Biofuel Production Process Research Articles

Sulphur responsiveness of the Chlamydomonas reinhardtii LHCBM9 promoter.

A 44-base-pair region in the Chlamydomonas reinhardtii LHCBM9 promoter is essential for sulphur responsiveness. The photosynthetic light-harvesting complex (LHC) proteins play essential roles both in light capture, the first step of photosynthesis, and in photoprotective mechanisms. In contrast to the other LHC proteins and the majority of photosynthesis proteins, the Chlamydomonas reinhardtii photosystem II-associated LHC protein, LHCBM9, was recently reported to be up-regulated under sulphur deprivation conditions, which also induce hydrogen production. Here, we examined the sulphur responsiveness of the LHCBM9 gene at the transcriptional level, through promoter deletion analysis. The LHCBM9 promoter was found to be responsive to sulphur deprivation, with a 44-base-pair region between nucleotide positions -136 and -180 relative to the translation start site identified as essential for this response. Anaerobiosis was found to enhance promoter activity under sulphur deprivation conditions, however, alone was unable to induce promoter activity. The study of LHCBM9 is of biological and biotechnological importance, as its expression is linked to photobiological hydrogen production, theoretically the most efficient process for biofuel production, while the simplicity of using an S-deprivation trigger enables the development of a novel C. reinhardtii-inducible promoter system based on LHCBM9.

Technical analysis of crop residue biomass energy in an agricultural region of Ghana

The aim of this study was to assess crop residue biomass potential for second generation biofuel production in the Lawra–Nandom district of Ghana. The methods used in this study included interviews, survey, field and laboratory experiments. The findings show that total annual crop residues production in the Lawra–Nandom district amounts to about 272,000t. Among the major crops grown in the district, sorghum crop generates the largest quantity of residues, contributing 59% by weight of the total residues. Ethanol production potential could reach 40 million litres if 40% of the average residue generated between 2003 and 2012 were used for energy purposes. The net energy balance of the biofuel production process was 1718.7MJ with a ratio of energy output to input being 1.31. Second generations biofuels are expensive compared to first generation and research efforts aimed at technology improvement and cost reduction must intensify in order to make the technology attractive to developing countries.

Continuous production of palm biofuel under supercritical ethyl acetate

The interesterification of palm oil in supercritical ethyl acetate (ETA) to produce fatty acid ethyl ester (FAEEs) or biofuel was conducted in a continuous tubular reactor. The density of the mixtures in the system was estimated using the Peng–Robinson equation of state process simulator, and the residence time was calculated. The effects of the reaction conditions, including the molar ratios of palm oil to ethyl acetate, the temperature, and the pressure, were investigated under various mass flow rates of the mixtures and optimized. The results showed that reaction temperatures above 653K and long residence times affected the content of FAEEs and triacetin, a valuable by-product. The addition of water to the mixture in a 1:30:10M ratio of palm oil to ethyl acetate to water at 653K, 16MPa, and a mixture mass flow rate of 1.5g/min increased the total production of FAEEs and triacetin from 90.9 to 101.5wt% in 42.4min. The main finding of the present study is that triglyceride associated with ETA hydrolysis used to form acetic acid protected the products from decomposition at high temperatures and long residence times. The results will aid the selection of an efficient and economical process for alternative biofuel production from palm oil in supercritical ETA.

First developments towards closing the nutrient cycle in a biofuel production process

Hydrothermal liquefaction (HTL) of microalgae is a promising technology offering production of biofuels in a sustainable way. Thanks to the supercritical conditions applied, the recycling of water and nutrients including carbon capture becomes feasible1–2. Through HTL, the target bio-oil is generated together with process water containing valuable nutrients. In this study we have provided an environmentally friendly and resource efficient strategy to produce renewable microalgae biomass. Feasibility test on microalgae cultivation, using the nutrient-rich effluent from the HTL of same algal biomass, was performed in a 5L, flat panel airlift (FPA)–photobioreactor (PBR). 1g(DW) L−1d−1 of microalgae was the productivity average achieved with the diluted aqueous solution (25-fold). This is comparable to the productivity obtained with the standard growth medium even if an adaptation time of four days was necessary. Our results show that the nutrient rich HTL aqueous product of microalgal biomass conversion can replace to a great extent mineral salts of the culture medium. Together with an efficient water management, the nutrient recovery applied here promotes the recycling and prevents the release of waste materials and therefore shows the potential for driving the system towards a nutrient neutral production of biomass for biofuels.

