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

Pacific Northwest National Laboratory, Richland, WA 99354, USA
Algal Research (Impact Factor: 5.01). 10/2013; 2(4). DOI: 10.1016/j.algal.2013.07.003

ABSTRACT 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 608 dry 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 26.9 million 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.

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    • "Valdez et al. (2014) presented a reaction network and kinetic model to describe HTL of any algae species. Some researchers investigated the performance of lipid-extracted algae under hydrothermal conditions and the reaction behavior of residual algae after extracting polysaccharides (Miao et al., 2012; Valdez et al., 2012; Zhu et al., 2013). Biller and Ross (2011) found that the bio-oil yield from a range of model biochemical components at 350 °C followed the trend lipids > proteins > carbohydrates. "
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    ABSTRACT: Crude polysaccharides and proteins extracted from algae were chosen as model materials to investigate the hydrothermal liquefaction (HTL) characteristics and pathways of low-lipid algae. Liquefaction behavior of the two individuals and their binary mixtures with different mass ratios were evaluated under different temperatures. Formation pathways of bio-oil from crude polysaccharides/proteins were proposed. Results showed that polysaccharides had a small contribution to bio-oil (<5%) and approximately 60% distributed in aqueous phase, while proteins played a crucial role on bio-oil formation (maximum 16.29%). Bio-oil from polysaccharides mainly contained cyclic ketones and phenols and from proteins composed of pyrazines, pyrroles and amines. Interaction between polysaccharides and proteins forming polycyclic nitrogenous compounds had a negative effect on bio-oil yield at 220 and 260°C. However, their further decomposition caused increase of bio-oil yield at 300°C. Mixture liquefaction obtained the highest higher heating value (HHV) of bio-oil and energy recovery than polysaccharides/proteins liquefaction at 300°C. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Bioresource Technology 07/2015; 196:99-108. DOI:10.1016/j.biortech.2015.07.020 · 4.49 Impact Factor
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    • "These objectives can broadly be divided in two categories: first for energy production by utilizing the remaining carbon and hydrogen, and secondly for extracting products for their nutritional and economical values. Zhu et al. (2013) studied the hydrothermal liquefaction potential of lipid extracted algae (LEA) for their 0960-8524/Ó 2014 Elsevier Ltd. All rights reserved. "
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    ABSTRACT: The objective of this study was to investigate the feasibility of using lipid extracted algae (LEA) as a source for protein and reduced sugar, and the effects of various procedural treatments on their yields. LEA provided comparable yields of protein and reduced sugars to those from total algae. Oven drying provided highest yields of all products followed by freeze drying, while sun drying significantly lowered their yields. Effective cell disruption by microwave and autoclave increased the lipid yields from algae, but resulted in increased loss of other compounds with lipid extracting solvents lowering their yields during sequential extraction. Relatively inefficient cell disruption by ultrasonication and osmotic shock lowered the amount of cell protein lost to the lipid extracting solvents. These results highlight the complexity of concurrent extraction of all value added products from algae, and the need for proper selection of the processes to achieve the objectives of integrated biorefinery.
    Bioresource Technology 12/2014; 179. DOI:10.1016/j.biortech.2014.12.047 · 4.49 Impact Factor
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    • "As part of NAABB, a techno-economic analysis for HTL of algal biomass was prepared based experimental results. A manuscript of the TEA was prepared and has been published (Zhu et al., 2013). The primary cost driver was determined to be the algae feedstock cost. "
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    ABSTRACT: This review describes the recent results in hydrothermal liquefaction (HTL) of biomass in continuous-flow processing systems. Although much has been published about batch reactor tests of biomass HTL, there is only limited information yet available on continuous-flow tests, which can provide a more reasonable basis for process design and scale-up for commercialization. High-moisture biomass feedstocks are the most likely to be used in HTL. These materials are described and results of their processing are discussed. Engineered systems for HTL are described; however, they are of limited size and do not yet approach a demonstration scale of operation. With the results available, process models have been developed, and mass and energy balances determined. From these models, process costs have been calculated and provide some optimism as to the commercial likelihood of the technology.
    Bioresource Technology 10/2014; 178. DOI:10.1016/j.biortech.2014.09.132 · 4.49 Impact Factor
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