A review of biodiesel production from microalgae

As the search for alternatives to fossil fuels continues, microalgae have emerged as a promising renewable feedstock for biodiesel. Many species contain high lipid concentrations and require simple cultivation—including reduced freshwater and land area needs—compared to traditional crops used for biofuels. Recently, technological advancements have brought microalgae biodiesel closer to becoming economically feasible through increased efficiency of the cultivation, harvesting, pretreatment, lipid extraction, and transesterification subsystems. The metabolism of microalgae can be favorably manipulated to increase lipid productivity through environmental stressors, and “green” techniques such as using flue gas as a carbon source and wastewater as a media replacement can lower the environmental impact of biodiesel production. Through life cycle assessment and the creation of process models, valuable insights have been made into the energy and material sinks of the manufacturing process, helping to identify methods to successfully scale up microalgae biodiesel production. Several companies are already exploring the microalgae industry, offsetting operating costs through isolation of co-products and careful unit operation selection. With numerous examples drawn from industry and the literature, this review provides a practical approach for creating a microalgae biodiesel facility.     

Land use change (LUC) analysis and life cycle assessment (LCA) of Brazilian soybean biodiesel

Biodiesel is an alternative to tackle global warming, especially for reducing greenhouse gases (GHG) emissions when replacing fossil fuels. However, it can compete for land with food production. Brazil is a global player on soybeans farming and most of the biodiesel produced in the country comes from it. This work proposes a new approach to evaluate its impact, associating land use change (LUC) analysis with life cycle assessment (LCA) in a representative Brazilian soybeans farming zone. LUC assessment used Landsat satellite imagery analysis from the years 1993 and 2013, and intergovernmental panel on climate change (IPCC) guidelines to estimate GHG emissions. LCA was based on field data collection processed with SimaPro^®. Results show that the increment on annual GHG emissions per hectare, derived from the apportioning total emissions for the period studied, was 50.16 kg CO₂ eq ha^?1 y^?1. From this increment, 97.1 % come from LUC, being the largest share from converting pastures to soybeans farming (81.2 % of the total emissions). However, in the area, a large share of converted pastures are degraded, acting as source of emissions, not as sink as considered by IPCC. At the same time, practices like no-tillage make soybeans a carbon sink. Therefore, results could change if alternative approaches were to be adopted, being a challenge for future work. Therefore, when considering biodiesel from soybeans, a close regard to local land use dynamics is essential to evaluate impacts. Besides, promoting more efficient use of land already cleared with the goal to avoid deforestation can turn biodiesel into a sustainable renewable energy source.     

The effect of greenhouse gas policy on the design and scheduling of biodiesel plants with multiple feedstocks

With the increasing attention to the environmental impact of discharging greenhouses gases, there has been a growing public pressure to reduce the carbon footprint associated with the use of fossil fuels. In this context, one of the key strategies is the substitution of fossil fuels with biofuels such as biodiesel. The design of biodiesel production facilities has traditionally been carried out based on technical and economic criteria. Greenhouse gas (GHG) policies (e.g., carbon tax, subsidy) have the potential to significantly alter the design of these facilities, the selection of the feedstocks, and the scheduling of multiple feedstocks. The objective of this article is to develop a systematic approach to the design and scheduling of biodiesel production processes while accounting for the effect of GHG policies in addition to the technical, economic, and environmental aspects. An optimization formulation is developed to maximize the profit of the process subject to flowsheet synthesis and performance modeling equations. Furthermore, the carbon footprint is accounted for with the help of a life cycle analysis (LCA). The objective function includes a term which reflects the impact of the LCA of a feedstock and its processing to biodiesel. A multiperiod approach is used to discretize the decision-making horizon into time periods. During each period, decisions are made on the type and flowrate of the feedstocks, as well as the associated design and operating variables. A case study is solved with several scenarios of feedstocks and GHG policies.     

Environmental impact of microalgal biomass production using wastewater resources

The current study provides a life cycle assessment (LCA) of microalgal biomass production using the effluent collected from the stabilization lagoon of a municipal sewage treatment as culture medium. Strains of two native microalgae from the stabilization lagoon (Desmodesmus sp. and Scenedesmus sp.) were grown in three different media: filtered effluent, autoclaved filtered effluent and conventional medium for cultivation of freshwater microalgae. Environmental analysis was carried out within the methodological framework of the LCA, by the life cycle impact assessment method ReCiPe 2008. A comparative analysis was performed for three endpoint categories: damage to human health, damage to ecosystem diversity and damage to resource availability. For both microalgal strains, the results confirmed that microalgal biomass production in non-autoclaved effluent has the lowest potential environmental impact. An additional analysis indicated that the potential environmental impact caused by discharge of effluents treated with microalgae is higher than the impact of untreated effluents. Despite the decrease in N and P in the effluent after microalgal treatment, the potential environmental impact of its discharge is strongly correlated with the electric consumption required for microalgal cultivation. This consumption could be lowered by decreasing the expenditure for illumination and mixing using outdoor microalgal cultivation.     