Hydro‐conversion of oleic acid in bio‐oil to liquid hydrocarbons: an experimental and modeling investigation

AbstractBACKGROUNDThis study focused on understanding the reaction kinetics for the hydrocracking process. Oleic acid, as the main component of most bio‐oils, was selected as feedstock for the hydrocracking process. The hydrocracking of oleic acid was performed in a laboratory scale trickle‐bed reactor in the presence of a Ni–Zeolite β catalyst and hydrogen for hydrogenation. The concentrations of oleic acid and the three main components of jet fuel range hydrocarbons produced, which are nonane, decane and dodecane (C9, C10 and C12), were measured with GC analysis.RESULTSAccording to the aforementioned component concentrations, the rate of reaction and the related Arrhenius equation parameters were estimated. The reaction kinetic calculations were subjected to hydrocracking reactor modeling to gain a better understanding of hydrocracking. The concentrations of C9, C10 and C12 were assumed to be a separate lump of the hydrocarbons produced, namely middle hydrocarbon (MC). The reactant and MC lump concentrations throughout the reactor were measured and compared with experimental data. The modeling and experimental results are in reasonable agreement in terms of MC lump production and oleic acid conversion. The oleic acid and MC concentration profiles and reactor wall temperature profiles along the reactor were examined in this research.CONCLUSIONThe outcome of this study can be applied in simulation and commercialisation of hydrocracking as a potential process for biofuel production. © 2014 Society of Chemical Industry

Sustaining ethanol production from lime pretreated water hyacinth biomass using mono and co-cultures of isolated fungal strains with Pichia stipitis

Background: The high rate of propagation and easy availability of water hyacinth has made it a renewable carbon source for biofuel production. The present study was undertaken to screen the feasibility of using water hyacinth's hemicelluloses as a substrate for alcohol production by microbial fermentation using mono and co-cultures of Trichoderma reesei and Fusarium oxysporum with Pichia stipitis. Results: In separate hydrolysis and fermentation (SHF), the alkali pretreated water hyacinth biomass was saccharified by crude fungal enzymes of T. reesei, F. oxysporum and then fermented by P. stipitis. In simultaneous saccharification and fermentation (SSF), the saccharification and fermentation was carried out simultaneously at optimized conditions using mono and co-cultures of selected fungal strains. Finally, the ethanol production kinetics were analyzed by appropriate methods. The higher crystalline index (66.7%) and the Fourier transform infrared (FTIR) spectra showed that the lime pretreatment possibly increased the availability of cellulose and hemicelluloses for enzymatic conversion. In SSF, the co-culture fermentation using T. reesei and P. stipitis was found to be promising with a higher yield of ethanol (0.411 g g �1 ) at 60 h. The additional yield comparable with the monocultures was due to the xylanolytic activity of P. stipitis which ferments pentose sugars into ethanol. In SHF, the pretreatment followed by crude enzymatic hydrolysis and fermentation resulted in a significantly lesser yield of ethanol (0.344 g g �1 )a t 96 h. Conclusions: It is evident from the study that the higher ethanol production was attained in a shorter period in the co-culture system containing T. reesei and the xylose fermenting yeast P. stipitis. SSF of pretreated water hyacinth biomass (WHB) with P. stipitis instead of traditional yeast is found to be an effective biofuel production process.

