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Sustainability of algae derived biodiesel: A mass balance approach
Abstract
A rigorous chemical engineering mass balance/unit operations approach is applied here to bio-diesel from algae mass culture. An equivalent of 50,000,000 gallons per year (0.006002 m3/s) of petroleum-based Number 2 fuel oil (US, diesel for compression-ignition engines, about 0.1% of annual US consumption) from oleaginous algae is the target. Methyl algaeate and ethyl algaeate diesel can according to this analysis conceptually be produced largely in a technologically sustainable way albeit at a lower available diesel yield. About 11 square miles of algae ponds would be needed with optimistic assumptions of 50 g biomass yield per day and m2 pond area. CO2 to foster algae growth should be supplied from a sustainable source such as a biomass-based ethanol production. Reliance on fossil-based CO2 from power plants or fertilizer production renders algae diesel non-sustainable in the long term.
... Cheng and Timilsina [16] also underline that the selection and the development of high yield and oil rich microalgae strains is one of the most important pillars for the future of microalgal biodiesel production. For [17] algae are not a sustainable source of biomass for biofuel in the long term because of their reliance on fossil-based CO 2 from power plants and fertilizer production. ...
... Biodiesel from microalgae is characterized by: significantly higher impacts than other biodiesels for human toxicity, radiation, terrestrial acidification, freshwater eutrophication and marine ecotoxicity (because of spoilt lignite disposal and uranium mining) slightly higher impacts than the average of other biodiesels for global warming, ozone depletion, photooxidative formation (because of higher hexane volumes for oil extraction), particulate formation, metal depletion, fossil depletion, lower impacts than other biodiesels for land use, marine eutrophication, terrestrial and freshwater ecotoxicity. This is coherent with the results of the contribution analysis, namely the heavy weight on the overall environmental balance of fertilizer consumption and electricity consumption, and finally this result is consistent with the conclusion of other studies [7,17]. As already pointed out, this study does not account for indirect land use changes; however opposite to other biodiesel feedstocks, it is very likely that algae production facilities will not be installed on arable lands and hence will not create significant indirect land use changes. ...
... Alternative choices could have been made, such as a solar biomass dewatering, but we preferred to consider processes that were already individually tested to limit possible unrealistic assumptions rather than systematically choosing the most optimistic assumptions. In line with other studies [7,17], the overall analysis shows that it is necessary to minimize energy use and to reduce consumption of mineral fertilizers. It is also important to note that substantial energy stored as organic matter is to be found in the algae cake, after oil extraction. ...
... Cheng and Timilsina [16] also underline that the selection and the development of high yield and oil rich microalgae strains is one of the most important pillars for the future of microalgal biodiesel production. For [17] algae are not a sustainable source of biomass for biofuel in the long term because of their reliance on fossil-based CO 2 from power plants and fertilizer production. ...
... Biodiesel from microalgae is characterized by: significantly higher impacts than other biodiesels for human toxicity, radiation, terrestrial acidification, freshwater eutrophication and marine ecotoxicity (because of spoilt lignite disposal and uranium mining) slightly higher impacts than the average of other biodiesels for global warming, ozone depletion, photooxidative formation (because of higher hexane volumes for oil extraction), particulate formation, metal depletion, fossil depletion, lower impacts than other biodiesels for land use, marine eutrophication, terrestrial and freshwater ecotoxicity. This is coherent with the results of the contribution analysis, namely the heavy weight on the overall environmental balance of fertilizer consumption and electricity consumption, and finally this result is consistent with the conclusion of other studies [7,17]. As already pointed out, this study does not account for indirect land use changes; however opposite to other biodiesel feedstocks, it is very likely that algae production facilities will not be installed on arable lands and hence will not create significant indirect land use changes. ...
... Alternative choices could have been made, such as a solar biomass dewatering, but we preferred to consider processes that were already individually tested to limit possible unrealistic assumptions rather than systematically choosing the most optimistic assumptions. In line with other studies [7,17], the overall analysis shows that it is necessary to minimize energy use and to reduce consumption of mineral fertilizers. It is also important to note that substantial energy stored as organic matter is to be found in the algae cake, after oil extraction. ...
