Biodiesel Biorefinery Research Articles

Integrated Approach to Spent Coffee Grounds Valorization in Biodiesel Biorefinery

With the increasing consumption of coffee beverages, an increased amount of food waste—spent coffee grounds (SCG)—is generated and disposed into landfills or combusted in incinerators. SCG are characterized as a highly polluting substance with partial toxicity due to the presence of caffeine, tannins, and polyphenols. It also contains 15% of oil on average, and its potential for biodiesel production is thus considerable. The aim of the presented work is to evaluate the possibility and technical potential of biodiesel production from the SCG oil (SCGO) by esterification and transesterification reaction. According to the characterization of the studied SCGO, this stream must be adjusted and purified to be utilized in the existing biodiesel production plant. Fatty acids (FA) represent 85.85% of the SCGO, with two dominant FAs—linoleic and palmitic acids. The necessity of removal and disposal of unsaponifiable matter, which accounts for 15% of the SCGO content, must be highlighted when producing biodiesel from the SCG. The objective of this research was the comparison of different biodiesel production processes, where a two-step transesterification process has been identified as the most successful method for biodiesel production from the SCGO with the highest ester content of 89.62% and the lowest content of unsaponifiable and unidentified matter in the final product. The novelty of the analyses is a characterization of the d unsaponifiable matter present in the SCGO, and the article highlights the importance of progression to be considered when evaluating the technical potential of the SCG biodiesel production integrated into a biorefinery. Nevertheless, the SCG biodiesel can contribute to fulfilling the mandatory share of advanced biofuel in the fuel energy mix given by national legislation and contribution to the circular economy approach of biorefineries.

An integrated sustainable biorefinery concept towards achieving zero-waste production

Biodiesel is a cleaner fuel for the transportation sector, to reduce greenhouse gases emission, and support economic development. Despite several advantages, biodiesel processing produces a significant amount of waste, mainly water and glycerol. In this study, using a circular economy approach, an integrated biodiesel biorefinery is designed and analyzed to assess whether it can lead to better economics and a zero-waste scenario. To achieve these goals, one stand-alone and three integrated scenarios were analyzed: (1) stand-alone biodiesel production; biodiesel production integrated with (2) methanol production from CO2; (3) bio-succinic acid production; and (4) methanol and bio-succinic acid production. Each scenario was evaluated based on rigorous profitability, sensitivity and environmental analysis. For each scenario, biodiesel's minimum selling price in USD/kg was 0.30, 0.39, 0.22 and 0.44 respectively. Thereby, making integration (3) and (4) the most and least profitable respectively. By sensitivity analysis, waste cooking oil price and total capital investment were the most sensitive variables. From sustainability perspective, the scenario (3) has a waste production of 0.68 kg/kg-product, in which wastewater is 0.55 kg/kg-product. Finally, to improve sustainability, two improvements were implemented: multi-effect evaporation and wastewater treatment. Through this implementation, the waste production was reduced by 81% to 0.13 kg-waste/kg-product.

Quantification of alcohols, diols and glycerol in fermentation with an instantaneous derivatization using trichloroacetyl isocyanante via liquid chromatography-massspectrometry

A sensitive LC–MS/MS method was established to quantify diols and glycerol in fermentation broth using trichloroacetyl isocyanate as instantaneous derivatization reagent for monitoring the production of 1,3-propanediol and 2,3-butanediol from the biodiesel biorefinery process. Due to the derivatization reaction was very quickly at room temperature, only 1 min was needed for the reaction process. In addition, both extraction of analytes and evaporation of water were not employed in the analytical procedure. Furthermore, the isotope of chlorine was beneficial for understanding of the secondary mass spectrum and avoiding false positive results. Therefore, much more accurate results of diols and glycerol concentration in fermentation could be obtained even at very low levels for the evaluation of microbial metabolism pathway modification.

