Hydroprocessing of bio-crude from continuous hydrothermal liquefaction of microalgae

Biller, Patrick; Sharma, Brajendra K.; Kunwar, Bidhya; Ross, Andrew B.

doi:10.1016/j.fuel.2015.06.077

Cited by 234 publications

(159 citation statements)

References 36 publications

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“…Since the yield of bio-crude oil was 51%, and thus the process yielded 102 kg biocrude with a 35 MJ/kg heating value [27]. Total energy recovered in the bio-crude oil was 3,570 MJ.…”

Section: Energy Output From Htl Productsmentioning

confidence: 99%

A Comparison of Energy Consumption in Hydrothermal Liquefaction and Pyrolysis of Microalgae

Yang¹,

Wu²,

Deng³

et al. 2017

Tr Ren Energy

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The energy requirements for converting one tonne (1,000 kg) of Chlorella slurry of 20 wt% solids via fast pyrolysis, microwave-assisted pyrolysis (MAP), and hydrothermal liquefaction (HTL) were compared. Drying microalgae prior to pyrolysis by using a spray drying process with a 50% energy efficiency required an energy input of 4,107 MJ, which is higher than the energy content (4,000 MJ) of raw microalgae. The energy inputs to conduct fast pyrolysis, MAP, and HTL reactions were 504 MJ (50% efficient), 1,057 MJ (~25% efficient), and 2,776 MJ (50% efficient), respectively. The overall energy requirement of fast pyrolysis is theoretically about 1.6 times more than that of HTL. The energy recovery ratios for fast pyrolysis, MAP, and HTL of microalgae were 78.7%, 57.2%, and 89.8%, respectively. From the energy balance point of view, hydrothermal liquefaction is superior, and it achieved a higher energy recovery with a less energy cost. To improve the pyrolysis process, developing drying devices powered by renewable energies, optimizing the pyrolysis process (specifically microwave-assisted), and improving the energy efficiency of equipment are options. IntroductionThermochemical conversion of microalgae can be divided into pyrolysis of dry algae and hydrothermal liquefaction (HTL) of algal slurries [1]. Usually, the microalgal culture has a very dilute concentration of 0.1-1% dry solids. Currently, the proposed harvesting process is using a series of mechanical unit operations to dewater the microalgae media to a level of ~20% dry solids, which is considered as a less energy intensive processing option than completely drying microalgae for pyrolysis purpose. Drying is one of most dominant costs for algae harvest and may account for 30% of the total product costs, and the power consumption was equivalent to 15.8% of the energy of the recovered hydrocarbon [2]. Because of this energy consumption barrier, pyrolysis is considered as a kind of hopeless technologies for microalgae and only limited to laboratory investigations [3]. Meanwhile, researchers also recognized the advantages of the pyrolysis of microalgae (such as higher quality of pyrolytic bio-oil than that of cellulosic biomass) [4] and the merits of pyrolysis technology (such as lower capital cost than HTL) [5,6].This paper provides a simple comparison between the energy consumptions in pyrolysis of microalgae and hydrothermal liquefaction of microalgae. The purpose is not to provide a complete evaluation to these conversion technologies, but to give an idea how the energy consumption impacted the conversion processes of microalgae, and what would be the possible solutions. Methodology MicroalgaeThe composition analysis and properties of Chlorella sp. are summarized in Table 1. An engineered Chlorella sp. was assumed to be grown autotrophically, and had following components: 25% fatty acids, 50% protein, 15% polysaccharide, and 10% ash. For calculation, one tonne (1,000 kg) of Chlorella slurry at 20°C with 20 wt% solids and 80 wt% water (i.e. 200 kg dry alga...