Use of Orthogonal Array Composite Designs to Study Lipid Accumulation in a Cell‐Free System

The development of clean, sustainable alternative energy sources is increasingly important. One promising alternative to depleting fuel reserves is algae‐based biodiesel fuel, which is both non‐toxic and renewable. Despite the tremendous potential of algae‐based biodiesel fuel, it has not yet been profitable because of the high cost per unit area of large cultivation. We present a novel application of Orthogonal Array Composite Designs (OACDs) to optimize lipid production of a cell‐free system for algae. An OACD consists of a two‐level fractional factorial design and a three‐level orthogonal array. We start with an initial screening experiment based on six chemicals using an OACD with 50 runs. Based on this experiment, two chemical compounds were removed and a follow‐up 25‐run OACD with four chemicals was performed. Our analysis shows that only three chemicals – nitrogen, magnesium, and phosphate – are essential for lipid accumulation, and a range of optimum combinations of these three chemicals is identified. The lipid accumulation for these three chemical combinations is substantially higher in comparison to the commercial medium, which contains 16 chemicals and soil water. This leads to a reduced cost of the chemical medium and increased efficiency of biodiesel production from the algal‐based cell‐free system, which can be used to significantly expand the use of biodiesel as a viable alternative to fossil fuels. Copyright © 2015 John Wiley & Sons, Ltd.     

Recent trends in policies, socioeconomy and future directions of the biodiesel industry

The growing uncertainty of available petroleum reserves and the associated environmental impacts from the usage of fossil fuels has led to a worldwide search for renewable energy sources. Biodiesel is currently placed at the forefront as the most viable alternative fuel for compression ignition engines as it can be produced from renewable sources through simple cost-effective transesterification, while being compatible with existing infrastructures. Despite these, biodiesel is still not economically feasible for large-scale adoption at present day, mainly due to the high cost of conventional feedstocks. Governmental policies, fiscal incentives and emissions laws have all shown to encourage the uptake of biodiesel in the early stages of market development. The rapid growth enjoyed by the biodiesel industry thereafter has raised concerns of various ethical issues, which must be addressed if the industry is to maintain its positive growth. The strategies required for a stable and sustained biodiesel industry will predominantly be based on the principles of a free market with minimal artificial interventions from policy makers, and the appropriate technological advances in production techniques and feedstocks options to stay competitive economically. This paper reviews the recent trends in global policies and legislative measures governing the economy of the biodiesel industry, and how these will impact the future outlook of the industry as a whole. Historical backgrounds and pertinent issues on socioeconomical and ethical aspects of the industry are also addressed here.     

Docosahexaenoic acid production from crude glycerol by <Emphasis Type="Italic">Schizochytrium limacinum</Emphasis> SR21

In our search for a substitute energy source, microalgal biodiesel has presented itself as a potential candidate. However, the development of biodiesel results in the overproduction of crude glycerol, which can cause undesirable environmental issues. The environmental harm can be minimized by converting crude glycerol into value-added products. One solution involves using a microalga Schizochytrium limacinum SR21 to convert crude glycerol into docosahexaenoic acid (DHA). DHA is an essential fatty acid, necessary for developing brain functions in infants and maintaining healthy brain activity in adults. In our study, the highest DHA productivity of 233.73 mg/g biomass was obtained using 3 % crude glycerol in Medium 2 at 20 °C under mixo/heterotrophic cultivation.     

Optimal site selection for solar power plants using multi-criteria evaluation: A case study from the Ayranci region in Karaman,Turkey

Currently, coal, oil and natural gas are mainly used for energy in most countries. These sources, called fossil fuels, are not renewable. Fossil fuels are limited, and their reserves are steadily decreasing. This situation causes the prices to rise constantly. On the contrary, renewable energy is clean, economical and unlimited. Turkey has a very high potential for renewable energy, and the Turkish government has made significant reforms for solar energy investments over the last decade. Site selection for solar power plants is a critical issue for large investments because of quality of terrain, local weathering factors, proximity to high transmission capacity lines, agricultural facilities and environmental conservation issues. Multi-criteria evaluation is a tool that allows one to choose the best criterion among multiple and offer a structure with a wide range of applications. In this paper, the ideal locations for solar power plant were selected using the geographic information system and analytic hierarchy process which is one of the multi-criteria evaluation methods. The resulting land suitability was grouped into three categories: low suitable, suitable and best suitable using an equal interval classification method. Consequently, 15,550 ha or 6.23% of the evaluated region was determined as the best suited areas for solar power plants.     