3-Hydroxypropionaldehyde production from crude glycerol by Lactobacillus diolivorans with enhanced glycerol uptake

BackgroundIn their quest for sustainable development and effective management of greenhouse gas emissions, our societies pursue a shift away from fossil-based resources towards renewable resources. With 95% of our current transportation energy being petroleum based, the application of alternative, carbon-neutral products—among them biodiesel—is inevitable. In order to enhance the cost structure of biodiesel biorefineries, the valorization of the crude glycerol waste stream into high-value platform chemicals is of major importance.ResultsThe purpose of this study is the production of 3-hydroxypropionaldehyde (3-HPA) from biodiesel-derived crude glycerol by Lactobacillus diolivorans. Particular focus is given on overcoming potential limitations of glycerol transport into the cell, in order to use the cells’ total glycerol dehydratase capability towards the formation of 3-HPA as the main product. Recombinant overexpression of the endogenous glycerol uptake facilitating protein PduF results in a significant increase of glycerol conversion by a factor of 1.3. Concomitantly, glycerol dehydratase activity increased from initially 1.70 ± 0.03 U/mg protein to 2.23 ± 0.11 U/mg protein. With this approach, an average productivity of 4.8 g3-HPA/(gCDM h) yielding up to 35.9 g/L 3-HPA and 0.91 mol3-HPA/molGlycerol have been obtained.ConclusionLactobacillus diolivorans proves to be a valuable cell factory for the utilization of crude glycerol delivering high-value C3 chemicals like 3-HPA, 1,3-propanediol (1,3-PDO) and 3-hydroxypropionic acid (3-HP). Enhancing the glycerol influx into the cell by genetic engineering was successful paving the way towards the commercial production of 3-HPA.

Production of Bio-ethylene From Wastes of Microalgae to Biodiesel Biorefinery

This work shows the valorization of marine microalgae protein wastes (MMPW), generated from biodiesel production, by obtaining a substrate that can be metabolized for ethylene production. MMPW were hydrolyzed with H2SO4 diluted to get both sugars and amino acids. This hydrolyzate was adapted for the growth of Pseudomonas savastanoi pv. glycinea. Reducing sugars, soluble protein, elemental analysis and gross analysis allowed determining the critical carbon-to-nitrogen ratio, which are associated to maximum specific growth rate, µmax. A chemically defined medium (CDM) was designed and optimized by using the collected information from fifty-two fermentations with different glucose, glutamate, NaCl, ferrous sulphate, minerals and stirring rotational speed. It was obtained a function that relates the carbon to nitrogen ratio with µmax for ethylene production. For C/N = 1.25, ethylene production and µmax were 15 µmol ethylene per Dry Cell Weight (DCW), and 0.151 h−1, respectively. However, when the C/N ratio increased to 28, these values were 140 µmol ethylene g DCW−1 and 0.421 h−1. The methodology proposed in this work will permit to design and evaluate others substrates of raw waste biomass for the production of ethylene.

An overview of the enzyme potential in bioenergy-producing biorefineries

Biorefineries are considered as an integrative thinking that focuses on the possibility of obtaining as many added-value products as technically and economically feasible. However, in practice most biorefineries comprise only enzymatic or chemical pretreatment followed by biofuel generation. The drop in oil prices may menace the development of this young industry, as has happened before in history. This has become a fundamental reason for which the biofuel industry should not consider only biofuels production, but enzyme and non-fuel based chemicals as well. Hence, this work aims at overviewing the most important enzymes involved in biotechnological processes and to describe their role in biorefineries. Bioethanol, biogas and biodiesel biorefineries are overviewed, along with the integrated and industrial types. Finally separation and purification processes in biorefineries are discussed. © 2016 Society of Chemical Industry

Enhanced malic acid production from glycerol with high-cell density Ustilago trichophora TZ1 cultivations.