... A sustainable biomass generation system should protect the environment and avoid resource waste from taking place [84]. The development of an algal biorefinery that is sustainable requires the implementation of green measures in both the upstream and downstream processes, such as the selection of robust algal strains with improved growth characteristics and lipid productivity; the implementation of a cultivation strategy that is optimized for photosynthetic and nutrient use efficiency; and the implementation of a co-location strategy to capitalize on existing industrial infrastructure [41]. ...
... For commercial microalgal cultivation, the ORP offers a more cost-effective, easier-to-build, and viable solution. It is dependent on the system's boundaries, by the amount of biomass and the lipid/protein/carbohydrates compounds that can be attained during the process of cultivation phase, that the outcome of a life cycle evaluation is determined [84]. The use of open-ended raceway ponds to cultivate microalgae for biofuel and bioproduct generation on a large scale appears to be more cost-effective and practical than the use of closed PBRs. ...
To meet the rising demand for biofuel, food, and feed, as well as pharmaceuticals, microalgal-based biorefinery systems provide various advantages. Because of the worldwide energy crises, the future of microalgal biorefinery is attentively receiving prominence. Despite being renewable and carbon–neutral, microalgal-based technology produces net CO2 emissions. Due to poor market pricing for renewable fuels, current biomass conversion techniques are neither profitable nor long-term viable. The microalgal strain chosen is critical to the experiment's success. A comprehensive approach that considers all three aspects of environmental sustainability is required to successfully address these challenges. The process should never be jeopardized in any way that threatens its long-term viability. The issue of sustainability must therefore be addressed from the outset of every biorefinery project. It is necessary to investigate genetically altered microalgal strains with improved lipid content, light usage efficiency, pigment accumulation, and other features during the design phase of an algal-based biorefinery, among other things. This is due to the recent drop in crude oil prices, as well as the significant capital and investment costs associated with algae cultivation. Dewatering, harvesting, and lipid recovery must all be researched and developed at a low cost. To solve the problem of decreasing biomass productivities at bigger production scales, a new generation of photobioreactor designs, lighting strategies, and nutrient feed systems are required. To be successful, proponents of large-scale microalgae-based biorefineries must integrate social and sustainability sciences into their commercial plans. The current review explores the potential application of algal biomass for the production of biofuels and bio-based products. The variety of processes and pathways through which bioconversion of algal biomass can be performed are described in this review.
... Almost all sources of combustion-based candidate carbon dioxide sources, such as power plants, driers, natural gas processors, ethanol plants, and internal combustion engines, produce waste gas streams that contain many more compounds (inorganic and organic) other than carbon dioxide. 89,91 Numerous carbon dioxide bearing waste gases have been tested by various research groups with no groups reporting significant inhibition. 92,93 A drop in pH was reported which does indicate the need to ensure that culture system solutions remain within an acceptable pH range which often is neutral (∼7.0) except for systems using elevated pH levels to maintain species purity. ...
... 35,124−126 Superficial algal yields as high as 70 g/ m 2 /day have been reported with a range of 10−40 g/m 2 /day being most often reported and also being considered reasonable to sustain process feasibility. 20, 71,89,91,104 Cell yields based on reactor volume in the 0.02 to 0.2 g/L/day range are commonly reported. 35,71,123,124 Carbon dioxide is the most used source of carbon for the photoautotrophs. ...
Microalgae is envisioned by many experts to be one of the key future feedstocks for producing transportation fuels and other chemical products. The concept has many positive aspects inclusive of being fully renewable, minimal carbon footprint, and able to be implemented in low value agricultural lands. There has been a tremendous amount of developmental work done to commercialize the concept since the mid-1900s; however, the reality is that the cost for a gallon of microalgae oil is still too expensive to be considered a viable option to produce bio-based diesels at this time. Expanding the production of more than one or two products from a microalgae biorefinery is an economic must. Products derived from the algal cake must be developed and commercialized to offset the high cost of oil production. This paper will investigate the status of the concept and provide insight into directions needed to improve economic viability.
... The research program described has shown that the economic and environmental sustainability of a meaningful algal biofuels industry requires use of CO 2 and fertilizer nutrients that are not derived from fossil fuels [63][64][65] and that do not reduce the availability of fertilizer for agriculture. Recycling water or using otherwise impaired water can further increase the sustainability of biodiesel production from algae [64][65][66]. ...