Emergy evaluation of biofuels production in Thailand from different feedstocks

Energy demand in Thailand has steadily increased over the years. The aim of this study is thus to investigate whether the use of biodiesel, as an alternative transportation fuel, can provide a sustainable solution for future energy supply in Thailand. Seven different production cases have been classified in two main groups, three actual systems and four proposed systems. These were then investigated using emergy analysis. In the actual cases, the emergy indices indicated that case study B (biodiesel production from palm oil in industrial scale) gave the highest sustainability with emergy yield ratio (EYR), environmental loading ratio (ELR) and emergy sustainability index (ESI) recorded at 1.19, 5.18 and 0.23, respectively. Moreover, industrial scale biodiesel production appeared to be more practical in real-world operation when considering production yields. In the simulated cases, Case G (biofuels production process with steam and electricity generation zones), which utilized all waste residues to produce power and heat, was the best case with results for EYR, ELR and ESI of 1.17, 4.89 and 0.24. The best case in this study can slightly improve the emergy sustainability index. The system sustainability is still insufficient since a high portion of imported and non-renewable sources have been consumed. In pursuing sustainable development, current biomass production and biofuels conversion technologies should be improved to minimize energy and raw materials consumption. Then, the biodiesel from biomass can be considered as a suitable sustainable alternative fuel.

Discrimination of the type of biodiesel/diesel blend (B5) using mid-infrared spectroscopy and PLS-DA

The objective of this work was to differentiate the type of biodiesel in mixtures with diesel in the ratio of 5% (v/v) in relation to the type of oil and alcohol used in the production process of the respective biofuel. For this purpose, the mid-infrared (MIR) spectroscopy combined with supervised chemometric tool, partial least squares discriminant analysis (PLS-DA) was used. The distinction between six types of biodiesel/diesel blend was evaluated, in other words, Soybean Oil Ethyl Esters (SOEE), Jatropha Oil Methyl Esters (JOME), Used Frying Oil Methyl Esters (UFOME), Soybean Oil Methyl Esters (SOME), Used Frying Oil Ethyl Esters (UFOEE) and Jatropha Oil Ethyl Esters (JOEE). The PLS-DA models, showed excellent efficiency in the classification for each type of biodiesel, both in relation to type of oil as well as alcohol used in its production, with high levels of sensitivity and specificity for all classes, remitting to 100% correct classification. Therefore, the use of this methodology is a viable alternative to quality control of biodiesel because it allows identify the type of biodiesel present in biodiesel/diesel blend.

Algae-based biofuel production as part of an industrial cluster

This paper presents a study on the production of biofuels from algae cultivated in municipal wastewater in Gothenburg, Sweden. A possible biorefinery concept is studied based on two cases; Case A) combined biodiesel and biogas production, and Case B) only biogas production. The cases are compared in terms of product outputs and impact on global CO2 emissions mitigation. The area efficiency of the algae-based biofuels is also compared with other biofuel production routes. The study investigates the collaboration between an algae cultivation, biofuel production processes, a wastewater treatment plant and an industrial cluster for the purpose of utilizing material flows and industrial excess heat between the actors. This collaboration provides the opportunity to reduce the CO2 emissions from the process compared to a stand-alone operation. The results show that Case A is advantageous to Case B with respect to all studied factors. It is found that the algae-based biofuel production routes investigated in this study has higher area efficiency than other biofuel production routes. The amount of algae-based biofuel possible to produce corresponds to 31 MWfuel for Case A and 26 MWfuel in Case B.

Chitosan-graft-polydiallyldimethyl ammonium chloride for microalgae harvesting from wastewater

Harvesting microalgae is considered as a bottleneck to the process of microalgal biofuel production. Coagulation and flocculation of microalgae is shown to be the most suitable method of large-scale harvesting of microalgae. This study focused on synthesizing chitosan-g-polyDADMAC by grafting polydiallyldimethyl ammonium chloride onto the chitosan molecule to remove microalgae and total phosphorus (TP) from wastewater. Chitosan-g-polyDADMAC showed higher positive zeta potential than chitosan at all values of pH tested. Chitosan-g-polyDADMAC exhibited no isoelectric point characteristic of unmodified chitosan. Flocculant to algae mass ratio of 1:1 was required for chitosan-g-polyDADMAC to achieve 70% total suspended solids removal whereas, chitosan was required in the ratio 2:1 for 50% suspended solids removal. TP removal of nearly 20–25% was achieved with chitosan and chitosan-g-polyDADMAC at flocculant to algae ratio of 3:1. The use of chitosan-g-polyDADMAC as compared with unmodified chitosan has the potential to reduce material costs of microalgae harvesting.