BackgroundIn order to establish a cost-efficient biodiesel biorefinery, valorization of its main by-product, crude glycerol, is imperative. Recently, Ustilago trichophora TZ1 was found to efficiently produce malic acid from glycerol. By adaptive laboratory evolution and medium optimization, titer and rate could be improved significantly.ResultsHere we report on the investigation of this strain in fed-batch bioreactors. With pH controlled at 6.5 (automatic NaOH addition), a titer of 142 ± 1 g L−1 produced at an overall rate of 0.54 ± 0.00 g L−1 h−1 was reached by optimizing the initial concentrations of ammonium and glycerol. Combining the potential of bioreactors and CaCO3 as buffer system, we were able to increase the overall production rate to 0.74 ± 0.06 g L−1 h−1 with a maximum production rate of 1.94 ± 0.32 g L−1 reaching a titer of 195 ± 15 g L−1. The initial purification strategy resulted in 90 % pure calcium malate as solid component. Notably, the fermentation is not influenced by an increased temperature of up to 37 °C, which reduces the energy required for cooling. However, direct acid production is not favored as at a lowered pH value of pH 4.5 the malic acid titer decreased to only 9 ± 1 g L−1. When using crude glycerol as substrate, only the product to substrate yield is decreased. The results are discussed in the context of valorizing glycerol with Ustilaginaceae.ConclusionsCombining these results reveals the potential of U.trichophora TZ1 to become an industrially applicable production host for malic acid from biodiesel-derived glycerol, thus making the overall biodiesel production process economically and ecologically more feasible.

Microalgae biorefinery alternatives and hazard evaluation

Biodiesel production based on microalgae and using carbon dioxide as feedstock constitutes an attractive biofuel alternative. Technology development and process optimization are necessary to minimize the overall production cost. Moreover, in the framework of process sustainability, social and environmental impacts should include process safety aspects. In this context, the objective of this work is to develop a biodiesel production process based on microalgae and the subsequent estimation of the associated risks, thus contributing to more sustainable and safe processes.The biodiesel biorefinery is optimized, taking into account alternative configurations for algae cultivation and lipid extraction. Algae cultivation options are open ponds and tubular photobioreactors. Regarding lipid extraction, dewatering and subsequent n-hexane extraction, and combined ethanol/n-hexane extraction are the studied alternatives. Numerical results showed that open ponds and n-hexane extraction provide maximum net present value. However, n-hexane consumption dramatically rises, and industrial hazards have not been considered in the optimization process. To overcome this issue, a preliminary hazard analysis is carried out to identify hazardous materials and operations. Event trees are formulated to derive the frequencies of different accident scenarios, further determining the consequences. The major consequences of accidents involve toxic releases of high quantities of n-hexane. By comparing the proposed alternatives, this work aims to highlight the need to consider not only economic but also safety and environmental objectives in the development of a biodiesel production project.

Three routes forward for biofuels: Incremental, leapfrog, and transitional

This paper examines three technology routes for lowering the carbon intensity of biofuels: (1) a leapfrog route that focuses on major technological breakthroughs in lignocellulosic pathways at new, stand-alone biorefineries; (2) an incremental route in which improvements are made to existing U.S. corn ethanol and soybean biodiesel biorefineries; and (3) a transitional route in which biotechnology firms gain experience growing, handling, or chemically converting lignocellulosic biomass in a lower-risk fashion than leapfrog biorefineries by leveraging existing capital stock. We find the incremental route is likely to involve the largest production volumes and greenhouse gas benefits until at least the mid-2020s, but transitional and leapfrog biofuels together have far greater long-term potential. We estimate that the Renewable Fuel Standard, California's Low Carbon Fuel Standard, and federal tax credits provided an incentive of roughly $1.5–2.5 per gallon of leapfrog biofuel between 2012 and 2015, but that regulatory elements in these policies mostly incentivize lower-risk incremental investments. Adjustments in policy may be necessary to bring a greater focus on transitional technologies that provide targeted learning and cost reduction opportunities for leapfrog biofuels.