... The research program described has shown that the economic and environmental sustainability of a meaningful algal biofuels industry requires use of CO 2 and fertilizer nutrients that are not derived from fossil fuels [63][64][65] and that do not reduce the availability of fertilizer for agriculture. Recycling water or using otherwise impaired water can further increase the sustainability of biodiesel production from algae [64][65][66]. One kilogram biodiesel requires approximately 3726 kg water, 0.33 kg nitrogen, and 0.71 kg phosphate if freshwater is utilized [66]. ...
The cultivation efforts within the National Alliance for Advanced Biofuels and Bioproducts (NAABB) were developed to provide four major goals for the consortium, which included biomass production for downstream experimentation, development of new assessment tools for cultivation, development of new cultivation reactor technologies, and development of methods for robust cultivation. The NAABB consortium testbeds produced over 1500kg of biomass for downstream processing. The biomass production included a number of model production strains, but also took into production some of the more promising strains found through the prospecting efforts of the consortium. Cultivation efforts at large scale are intensive and costly, therefore the consortium developed tools and models to assess the productivity of strains under various environmental conditions, at lab scale, and validated these against scaled outdoor production systems. Two new pond-based bioreactor designs were tested for their ability to minimize energy consumption while maintaining, and even exceeding, the productivity of algae cultivation compared to traditional systems. Also, molecular markers were developed for quality control and to facilitate detection of bacterial communities associated with cultivated algal species, including the Chlorella spp. pathogen, Vampirovibrio chlorellavorus, which was identified in at least two test site locations in Arizona and New Mexico. Finally, the consortium worked on understanding methods to utilize compromised municipal wastewater streams for cultivation. This review provides an overview of the cultivation methods and tools developed by the NAABB consortium to produce algae biomass, in robust low energy systems, for biofuel production.
... 55 However, these more favourable EROIs were achieved using labour intensive sub-tidal shallow waters off-bottom systems, and the EROI for offshore long line seaweed culture combined biogas and bioethanol production are lower at <1-2. 55 Although LCAs are an accepted methodology for assessing the potential of algal energy production systems, 170 Pfromm et al. 171 have suggested that algal biofuel LCAs tend to focus on materials rather than processes, and the expansion of LCAs to provide energy balances may not be an optimal approach. 171 In addition to the need for more data on seaweed biofuel there is also a need to develop alternative EROI models to those based on LCAs. ...
... 55 Although LCAs are an accepted methodology for assessing the potential of algal energy production systems, 170 Pfromm et al. 171 have suggested that algal biofuel LCAs tend to focus on materials rather than processes, and the expansion of LCAs to provide energy balances may not be an optimal approach. 171 In addition to the need for more data on seaweed biofuel there is also a need to develop alternative EROI models to those based on LCAs. ...
This review examines the potential technical and energy balance hurdles in the production of seaweed biofuel, and in particular for the MacroBioCrude processing pipeline for the sustainable manufacture of liquid hydrocarbon fuels from seaweed in the UK.
The production of biofuel from seaweed is economically, energetically and technically challenging at scale. Any successful process appears to require both a method of preserving the seaweed for continuous feedstock availability and a method exploiting the entire biomass. Ensiling and gasification offer a potential solution to these two requirements. However there is need for more data particularly at a commercial scale. © 2016 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
... Although it is important to distinguish between modelling assumptions and modelling errors (Clarens et al., 2011b) the assumptions used in many LCAs have been and can be challenged leading to a considerable degree of uncertainty in the validity of LCAs. Pfromm et al. (2011) has suggested that algal biofuel LCAs focus on materials rather than processes. They are essentially an inventory that lack the rigorous checks on data consistency offered by an engineering mass balance and the expansion of LCAs to energy balances therefore cannot succeed (Pfromm et al., 2011). ...