Influence of high gravity process conditions on the environmental impact of ethanol production from wheat straw

Biofuel production processes at high gravity are currently under development. Most of these processes however use sugars or first generation feedstocks as substrate. This paper presents the results of a life cycle assessment (LCA) of the production of bio-ethanol at high gravity conditions from a second generation feedstock, namely, wheat straw. The LCA used lab results of a set of 36 process configurations in which dry matter content, enzyme preparation and loading, and process strategy were varied. The LCA results show that higher dry matter content leads to a higher environmental impact of the ethanol production, but this can be compensated by reducing the impact of enzyme production and use, and by polyethylene glycol addition at high dry matter content. The results also show that the renewable and non-renewable energy use resulting from the different process configurations ultimately determine their environmental impact.

Evaluation of the simultaneous production of lutein and lipids using a vertical alveolar panel bioreactor for three Chlorella species

The concept of a biorefinery improves the economic efficiency of a biofuel production process from microalgae by recovering high value added compounds. Lutein is a carotenoid currently extracted from petals of Tagetes erecta with an established market in poultry and in human nutritional supplements. For the very first time, an extended study on the lipid and lutein production over three Chlorella species as well as cell disruption methods was performed. Chlorella vulgaris, Chlorella zofingiensis and Chlorella protothecoides were grown in an indoor vertical alveolar panel photobioreactor with continuous illumination, and two cell disruption methods were assessed at a laboratory scale: glass bead vortexing and ball mill grinding. For C. vulgaris, C. zofingiensis and C. protothecoides the intracellular lutein content was measured as: 3.86, 4.38 and 3.59mgg−1 respectively. Lipid contents vary slightly among microalgae with a value close to 9% w/w. Biomass and lutein productivities were found to be higher for C. vulgaris (0.131gL−1d−1, 0.51mgL−1d−1) and for C. zofingiensis (0.122gL−1d−1, 0.53mgL−1d−1) compared to C. protothecoides (0.103gL−1d−1, 0.37mgL−1d−1).C. vulgaris 1803 and C. zofingiensis B 32 were found to be promising organisms for simultaneous production of lutein and lipids. Although all the microalgae under study belong to the same genus, a species-specific response was observed for each of the cell grinding methods tested.

Life cycle assessment of macroalgae cultivation and processing for biofuel production

There has been a recent resurgence in research investigating bioenergy production from algal biomass due to the potential environmental benefits in comparison to conventional bioenergy crops and conventional fossil fuels. This life cycle assessment (LCA) considered the energy return and environmental impacts of the cultivation and processing of macroalgae (seaweed) to bioethanol and biogas with a particular focus on specific species (Gracilaria chilensis and Macrocystis pyrifera) and cultivation methods (bottom planting and long-line cultivation). The study was based mainly upon data obtained from research conducted in Chile but the results can be applied to other locations where similar cultivation is feasible. Speculative data were also included to test promising data obtained from research. The results suggested that using base case conditions the production of both bioethanol and biogas from bottom planted Gracilaria chilensis was the most sustainable option due to the low input method of cultivation. Using new advances in cultivation and processing methods of long-line cultivated Macrocystis pyrifera however resulted in a much more sustainable source of bioenergy. If these methods can be proven on a large scale, the generation of bioenergy from macroalgae could be highly competitive in terms of its sustainability compared to alternative feedstocks. Future research should bear in mind that the results of this study should however be considered highly optimistic given the early stage of research.