Optimum lipid production using agro-industrial wastewater treated microalgae as biofuel substrate

Abundant wastewater discharges from palm oil industries in tropical nations being a valuable resource of biodiesel need proper exploration. Research hinted that such wastewater as economical nutrient source or substrate can support the cultivation of microalgae. In this experiment, we have tested the growth and lipid production of five different microalgal strains in palm oil mill effluent (POME). POME as a biofuel substrate is demonstrated to be lucrative for microalgae-assisted lipids production. POME is rich in macro- and micronutrients can be used as a growth medium for algal growth in order to reduce the growth medium cost and environmental pollutions. Among the five microalgal strains tested, Chlorella sorokiniana revealed optimum biomass and lipid production. The productivity was evaluated in terms of chlorophyll content, growth rate, biomass, and lipid content, which discerned to be 0.099/day, 8.0 mg/L day and 2.68 mg/mg cell dry weight (CDW). Furthermore, in this study, an optimization study was carried out to enhance the microalgae to produce high lipid content using carbon-to-nitrogen ratio and different light/dark periods. The presence of nitrogen combined glucose (with a carbon-to-nitrogen ratio 100:7) as an alternative source to carbon displayed higher lipid production of 2.68 (mg/mg CDW) by C. sorokiniana. This study confirms that 8:16 h light/dark condition at C:TN ratio of 100:7 supported to produce high lipid content of 17 mg lipid/mg CDW. The above results revealed that POME could be a suitable growth media for the alga C. sorokiniana to improve the maximum lipid yield for biofuels production.     

Optimization and sensitivity study of biodiesel synthesis from Jojoba oil using mixed-integer programming

Jojoba oil-based biodiesel is promising alternative fuel due to its versatile properties. Renewable transportation fuels are considered as promising alternatives to conventional fuels. The physical and chemical properties of these fuels enabled them to be used in modern internal combustion engines; this makes them attractive for use as direct replacements or as additives of fossil fuels. Jojoba oil is extracted from Jojoba seeds, and it is an excellent feedstock for biodiesel after the transesterification process. The plant is highly adaptable to harsh weather including salty water, desert, and hot temperatures; thus, it can be grown in Saudi Arabia. This research work comprises a detailed optimization study of biodiesel production from Jojoba oil using mixed-integer programming. golden section search method was used for the optimization and sensitivity study was conducted for reaction time and temperature. The result shows that 54.1 minutes and 47.5 °C are the optimized reaction time and temperature to produce biodiesel which is considerably low as compared to previous studies.     

Sustainability assessment for biodiesel production via fuzzy optimisation during research and development (R&D) stage

Biodiesel is regarded as an important renewable fuel for meeting the global future energy demand and resolving the environmental problems (e.g. global warming). Despite its known advantages, it is still very critical to assess the sustainability of biodiesel production prior to greater expansion for commercialisation. Early hazard assessment when the process is still under development and design is very beneficial as process modifications to eliminate or reduce hazards can be made easier at lower costs. In this paper, inherent safety, health and environment (SHE) and economic performance (EP) analysis is conducted for biodiesel production during the earliest process lifecycle which is named as research and development (R&D) stage. Prior to the assessment, eight biodiesel production pathways via base-catalysed, acid-catalysed, enzymatic and supercritical transesterification using fresh or waste oil are classified. The inherent SHE assessments are conducted using the renowned methods of the Prototype Index of Inherent Safety (PIIS), Inherent Occupational Health Index (IOHI) and Inherent Environmental Toxicity Hazard (IETH) for inherent safety, health and environmental friendliness, respectively. The EP assessment is done using a proposed costing assessment based on operating cost and revenue. A systematic framework for assessing alternative biodiesel production pathways during the R&D stage is presented. Fuzzy optimisation approach is used to assess the pathway candidates based on multiple objectives of inherent SHE and EP. From the assessment result, it is found that biodiesel production based on enzymatic transesterification using waste oil is the most desirable pathway. Following the result of the assessments, several improvement actions for inherent SHE in biodiesel production are proposed and discussed.     