... Pfromm et al. (2011) has suggested that algal biofuel LCAs focus on materials rather than processes. They are essentially an inventory that lack the rigorous checks on data consistency offered by an engineering mass balance and the expansion of LCAs to energy balances therefore cannot succeed (Pfromm et al., 2011). Although LCAs are an accepted methodology for assessing the potential of algal energy production systems (Razon and Tan, 2011), it appears that current LCA software is unlikely to produce a rigorous dynamic mass and energy balance model. ...
There has been considerable discussion in recent years about the potential of micro-algae for the production of sustainable and renewable biofuels. Unfortunately the scientific studies are accompanied by a multitude of semi-technical and commercial literature in which the claims made are difficult to substantiate or validate on the basis of theoretical considerations.
To determine whether biofuel from micro-algae is a viable source of renewable energy three questions must be answered
:
a. How much energy can be produced by the micro-algae?
b. How much energy is used in the production of micro-algae?
c. Is more energy produced than used?
A simple approach has been developed that allows calculation of maximum theoretical dry algal biomass and oil yields which can be used to counter some of the extreme yield values suggested in the 'grey' literature. No ready made platform was found that was capable of producing an energy balance model for micro-algal biofuel. A mechanistic energy balance model was successfully developed for the production of biogas from the anaerobic digestion of micro-algal biomass from raceways. Preliminary calculations had suggested this was the most promising approach. The energy balance model was used to consider the energetic viability of a number of production scenarios, and to identify the most critical parameters affecting net energy production.
These were:
a. Favourable climatic conditions. The production of micro-algal biofuel in UK would be energetically challenging at best.
b. Achievement of ‘reasonable yields’ equivalent to ~3 % photosynthetic efficiency (25 g m-2 day-1)
c. Low or no cost and embodied energy sources of CO2 and nutrients from flue gas and wastewater
d. Mesophilic rather than thermophilic digestion
e. Adequate conversion of the organic carbon to biogas (≥ 60 %)
f. A low dose and low embodied energy organic flocculant that is readily digested, or micro-algal communities that settle readily
g. Additional concentration after flocculation or sedimentation
h. Exploitation of the heat produced from parasitic combustion of micro-algal biogas in CHP units
i. Minimisation of pumping of dilute micro-algal suspension
It was concluded that the production of only biodiesel from micro-algae is not economically or energetically viable using current commercial technology, however, the production of micro-algal biogas is energetically viable, but is dependent on the exploitation of the heat generated by the combustion of biogas in combined heat and power units to show a positive balance.
Two novel concepts are briefly examined and proposed for further research:
a. The co-production of Dunaliella in open pan salt pans.
b. A 'Horizontal biorefinery' where micro-algae species and useful products vary with salt concentration driven by solar evaporation.
... Although LCAs are an accepted methodology for assessing the potential of algal energy production systems [8], Pfromm et al. [9] have suggested that algal biofuel LCAs tend to focus on materials rather than processes. They are essentially an inventory that may lack the rigorous checks on data consistency offered by an engineering mass and energy balance; and the expansion of LCAs to provide energy balances is thus not an optimal approach [9]. ...
... Although LCAs are an accepted methodology for assessing the potential of algal energy production systems [8], Pfromm et al. [9] have suggested that algal biofuel LCAs tend to focus on materials rather than processes. They are essentially an inventory that may lack the rigorous checks on data consistency offered by an engineering mass and energy balance; and the expansion of LCAs to provide energy balances is thus not an optimal approach [9]. This paper describes the development of a mechanistic energy balance model for microalgal biofuel production from open raceway systems which is capable of determining the energetic viability of the process under different scenarios and harvesting methods. ...
The paper describes the construction of a mechanistic energy balance model for the production of biogas from anaerobic digestion of microalgal biomass grown in raceways, based on simple principles and taking into account growth, harvesting and energy extraction. The model compares operational energy inputs with the calorific value of the output biomass in terms of the energy return on operational energy invested (EROOI). Initial results indicate that production of microalgal biogas will require:
a) Favourable climatic conditions. The production of microalgal biofuel in the UK would be energetically challenging at best.
b) Achievement of ‘reasonable yields’ equivalent to ~3% photosynthetic efficiency (25 g m-2 day-1).
c) Low or no cost and embodied energy sources of CO2 and nutrients from flue gas and wastewater.
d) Mesophilic rather than thermophilic digestion.
e) Adequate conversion of the organic carbon to biogas (≥ 60%).