Exploring the potential of microalgae for bioenergy production

Initially flocculation with chitosan to harvest algal biomass of the green alga Chlorella sorokinianawas explored. Chitosan proved to be highly efficient in the induction of flocculation with the clarification efficiency reaching >99% below pH 7 at optimal dosage. Influencing factors of flocculation efficiency and its effect on the subsequent dewatering process were also evaluated.It was shown to reduce the volume to be processed by 20–50 folds, and significantlyreduce energy input and material costs of centrifugation or filtration operations.In order to reduce the complicated and costly downstream processes of algal biofuel production, this work explores an alternative way of utilizing energy from algal cells by blending algal slurry into fossil diesel using specific combinations of surfactants. We will show that this approach provides benefits by reducing the consumption of fossil fuel; improving the engine combustion performance; and reducing exhaust emissions particularly NOx thus benefiting the environment.

Life cycle analysis of biochemical cellulosic ethanol under multiple scenarios

AbstractCellulosic ethanol is widely believed to offer substantial environmental advantages over petroleum fuels and grain‐based ethanol, particularly in reducing greenhouse gas emissions from transportation. The environmental impacts of biofuels are largely caused by precombustion activities, feedstock production and conversion facility operations. Life cycle analysis (LCA) is required to understand these impacts. This article describes a field‐to‐blending terminal LCA of cellulosic ethanol produced by biochemical conversion (hydrolysis and fermentation) using corn stover or switchgrass as feedstock. This LCA develops unique models for most elements of the biofuel production process and assigns environmental impact to different phases of production. More than 30 scenarios are evaluated, reflecting a range of feedstock, technology and scale options for near‐term and future facilities. Cellulosic ethanol, as modeled here, has the potential to significantly reduce greenhouse gas (GHG) emissions compared to petroleum‐based liquid transportation fuels, though substantial uncertainty exists. Most of the conservative scenarios estimate GHG emissions of approximately 45–60 g carbon dioxide equivalent per MJ of delivered fuel (g CO2e MJ−1) without credit for coproducts, and 20–30 g CO2e MJ−1 when coproducts are considered. Under most scenarios, feedstock production, grinding and transport dominate the total GHG footprint. The most optimistic scenarios include sequestration of carbon in soil and have GHG emissions below zero g CO2e MJ−1, while the most pessimistic have life‐cycle GHG emissions higher than petroleum gasoline. Soil carbon changes are the greatest source of uncertainty, dominating all other sources of GHG emissions at the upper bound of their uncertainty. Many LCAs of biofuels are narrowly constrained to GHG emissions and energy; however, these narrow assessments may miss important environmental impacts. To ensure a more holistic assessment of environmental performance, a complete life cycle inventory, with over 1100 tracked material and energy flows for each scenario is provided in the online supplementary material for this article.

Autohydrolysis and alkaline pretreatment effect on Chlorella vulgaris and Scenedesmus sp. methane production

Among biofuel production processes using microalgae biomass, biogas generation seems to be the least complex. Nevertheless, its efficiency is hampered due to the hard cell wall. In order to enhance its anaerobic biodegradability, the present investigation evaluated the effect of two pretreatments (low temperature autohydrolysis at 50 °C for 24 and 48 h incubation and alkaline (0.5, 2 and 5% w/w NaOH dosages)) on Chlorella vulgaris and Scenedesmus sp. The autohydrolysis resulted in 16 and 6% chemical oxygen demand (COD) solubilisation for Chlorella and Scenedesmus, respectively. During thermoalkaline pretreatment, COD in soluble phase (CODsol) was increased up to 19% for Chlorella and 17% for Scenedesmus sp. The highest carbohydrates solubilisation corresponded to 2 and 5% w/w NaOH dosage for 48 h at 50 °C for Chlorella (20%) and Scenedesmus (40–43%). When compared to Chlorella, Scenedesmus biomass exhibited higher carbohydrates solubilisation, although methane yield enhancement was low for both substrates. Best case scenario for Scenedesmus sp. (20% increase) was attained with 5% NaOH at 50 °C for 24 h. Despite the lower carbohydrates solubilisation observed for Chlorella, similar methane yields were similar to Scenedesmus sp. The low methane production enhancement was ascribed to the fact that the organic matter solubilised were exopolymers released during pretreatments rather than intracellular material.