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“…Since the yield of bio-crude oil was 51%, and thus the process yielded 102 kg biocrude with a 35 MJ/kg heating value [27]. Total energy recovered in the bio-crude oil was 3,570 MJ.…”

Section: Energy Output From Htl Productsmentioning

confidence: 99%

A Comparison of Energy Consumption in Hydrothermal Liquefaction and Pyrolysis of Microalgae

Yang¹,

Wu²,

Deng³

et al. 2017

Tr Ren Energy

View full text Add to dashboard Cite

show abstract

“…Schematic illustration of the HTL in a continuous process flow diagram of the HTL unit at the University of Sydney , .…”

Section: Methodologiesmentioning

confidence: 99%

“…In addition, optimum HTL conditions reduce the required upgrading processes . Spirulina, Chlorella, and Butyroccoccus are among the most commonly used microalgae for biocrude production through HTL , , , , . Biomass with higher lipid content results in more biocrude compared to biomasses with a higher protein and carbohydrate content .…”

Section: Microalgal Htlmentioning

confidence: 99%

Continuous Hydrothermal Liquefaction for Biofuel and Biocrude Production from Microalgal Feedstock

Lababpour¹

2018

ChemBioEng Reviews

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Microalgal biomass processing by continuous hydrothermal liquefaction (HTL) has recently received much interest and can be used to convert microalgal biomass to biocrude oil and drop‐in fuels. This review focuses on the conversion of microalgae biomass to energy production through continuous HTL processes. In addition, processes for upgrading feedstocks and biocrude are also discussed. The feed of the biomass slurry is treated according to size and moisture regulations. Following separation of the gaseous, liquid, and solid phases, the determination of elemental, physical, and chemical fragments, yield of energy, and other properties of the various products is carried out. Homogeneous or heterogeneous catalysts improve the biocrude yield and quality as does higher moisture content. The high percentage of N2 and O2 in the feedstock results in lower quality products. This may be resolved through pre‐processing of the biomass, controlling of HTL processes conditions, and post‐upgrading processing of the HTL products. The promising potential of microalgae biomass for biocrude and drop‐in fuels may have an important contribution to the world's renewable energy sources through HTL in the near future.

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“…In the future, they must adopt a method that can resolve the clogging issue, which will successfully prolong the process time [16]. Other problems, for example, nitrogen content in the oil [17], can be resolved using two-stage HTL. In two-stage HTL, Stage 1 was pre-treatment (<200 • C) and stage 2 was the main treatment (250-350 • C).…”

Section: Energy Requirementsmentioning

confidence: 99%

Microalgae Oil Production: A Downstream Approach to Energy Requirements for the Minamisoma Pilot Plant

et al. 2018

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This study investigates the potential of microalgae oil production as an alternative renewable energy source, in a pilot project located at Minamisoma City in the Fukushima Prefecture of Japan. The algal communities used in this research were the locally mixed species, which were mainly composed of Desmodesmus collected from the Minamisoma pilot project. The microalgae oil-production processes in Minamisoma consisted of three stages: cultivation, dewatering, and extraction. The estimated theoretical input-energy requirement for extracting oil was 137.25 MJ to process 50 m 3 of microalgae, which was divided into cultivation 15.40 MJ, centrifuge 13.39 MJ, drum filter 14.17 MJ, and hydrothermal liquefaction (HTL) 94.29 MJ. The energy profit ratio (EPR) was 1.41. The total energy requirement was highest in the HTL process (68%) followed by cultivation (11%) and the drum filter (10%). The EPR value increased along with the yield in the cultivation process. Using HTL, the microalgae biomass could be converted to bio-crude oil to increase the oil yield in the extraction process. Therefore, in the long run, the HTL process could help lower production costs, due to the lack of chemical additions, for extracting oil in the downstream estimation of the energy requirements for microalgae oil production.

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Hydroprocessing of bio-crude from continuous hydrothermal liquefaction of microalgae

Cited by 234 publications

References 36 publications

A Comparison of Energy Consumption in Hydrothermal Liquefaction and Pyrolysis of Microalgae

A Comparison of Energy Consumption in Hydrothermal Liquefaction and Pyrolysis of Microalgae

Continuous Hydrothermal Liquefaction for Biofuel and Biocrude Production from Microalgal Feedstock

Microalgae Oil Production: A Downstream Approach to Energy Requirements for the Minamisoma Pilot Plant

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