Modeling and simulation of coupled ethanol and biogas production

Ethanol produced from renewable resources is widely regarded as an option to substitute traditional fossil fuels. By coupling the ethanol production to biogas production, an energy autarkic process with minimum ecological footprint can be created. Capable engineering tools are needed to design such processes due to their complexity and the integration necessary. Here, we present a modeling strategy that can serve this task as it allows the steady-state flowsheet simulation of biotechnological production of alternative fuels from renewable resources. The modeling concept is explained and applied to a small-scale self-sustaining ethanol production (1,000 t/a fuel-grade ethanol). An adjunct pinch-analysis for heat integration further demonstrates the potential of the tool developed for the investigation and design of future production of fuel and chemical raw materials.     

Waste to energy: the effects of <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. on <Emphasis Type="Italic">Chlorella sorokiniana</Emphasis> biomass and lipid productions in palm oil mill effluent

Microalgae are recognised as promising feedstock for biofuel production. The feasibility in commercial scale microalgae cultivation could be enhanced by incorporating palm oil mill effluent (POME) as culture medium, for greater biomass growth and lipid production, together with POME bioremediation. The polluting POME is generated massively in Malaysia. POME contains high concentrations of carbon and nutrients, thus it is suitable to be applied for microalgae cultivation. The approach on waste to energy should be advanced. We studied the effects of applying Pseudomonas sp. on Chlorella sorokiniana CY-1 cultivation in POME. Pseudomonas sp. was found effective in POME decolourisation prior to C. sorokiniana CY-1 cultivation. Yet, microalgae biomass and lipid productions were higher in the non-decolourised POME. Pseudomonas sp. was as well-being co-cultivated with C. sorokiniana CY-1 in ratios of microalgae versus bacteria of 1:1; 2:1 and 1:2. Biomass of 2.04 g L^?1 and biomass productivity of 185.71 mg L^?1 d^?1 were attained in ratio of 1:1. Interestingly, the lipid content exhibited was excellent (16.04%), and about twofold higher than other ratios and the control (without bacteria). Fatty acids compositions were dominated by C16:0 (32.49%), C18:1 (24.06%) and C18:2 (20.28%), which were desirable fatty acids for biodiesel production. Effective POME bioremediation achieved with chemical oxygen demand, total nitrogen and total phosphorus removal of 53.7, 55.6 and 77.3%, respectively. Co-cultivation of microalgae and bacteria can be applied in the POME treatment plant. This allows satisfactory biomass and excellent lipid yields for biofuel production, as well as effective wastewater bioremediation.     

Strategies for Improving the Photocatalytic Hydrogen Evolution Reaction of Carbon Nitride-Based Catalysts

Due to the depletion of fossil fuels and their-related environmental issues, sustainable, clean, and renewable energy is urgently needed to replace fossil fuel as the primary energy resource. Hydrogen is considered as one of the cleanest energies. Among the approaches to hydrogen production, photocatalysis is the most sustainable and renewable solar energy technique. Considering the low cost of fabrication, earth abundance, appropriate bandgap, and high performance, carbon nitride has attracted extensive attention as the catalyst for photocatalytic hydrogen production in the last two decades. In this review, the carbon nitride-based photocatalytic hydrogen production system, including the catalytic mechanism and the strategies for improving the photocatalytic performance is discussed. According to the photocatalytic processes, the strengthened mechanism of carbon nitride-based catalysts is particularly described in terms of boosting the excitation of electrons and holes, suppressing carriers recombination, and enhancing the utilization efficiency of photon-excited electron–hole. Finally, the current trends related to the screening design of superior photocatalytic hydrogen production systems are outlined, and the development direction of carbon nitride for hydrogen production is clarified.     

Water consumption estimates of the biodiesel process in the US

As a renewable alternative to petroleum diesel, biodiesel has been widely used in the US and the world. However, its potential impact on water resources has not been much evaluated. This study investigates water consumption from the biodiesel process, which includes three stages: soybean irrigation, soybean-to-soybean oil processing, and biodiesel manufacturing, at both national and state levels. Mass-based allocation is performed and water consumption at the three stages is obtained on the basis of million gallons per year and gallon water per gallon biodiesel (gal/gal). The normalized water consumption (water intensity) of the irrigation, oil processing, and biodiesel production stages are 61.78, 0.17, and 0.31 gal/gal, respectively. The resulting total normalized water consumption is 62.26 gal/gal for the biodiesel process which is much lower than those reported in existing literature. It is shown that water consumption from the three stages varies significantly from state to state, which warrants the necessity of state-level water consumption analysis for better decision making in water resources management. Water consumption in potentially water-stressed states is also investigated and results show that currently these states represent 1.6 % of total water consumption associated with biodiesel production, 0.46 % of soybean harvest, and 27.61 % of biodiesel production capacity in the US.     