The model itself provides a powerful assessment tool both for comparison of alternative options and potentially for benchmarking real schemes.
... 5. benchmark, report and track on progress over time. 6. apply a common life cycle impact assessment (LCIA) method to effectively compare the overall product, system or process 'footprint' with its relevant alternatives. ...
... The existing published works reviewed here are related to microalgae LCA and are divided into three broad categories. The first covers the spectrum from energy, greenhouse gas and mass balance calculations, to high-level 'scoping' LCA studies [5][6][7]. These do not report beyond a limited set of metrics and/or do not appear to apply or present any discrete LCIA method. ...
Innovation towards a scalable and viable microalgae industry for renewable and sustainable bioenergy is greatly assisted by the application of life cycle assessment as a benchmarking tool to guide the process. This work examines existing studies in the field that have attempted to assess either the environmental impact and/or commercial viability of the microalgae value chain. Existing literature tends to omit established conventions of life cycle assessment practice, and/or lacks a common approach to boundary definition, functional units and impact assessment that would enable more effective comparison of options. A move towards a 'level playing field' methodology would enable strategic prioritization of research efforts to emerge that could lead to more rapid development of preferred products, cultivation and harvesting technologies, and downstream processing pathways.
... Life Cycle Assessment (LCA) is a compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle [55]. LCA based on biofuels has been done with no profitable results due to the economic and environmental impact. ...
... When microalgae are grown in sea water or wastewater, biodiesel production may consume much less potable water than conventional feedstockbased biodiesel production. In addition, other alternatives are (1) production of ethanol from algae starch after oil extraction, (2) usage of glycerol and residual biomass for energy conversion, (3) wastewater usage and water recycling once biomass was harvested, (4) cell wall disruption pretreatment to enhance oil extraction, (5) pH adjustment with biological flocculants to aid harvesting and (6) use of solar heat for drying [55,56,60,61]. In addition, other technologies to produce biofuels from algae have been proposed (pyrolysis, liquefaction). ...
Microalgae are photosynthetic microorganisms capable to produce lipids, carbohydrates, and proteins as major biomass fractions. Each of these have been studied to produce biofuels. As example biodiesel, bioethanol, biogas, bio-oil and biohydrogen by different processes and conditions. In addition, microalgae are considered an alternative for CO 2 emissions fixation since this gas is used by their metabolism. Based on this sustainable alternative, microalgae are considered feedstock to integrate a Bio-refinery, in which different products can be obtained from biofuels to food. In this article, in addition to the literature revision for biofuels production from microalgae, drawbacks and bottlenecks from microalgae technologies are discussed.
... Life Cycle Assessment (LCA) is a compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle (Pfromm et al., 2011). LCA based on biofuels has been done with no profitable results due to the economic and environmental impact. ...
... When microalgae are grown in seawater or wastewater, this biodiesel production may consume much less potable water than conventional feedstock-based biodiesel production. In addition, other alternatives are (1) production of ethanol from algae starch after oil extraction, (2) usage of glycerol and residual biomass for energy conversion, (3) water recycling once biomass was harvested, (4) cell wall disruption pretreatment by enzymatic lysis to enhance oil extraction, (5) pH adjustment with biological flocculants to aid harvesting and (6) use of solar heat for drying (Lardon et al., 2009;Pfromm et al., 2011;Yang et al., 2011). developed an economic analysis for microalgae production and CO 2 fixation costs. ...
One of the most important industrial activities related to the greenhouse gases emissions is the cement manufacturing process, which produces large amounts of carbon dioxide (CO2). Only in 2010, 8% of CO2 global emissions were due to cement industry. In this work, the use of CO2 released by the cement sector is described as potential gas for microalgae culture since their biofixation efficiency is higher than terrestrial plants. Therefore, transformation of polluting gas fluxes into new and valuable products is feasible. In addition, bulk applications such as wastewater treatment and biofuels production can be coupled. Finally, microalgae biomass can be also used for the production of valuable compounds such as pigments, food supplements for both humans and animals, and fertilizers. In this review, flue gas emissions coupled to microalgae cultures are described. In addition, since microalgae can produce energy, the biorefinery concept is also reviewed.