Time reducing process for biofuel production from non edible oil assisted by ultrasonication

Limited resources of conventional fuels such as petrodiesel have led to the search for alternative fuels. Various convention batch/continuous processes for the biodiesel production have been developed before the recent year. All processes are time consuming with high labor cost. Thus, we need a new process for biodiesel production which reduces the reaction time and production cost as well as save the energy. In this work, ultrasonic assisted transesterification of Jatrophacurcas oil is carried out in the presence of methanol and potassium hydroxide (KOH) as catalyst, keeping the molar ratio of oil to alcohol 1:5, catalyst concentration 0.75wt% of oil, ultrasonic amplitude 50% and pulse 0.3 cycle, 7min reaction time under atmospheric condition. Ultrasonic mixing has increased the rate of transesterification reaction as compare to the mechanical mixing.

Comparison of energy efficiency assessment methods: Case Bio-SNG process

The goal of biofuel production is to partially replace fossil fuels in energy generation and transport. For the evaluation of biofuel production processes different criteria are applied and usually they include costs, efficiency aspects and emissions. However, evaluation of the energy efficiency of biofuels production is difficult since no general standard method exists for that. This paper compares three different assessment methods of energy efficiency both qualitatively and quantitatively. The methods are: thermal efficiency, exergy analysis and primary energy analysis. The feasibility of the methods is tested on a Bio-SNG (synthetic natural gas) production process which was modelled in AspenPlus and MS Excel. The results show that the exergy analysis seems to be advantageous when it comes to detailed (sub-) process analysis whereas the primary energy analysis offers the advantage of showing how the system is influencing the global primary energy resources. The results obtained by the thermal efficiency analysis do not add any new information to the results obtained by exergy and primary energy analyses. Exergy and primary energy analyses should be the preferred means for process assessment. Especially a combination of the two methods could offer the chance to develop a more holistic energy efficiency indicator.

The Dermal Layer of Sweet Sorghum (Sorghum bicolor) Stalk, a Byproduct of Biofuel Production and Source of Unique 3-Deoxyanthocyanidins, Has More Antiproliferative and Proapoptotic Activity than the Pith in p53 Variants of HCT116 and Colon Cancer Stem Cells

There is a growing interest in the utilization of sweet sorghum as a renewable resource for biofuels. During the biofuel production process, large quantities of biomass are generated, creating a rich source of bioactive compounds. However, knowledge of sweet sorghum stalk is lacking. We measured the phenolic content (Folin-Ciocalteu assay), antioxidant activity (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) assay), and phytochemical composition (LC-MS) in both the pith and dermal layer of the stalk. We further tested the antiproliferative (5-bromo-2'- deoxyuridine assay) and proapoptotic (terminal deoxynucleotidyl transferase dUTP nick end labeling assay) activities of these extracts using HCT116 cells and colon cancer stem cells (CCSCs) with and without the tumor suppressor gene p53. For the first time, we show that the dermal layer extract of sweet sorghum contains more of the 3-deoxyanthocyanidins apigeninidin and luteolinidin than the pith, and this is associated with more anticancer activity. Furthermore, luteolinidin suppressed CCSC proliferation more than apigeninidin. In addition to being renewable biofuel, sweet sorghum may also serve as a source of health-promoting compounds.

Oleaginous fungal lipid fermentation on combined acid- and alkali-pretreated corn stover hydrolysate for advanced biofuel production.

A combined hydrolysis process, which first mixed dilute acid- and alkali-pretreated corn stover at a 1:1 (w/w) ratio, directly followed by enzymatic saccharification without pH adjustment, has been developed in this study in order to minimize the need of neutralization, detoxification, and washing during the process of lignocellulosic biofuel production. The oleaginous fungus Mortierella isabellina was selected and applied to the combined hydrolysate as well as a synthetic medium to compare fungal lipid accumulation and biodiesel production in both shake flask and 7.5L fermentor. Fungal cultivation on combined hydrolysate exhibited comparable cell mass and lipid yield with those from synthetic medium, indicating that the integration of combined hydrolysis with oleaginous fungal lipid fermentation has great potential to improve performance of advanced lignocellulosic biofuel production.