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American Society for Testing and Materials

Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

Nanocellulose: Extraction and application

Insights into biochar and hydrochar production and applications: A review

Current global energy scenario and the environmental deterioration aspect motivates substituting fossil fuel with a renewable energy resource - especially transport fuel. This paper reviews the current status of trending biomass to liquid (BTL) conversion processes and focuses on the technological developments in Fischer Tropsch (FT) process. FT catalysts in use, and recent understanding of FT kinetics are explored. Liquid fuels produced via FT process from biomass derived syngas promises an attractive, clean, carbon neutral and sustainable energy source for the transportation sector. Performance of the FT process with various catalysts, operating conditions and its influence on the FT products are also presented. Experience from large scale commercial installations of FT plants, primarily utilizing coal based gasifiers, are discussed. Though biomass gasification plants exist for power generation via gas engines with power output of about 2 MWe; there are only a few equivalent sized FT plants for biomass derived syngas. This paper discusses the recent developments in conversion of biomass to liquid (BTL) transportation fuels via FT reaction and worldwide attempts to commercialize this process. All the data presented and analysed here have been consolidated from research experiences at laboratory scale as well as from industrial systems. Economic aspects of BTL are reviewed and compared. (C) 2015 Elsevier Ltd. All rights reserved.

Biomass to liquid transportation fuel via Fischer Tropsch synthesis – Technology review and current scenario

This study compared the fundamental properties of cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) extracted from sugarcane bagasse. Conventional hydrolysis was used to extract CNC while ball milling was used to extract CNF. Images generated by scanning electron microscope and transmission electron microscope showed CNC was needle-like with relatively lower aspect ratio and CNF was rope-like in structure with higher aspect ratio. Fourier-transformed infrared spectra showed that the chemical composition of nanocellulose and extracted cellulose were identical and quite different from bagasse. Dynamic light scattering studies showed that CNC had uniform particle size distribution with a median size of 148 nm while CNF had a bimodal size distribution with median size 240 ± 12 nm and 10 μm. X-ray diffraction showed that the amorphous portion was removed during hydrolysis; this resulted in an increase in the crystalline portion of CNC compared to CNF. Thermal degradation of cellulose initiated at a much lower temperature, in the case of the nanocrystals while the CNF prepared by ball milling were not affected, indicating higher thermal stability.

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A comparison of cellulose nanocrystals and cellulose nanofibres extracted from bagasse using acid and ball milling methods

Hydrothermal liquefaction (HTL) presents a viable route for converting a vast range of materials into liquid fuel, without the need for pre-drying. Currently, HTL studies produce bio-crude with properties that fall short of diesel or biodiesel standards. Upgrading bio-crude improves the physical and chemical properties to produce a fuel corresponding to diesel or biodiesel. Properties such as viscosity, density, heating value, oxygen, nitrogen and sulphur content, and chemical composition can be modified towards meeting fuel standards using strategies such as solvent extraction, distillation, hydrodeoxygenation and catalytic cracking. This article presents a review of the upgrading technologies available, and how they might be used to make HTL bio-crude into a transportation fuel that meets current fuel property standards.

https://www.mdpi.com/1996-1073/8/7/6765/pdf

A Review of Hydrothermal Liquefaction Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels

Biochar generated from thermochemical conversion of biomass reduces greenhouse gas emissions and is useful for improving ecological systems in agriculture. However, certain biochars function well in improving soil, and other biochars do not. Why? Because it is not clear how to prepare the best biochar for soil. There is a disconnect between biochar preparation and returning the biochar to the soil. To elucidate this relationship, this paper reviews (i) technologies for preparing biochar, (ii) how preparation conditions affect biochar properties, and (iii) the effects on soil physical and chemical properties. In addition to reducing greenhouse gas emissions, biochar improves the physicochemical and microbial properties of soil and absorbs poisonous and pernicious substances. Therefore, as biochar is produced by pyrolysis, optimizing processing conditions to improve its properties for agricultural use is a key issue explored in this article.

Returning biochar to fields: A review

This study presents an overview of the context and global impacts of recent International Maritime Organization (IMO) regulations on the marine fuel oil refining industry, future marine fuel mix and ship emissions. IMO limited marine fuel sulphur content in both Sulphur Emission Control Areas (SECAs) and Nitrogen Oxide Emission Control Areas (NECAs) to 0.1% (wt. %) by 2015, and to 0.5% globally by 2020. It is anticipated that the newly implemented IMO regulations will help to mitigate negative impact of ship emissions on public health and environment. IMO regulations require significant changes to refineries to increase the production of low sulphur fuels through a shift to distillates, use of novel deep desulphurization techniques, or fuel blending. Changes to the refinery processes can bring forth increases in greenhouse gas emissions and high capital investments. Alternative fuels will need to meet the required reduction of air pollutants and greenhouse gas emissions in coastal areas. Alternative marine fuels consisting of liquefied nature gas (LNG) and biofuel may be suitable fuels to meet both targets. These two fuels are predicted to account for 50% of shipping energy demand by 2050, while the remainder will still be supplied by conventional heavy fuel oil (HFO)/marine gas oil (MGO). Switching to low sulphur fuels as a results of the new IMO regulations has led to measureable reductions in ship emissions generally. This fuel switching also resulted in changes in engine emission characteristics, especially on particulate matter chemical composition.

/pdf/global-impacts-of-recent-imo-regulations-on-marine-fuel-oil-2x6is1j1qe.pdf

Thomas J. Rainey

Papers

A comparison of cellulose nanocrystals and cellulose nanofibres extracted from bagasse using acid and ball milling methods

A Review of Hydrothermal Liquefaction Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels

Returning biochar to fields: A review

Global impacts of recent IMO regulations on marine fuel oil refining processes and ship emissions

Returning biochar to fields: A review