... The Saccharomyces cerevisiae is being used to convert molasses and cellulose to bioethanol. Similarly, Green algae are used to produce biodiesel by utilizing sunlight (Scott et al., 2010;Krohn et al., 2011;Patil et al., 2011;Pfromm et al., 2011). Upscaling of its production and utilization will go a long way in drastically reducing the use of fossil fuels and GHG emissions by way of manufacturing of petroleum products, power generation, etc. ...
The negative effects of climate change are occurring all over the world. These include rising temperature and sea level, unseasonal rainfall, drought, floods, etc. Agricultural production is also severely getting affected due to climate change. Climate smart agriculture (CSA) is a sustainable approach to increase the adaptability of agricultural production systems to improve crop production under changing climatic conditions. CSA also draws attention to reduce greenhouse gas (GHG) emissions and to improve carbon stability in soil. Agriculturally beneficial microorganisms assume significant role in climate smart agriculture. They can help to enhance adaptation, mitigation and build resilience to climate change effects. Plant beneficial microorganisms are fundamental to different bio-geochemical process in soil viz., organic matter decomposition, carbon cycle, nitrogen cycle, phosphate solubilization and mobilization, nitrogen fixation, and acquisition of micronutrients. Microorganisms also facilitate the crop plants to withstand various abiotic stresses viz., elevated temperature, elevated CO2, moisture stress, salinity stress, and metal toxicity. Methanotrophs, methylotrophs and photosynthetic microorganisms play the important role in mitigating the greenhouse gases. Soil microorganisms also have crucial role in carbon sequestration in soil. Microbial-based technology is low cost, eco-friendly and sustainable. Biofertilizers and biopesticides being the major components of integrated nutrient and insect-pest management, as well as one of the key elements of climate smart agriculture, the application of beneficial microorganisms reduces the use of synthetic agro-chemicals, sustains the soil health and soil biodiversity, and enhances the plant growth.
... It is also necessary to reach the right balance between different parameters, such as oxygen, CO2, pH, light intensity, products and by-products concentrations. In an optimal environment with adequate nutrients, microalgae usually double their biomass in 24 h (3.5 h in the exponential growth phase), because of this they require very short harvest cycles (1-10 days) [17]. ...
The increasing global demand for biofuels for energy security and to reduce the effects of climate change has created an opportunity to explore new sources of biomass, of which, microalgae is the most promising one. The Laboratory of the Biomass Research Centre (CRB, University of Perugia) is equipped with a photobioreactor that is used to cultivate microalgae under batch conditions. Tests were carried out a temperature of 22 °C and a Photosynthetic Photon Flux Density of 140 μE·m −2 ·s −1. Cultures were characterized in terms of biomass produced and lipid fraction distribution. The novelty of this paper is the measure of the fuel properties of Selenastrum capricornutum, a new strain for biodiesel production. In particular, after the microalgae have been collected and oil has been extracted, this has been transesterified using a methanol/NaOH solution. The resulting biodiesel has been analyzed with a high-resolution gas chromatograph to determine the concentration of the different methylesters.
... Algae offer the potential of higher lipid productivity using waste or salt water in the areas that not presently used for agricultural food production [24]. 3G biomass has the significant merits of not competing with the land, low lignin content, less energy input and reduced food-fuel competition [25]. They are engineered explicitly through molecular biology techniques to improve the biomass conversion to biofuels [26,27]. ...
... Generally, open raceway ponds are relatively inexpensive, easier to construct, and feasible option for the commercial microalgal cultivation as compared to closed PBR that are costly but have better process control, ability of reaching higher culture density and productivity. According to ISO 10440, LCA is a "compilation and evaluation of the inputs and outputs and the potential environmental impacts of a product system throughout its life cycle" [23]. It is a significant tool for assessing the environmental aspect of a product or process for its sustainable production. ...
