A review of production and upgrading of algal bio-oil

Saber, Mohammad; Nakhshiniev, Bakhtiyor; Yoshikawa, Kunio

doi:10.1016/j.rser.2015.12.342

Cited by 257 publications

(88 citation statements)

References 170 publications

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“…The HTL process yielded 4 wt% gases, 51 wt% bio-crude oil, and 43 wt% aqueous organics and ash [5]. The non-condensable gases had following composition: 42 vol% CO2, 50 vol% NH3, 7 vol% CH4, and 1 vol% ethane [18].…”

Section: Figure 1 Naturally Dried Microalgae (A) and Ground Microalgmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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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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Section: Figure 1 Naturally Dried Microalgae (A) and Ground Microalgmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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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 cracking and aromatization reactions are usually catalyzed by Brønsted acid sites of zeolites [73,74]. Zeolites contain acid sites, and have high surface area and adsorption capacity [75]. However, some zeolite based catalysts are plagued by catalyst deactivation, short lifetime, and product contamination.…”

Section: Introductionmentioning

confidence: 99%

“…Table 6 shows the recent progresses in hydroprocessing of vegetable oil to produce hydrocarbon biofuel. Hydrogenation and other reactions crack complicated organic molecules to simpler molecules during the hydroprocessing process [75]. The typical reaction temperature for hydroprocessing of vegetable oil was between 300 °C and 390 °C.…”

Section: Introductionmentioning

confidence: 99%

Review of Heterogeneous Catalysts for Catalytically Upgrading Vegetable Oils into Hydrocarbon Biofuels

et al. 2017

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Abstract:To address the issues of greenhouse gas emissions associated with fossil fuels, vegetable oilseeds, especially non-food oilseeds, are used as an alternative fuel resource. Vegetable oil derived from these oilseeds can be upgraded into hydrocarbon biofuel. Catalytic cracking and hydroprocessing are two of the most promising pathways for converting vegetable oil to hydrocarbon biofuel. Heterogeneous catalysts play a critical role in those processes. The present review summarizes current progresses and remaining challenges of vegetable oil upgrading to biofuel. The catalyst properties, applications, deactivation, and regeneration are reviewed. A comparison of catalysts used in vegetable oil and bio-oil upgrading is also carried out. Some suggestions for heterogeneous catalysts applied in vegetable oil upgrading to improve the yield and quality of hydrocarbon biofuel are provided for further research in the future.

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Biomass Energy Systems

2017

Operation and Control of Renewable Energy Systems

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A review of production and upgrading of algal bio-oil

Cited by 257 publications

References 170 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

Review of Heterogeneous Catalysts for Catalytically Upgrading Vegetable Oils into Hydrocarbon Biofuels

Biomass Energy Systems

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