Extraction and characterization of brassinosteroids from residues of the biodiesel chain

Brassinosteroids are plant hormones whose stimulating activity on plant growth and development has been fully characterised and already investigated for agricultural applications. Straw and deoiled cakes, that are main residues from crops and processing for biodiesel production, of Brassica carinata and Brassica napus var. oleifera were analyzed for their content of brassinosteroids and compared to the concentrations detected in seeds. Brassinosteroids in these extracts were quantified by both HPLC analysis and bioactivity test, and a very high residual content was found in these by-products. B. carinata showed a higher concentration of brassinosteroids than B. napus var. oleifera. A new extraction method was optimized to accelerate the process. As brassinosteroids are hydrophobic compounds, then characterised by low water-solubility, the addition of HP-β cyclodextrin as coadjuvant was tested in order to improve their bioavailability in a commercial formulation for agricultural uses. These extracts were tested for their phytostimulating activity in pot-grown annual plants (lettuce and chard) under controlled conditions in a plant growth chamber. A significant increase of biomass yield was reached with both foliar and root treatments; no significant yield increased was observed when HP-β cyclodextrin was added. Then the formulation of a commercial bio-based product to be proposed as phytostimulant for agricultural uses is possible by extraction of brassinosteroids from residues of the biodiesel chain; this co-product can improve the addition value and reduce the environmental impact of a biodiesel biorefinery converting a byproduct, coproduct or residue in a source.

Comparison of supply and demand constraints on U.S. biofuel expansion

This paper compares supply and demand constraints on the ramp-up of biofuels in the United States. Three recent supply-side developments are assessed: (1) build-out of commercial-scale cellulosic biorefineries, (2) incremental improvements to existing ethanol and biodiesel biorefineries, and (3) use of waste oils for renewable diesel and biodiesel. From a technical perspective, we estimate these developments could increase domestic biofuels production by up to 4.3, 2.3, and 1.3 billion gallons of gasoline equivalent (BGGE) by 2030, respectively. This corresponds to 3.7% of final energy in the U.S. transportation sector in 2013. On the demand side, the main technical constraints to biofuel growth involve the blend rate of ethanol with gasoline. Rapid removal of E85 and E15 vehicle and infrastructure barriers could generate room for an additional 13.0 BGGE of ethanol and 2.7 BGGE of biodiesel consumption by 2030. There is no demand constraint on drop-in biofuels. Both supply and demand constraints limit the expansion of biofuels, but demand constraints can likely be relaxed at a faster pace than supply constraints. Whether the further expansion of biofuels is socially, economically, or environmentally justifiable is not a research question examined here.

Accelerated decantation of biodiesel–glycerol mixtures: Optimization of a critical stage in biodiesel biorefinery

When making biodiesel, slow separation of glycerol; the main by-product of the transesterification reaction, could lead to longer operating times, bigger equipment and larger amount of steel and consequently increased production cost. Therefore, acceleration of glycerol/biodiesel decantation could play a significant role in economic viability of the overall biodiesel refinery process. In the present study, the interactive effects of prominent parameters i.e. temperature (25–65°C), NaCl addition (0–2g/100ml), and methanol concentrations (10–30vol.%) on decantation behavior of glycerol/biodiesel mixture were studied using Box–Behnken design matrix and response surface methodology (RSM). The findings revealed that in low temperature ranges, the main factor influencing decantation speed was density difference while at high temperature ranges, viscosity variation played the major role. Moreover, decantation time was significantly decreased by 200% (3min) at the optimum conditions achieved i.e. 45°C, 1g NaCl addition and 20% excess methanol. The methyl ester yield was measured at >90% under optimum conditions which was increased to ASTM quality (>96.5%) after washing and drying procedures.