Preparation and characterization of hydrotalcite-like materials from flyash for transesterification

In the present study, attempts were made to synthesize Mg–Al hydrotalcite-like materials with bifunctional properties from flyash and flyash-based zeolite by coprecipitation method. The synthesized hydrotalcite and their corresponding Mg–Al mixed oxides obtained after calcination were characterized for their structural, compositional, thermal, and morphological properties. The synthesized hydrotalcite had Mg/Al ranging from 1.3 to 2.3. The activity of the synthesized catalyst was estimated in transesterification of mustard oil, and the effects of reaction time, catalyst concentration, and methanol-to-oil molar ratio on biodiesel production were also investigated. A maximum yield of 93.4 % was obtained with methanol-to-oil molar ratio of 12:1, 7 wt% catalyst concentration for 6 h of reaction at 65 °C. The average value of activation energy of biodiesel in the conversion range of 0.2 < X < 0.9 was 130.5 kJ mol^?1. This study showed the potential application of flyash and its use in modified Mg–Al hydrotalcite materials as heterogeneous catalysts in biodiesel production.     

Analysis of bioenergy production at different levels of integration in energy-driven biorefineries

In this paper, a techno-economic and environmental assessment is performed to compare the stand-alone process and biorefinery ways to produce biodiesel, ethanol and butanol as potential cases for bioenergy production using fresh fruit bunches as raw material. Different levels of integration are considered (e.g., mass and energy integration, non-conventional technologies) along with the analysis of the process scale to determine the economic profitability and environmental impacts of the proposed cases. The results demonstrated that the biodiesel production based on the biorefinery concept has a positive effect on the profitability of the stand-alone process at different scales. The economic results were compared with data reported in the literature. Furthermore, the life cycle analysis of the proposed cases suggested that the deployment of the biorefinery concept at different levels of integration in the oil palm supply chain reduced the environmental impact of the biodiesel production, which was selected as the hotspot of the evaluated cases.     

Choice of Life Cycle Assessment Software Can Impact Packaging System Decisions

A number of software packages are available that are designed to facilitate making environmental comparisons between different packaging options, to facilitate ‘green’ packaging design and assessment of the environmental aspect of sustainability. Some of these (e.g. SimaPro and GaBi) are full‐fledged ISO 14040/14044‐compliant programs for life cycle assessment (LCA). Others are more limited, but are designed to be much simpler to use (e.g. COMPASS and Package Modeling). A systematic comparison of the evaluation of several packaging systems using COMPASS, SimaPro, GaBi, and Package Modeling found significant discrepancies in LCA results from different software systems. Availability of common impact categories among the software limited comparisons to four categories: greenhouse gas emissions, fossil fuel/non‐renewable energy, eutrophication, and water depletion. Given a common set of basic packaging containers as input, results from the LCA software systems being studied disagreed on which container had the greatest environmental impact, and in some cases results were more than an order of magnitude different between software. Discrepancies in results occurred in all four impact categories, and all four software systems disagreed with each other at multiple points in the comparisons. If there is to be increasing use of LCA analysis in guiding packaging design, this issue must be fully understood and resolved. Copyright © 2015 John Wiley & Sons, Ltd.     

Energy policy shifts towards sustainable energy future for Malaysia

As a developing country, Malaysia’s prosperity and welfare depends heavily on having access to reliable and secure supplies of energy. As a result, the country’s future energy requirements have become a policy priority in recent years. Energy is essential for human life, and a secure and accessible supply of energy becomes important for the modern societies. Fossil fuels such as coal, oil, and natural gas are currently the world’s primary energy sources and continue to provide energy source to the world. These energy sources have depleted in reserves in recent years and they can also cause irreparably damage to the environment such as global warming and climate change. These environmental concerns can be addressed, to some extent, through more sustainable solutions such as the use of renewable energy resources. In Malaysia, the economic and environmental impacts of fossil fuels use have become hard to ignore. The government has introduced and implemented policy measures to address concerns surrounding the use of fossil fuels and to promote energy efficiency and renewable energy use. In this paper, we review the historical evolution of Malaysian energy policies and initiatives designed to secure diverse energy sources and avoid over-reliance on fossil fuels. In recent years, Malaysia has been catching up with global call to shift to renewable energy use and is now putting a focus on renewable energy in its future energy mix. The paper also discusses challenges and concerns over the future of sustainable energy of the country.     

Solar power plant site selection modeling for sensitive ecosystems

Clean Technologies and Environmental Policy - Reducing dependence on fossil fuels and increasing energy production based on renewable energy sources is a powerful alternative to alleviate global...