in the aqueous phase.

Biocrude Oil from Algal Bloom Microalgae: A Novel Integration of Biological and Thermochemical Techniques.

Algal bloom microalgae are abundant in polluted water systems, but their biocrude oil production potential via hydrothermal liquefaction (HTL) is limited. This study proposed a novel process that combined biological (dark fermentation) and thermochemical (HTL) techniques aimed at changing the feedstock characteristics to be more suitable for thermochemical conversion, herein named integrated dark fermentation-hydrothermal liquefaction (DF-HTL). DF-HTL conversion of algae significantly enhanced the biocrude oil yield (wt %), carbon content (mol), energy content (MJ), and energy conversion ratios by 9.8, 29.7, 40.0, and 61.0%, respectively, in comparison to the control. Furthermore, DF-HTL processing significantly decreased the aqueous byproduct yield (wt %), carbon content (mol), nitrogen content (mol), and ammonia content (mol) by 19.0, 38.4, 25.0, and 13.2%, respectively, in comparison to the control. Therefore, DF-HTL reduced the environmental impact associated with disposing of the wastewater byproduct. However, DF-HTL also augmented the nitrogen content (mol) of the biocrude oil by 42.2% in comparison to the control. The benefits of DF-HTL were attributed to the increased acid content, the incorporation of H2 as a processing gas, and the enhancement of the Maillard reaction, which shifted the distribution of reaction products from the aqueous phase to the biocrude oil phase. This article provides insights into the efficacy of a novel integrated biological-thermochemical processing method with distinct environmental and energetic advantages over conventional HTL that heightens the biocrude oil yield for feedstocks with a high carbohydrate and a high protein content.

Simulation of the Fast Pyrolysis of Coffee Ground in a Tilted-Slide Reactor

The fast pyrolysis of coffee ground for bio-crude oil production was simulated in a tilted-slide reactor. The biochemical composition was derived by an extended biomass characterization method based on the elemental analysis. The simulation was performed in a steady-state and a Lagrangian multiphase model was adopted to describe the transport of sand and biomass particles together with a multistep kinetic mechanism for fast pyrolysis. When the secondary tar cracking reactions were not considered the volatile yield increased monotonically with temperature. The inclusion of secondary reactions could improve the prediction of volatile yield which turn to decrease at higher temperature. It was found that not only the maximum volatile yield but also the corresponding reactor temperature agreed well with the experimental results. At the temperature higher than 550 °C the trend of volatile yield is similar to that of experiment while it is larger at lower reactor temperature. The individual species yields were compared at various reactor temperatures and the pyrolysis processes were analyzed by tracking the reference components when they were decomposed along the distance. It was found that the reactor temperature should be above 500 °C for effective pyrolysis of all reference components of coffee ground.

Biocrude oil and hydrochar production and characterization obtained from hydrothermal liquefaction of microalgae in methanol-water system

Hydrothermal liquefaction of microalgae under milder reaction conditions was studied for the production and characterization of high quality biocrude oil and hydrochar confirming its feasibility as sustainable biofuel source. The present study investigates the effects of solvents, temperature and time on the yield of biocrude oil. The comparatively higher yield of biocrude oil (47 wt%) obtained in methanol-water mass ratio of 0.75:0.25 also contained higher amount of ester components resulting in higher biocrude oil quality. Methanol-water co-solvent favored higher biocrude oil yield with lower nitrogen and oxygen contents as compared to pure water. Response surface methodology was applied to study the effects of temperature (222–322 °C), and reaction time (10–60min) at constant pressure of 11.5 MPa for methanol-water and biomass-solvent ratios of 0.75:0.25 and 1:5, respectively. The optimum yield of biocrude oil (57.8 wt%) and highest energy recovery (85.3%) was obtained with 75 wt% of methanol in water at 272 °C and reaction time of 35 min. Subcritical condition (temperature of 222 °C, pressure of 11.5 MPa) resulted in the highest hydrochar yield (19.5 wt%). Hydrochars were also characterized by CHNS, BET, FT-IR and TGA techniques to ascertain their prospective elemental composition, textural properties, functional groups as well as thermal stability.