Implementation of Heat Integration to Improve the Sustainability of an Integrated Biodiesel Biorefinery

Recently, a great research effort has been dedicated in order to establish integrated biorefineries as the next generation plants for the production of fuels, energy and chemicals. In this work, heat integration techniques are applied to an integrated biodiesel biorefinery that as well as biodiesel it also produces succinic acid through a fermentation process in order to improve its economic efficiency. Initially, heat integration options are identified by extracting the thermodynamic results of the overall biorefinery from simulations carried out in Aspen Plus 2006.5. By implementing pinch analysis and stochastic optimisation techniques, we determine a new heat exchanger network (HEN) that shows a minimum total annualised cost (TAC) of the overall HEN. The optimisation of the HEN results in a 17.2 % reduction in the TAC and 62.3 % and 64.2 % reduction in the hot and cold utilities, respectively, compared to the initial plant.

Biodiesel biorefinery: opportunities and challenges for microbial production of fuels and chemicals from glycerol waste

The considerable increase in biodiesel production worldwide in the last 5 years resulted in a stoichiometric increased coproduction of crude glycerol. As an excess of crude glycerol has been produced, its value on market was reduced and it is becoming a “waste-stream” instead of a valuable “coproduct”. The development of biorefineries, i.e. production of chemicals and power integrated with conversion processes of biomass into biofuels, has been singled out as a way to achieve economically viable production chains, valorize residues and coproducts, and reduce industrial waste disposal. In this sense, several alternatives aimed at the use of crude glycerol to produce fuels and chemicals by microbial fermentation have been evaluated. This review summarizes different strategies employed to produce biofuels and chemicals (1,3-propanediol, 2,3-butanediol, ethanol, n-butanol, organic acids, polyols and others) by microbial fermentation of glycerol. Initially, the industrial use of each chemical is briefly presented; then we systematically summarize and discuss the different strategies to produce each chemical, including selection and genetic engineering of producers, and optimization of process conditions to improve yield and productivity. Finally, the impact of the developments obtained until now are placed in perspective and opportunities and challenges for using crude glycerol to the development of biodiesel-based biorefineries are considered. In conclusion, the microbial fermentation of glycerol represents a remarkable alternative to add value to the biodiesel production chain helping the development of biorefineries, which will allow this biofuel to be more competitive.

A techno-economic analysis of biodiesel biorefineries: Assessment of integrated designs for the co-production of fuels and chemicals

In this work we explore the concept of integrated biorefineries, and we examine alternative schemes for the co-production of biofuels (biodiesel) and chemicals (succinic acid). Four different biorefinery schemes considering the different uses of crude glycerine from the biodiesel process are simulated and compared: (i) the disposal of crude glycerine as a waste, (ii) the purification (through distillation) of crude glycerine to 80%, (iii) the purification of glycerine to 95%. and (iv) the production of succinic acid from glycerine through fermentation. For the latter, we consider the bioprocess that converts the glycerol to succinate, and a downstream separation process that purifies and crystallises our product to the final succinic acid crystals. To apply complex kinetics for the fermentation we have linked Aspen Plus (2006.5) with Matlab (R2007b), where we have used the experimentally-based unstructured model from Vlysidis et al., 2009 and 2010. We first determine the operating parameters of the fermentor that have a significant effect on the economics of this scenario, i.e. the cycle time of the batch fermentation and the water flowrate entering the bioreactor. Subsequently, we perform single- and multi-objective optimisation to maximise the profit and/or to minimise the environmental impact of the overall process. We then analyse and compare the economics of the four different biorefinery schemes by using well-known profitability and/or emission criteria. Furthermore, we carry out sensitivity analysis that takes into consideration price variations for the most important materials and we extract firm conclusions about the profitability of each scenario. It is found that succinic acid co-production can enhance the profit of the overall biorefinery by 60% for a 20 years plant lifetime. These results indicate the importance of glycerol when it is utilised as a key renewable building block for the production of commodity chemicals.