The potential of microalgae as a source of renewable energy is of considerable interest. During recent initiatives being taken at the 2015 United Nations Climate Change Conference (COP21) held in Paris, about 196 attending nations have set goals to limit global warming to less than 2 degrees Celsius (°C) compared to pre-industrial levels and move toward attaining zero net anthropogenic greenhouse gas emissions by the second half of the twenty-first century. This necessitates curtailing the usage of non-renewable resources, primarily fossil fuels, which are one of the biggest contributors of GHGs and explore more bio-based alternatives, such as microalgae. A key attraction of algae as biofuel feedstock lies in the potential for high annual oil productivity per unit of area. Due to the wide availability and potential of cultivation or occurrence in naturally occurring habitats including harsh environments such as extreme temperatures, salinity, pH, multiple products could be obtained from a variety of algal species. This multi-product paradigm makes it a suitable candidate for the biorefinery concept. An algal biorefinery aims to increase value from green biomass by recovering every component for its use as feedstock in myriad applications such as biofuels, food and feed, fertilizer, and pharmaceuticals. However, existing biorefinery methods have to be duly modified, improved, and widely adapted for the sustainable production of microalgal biomass and its associated benefits. Thus, this chapter presents a framework to analyze sustainability as cultivation, harvesting, and processing of microalgal biomass and use of bioenergy/refinery has a large range of associated sustainability issues. The process economics of biomass facility production, carbon sequestration, and waste mitigation have been discussed to comply various sustainability criteria for the successful implementation of algal-based biorefinery at commercial scale.
... Nonetheless, closed PBRs exhibit higher energy consumptions and investment costs, which limits the use of this technology for the cultivation of microalgae for bio-fuel applications. LCAs of microalgae bio-fuels typically reveal negative energy gains and environmental impacts ( Pfromm et al., 2011). However, Collet et al., (2011 reported that the biogas production from algal biomass can strongly compete with the other microalgal based biofuels such as biodiesel. ...
The interest in microalgae for wastewater treatment and liquid bio-fuels production (i.e
biodiesel and bioethanol) is steadily increasing due to the energy demand of the ultra-modern
technological world. The associated biomass and by-product residues generated from these processes
can be utilized as a feedstock in anaerobic fermentation for the production of gaseous bio-fuels. In
this context, dark fermentation coupled with anaerobic digestion can be a potential technology for
the production of hydrogen and methane from these residual algal biomasses. The mixture of these
gaseous bio-fuels, known as hythane, has superior characteristics and is increasingly regarded as an
alternative to fossil fuels. This review provides the current developments achieved in the conversion
of algal biomass to bio-hythane (H2 + CH4).
... Several papers focus on specific criteria such as GHG mitigation ( [31,52,55,75,85,106]), ILUC impact [117,17,27,41,6,74], as well as the impact on food prices [125,62,7,88], etc. Other papers focus on a wider range of sustainability criteria, but for a particular biofuel option [123,28,81,90,94,116]. The sustainability assessment of biofuels requires dealing with a wide range of criteria, whether economic, social, environmental or legal issues [115,48,80]. ...
Measuring biofuel sustainability requires dealing with a wide variety of complex and conflicting values at stake. Consequently, the biofuel capacity to contribute to one specific value cannot lead to any absolute conclusion about the overall sustainability of biofuel. The scope of the sustainability concept may vary depending on individuals’ preferences, the time scale and the geographical region. Based on the 5 pillars sustainability concept that includes social, economic, environmental, legal and cultural considerations, the present study proposes to assess several biofuel sustainability options for France by 2030 through a stakeholder-driven approach. Rather than seeking to reach a consensus, our approach allows us to capture the wide diversity of stakeholders’ perspectives and preferences. French stakeholders perceive 22 different sustainability criteria for biofuels with a very low level of agreement between the different segments of professions (feedstock producers, biofuel producers, refining industry, fuel distributors, car manufacturers, end-users, government and NGOs). In order to operationalize the sustainability assessment, a set of indicators has been identified with stakeholders that allows us to measure the capacity of biofuels to fulfill each of their criteria. Seventeen biofuel options were assessed with regards to economic, social, environmental, cultural and legal considerations, allowing the identification of the strengths and weaknesses of each biofuel.
... To evaluate the environmental impact of microalgae oil extraction, LCA method is frequently used to assess the associated energy inputs and outputs and the potential environmental impacts of a product system (Lardon et al., 2009;Yang et al., 2011;Pfromm et al., 2011). This systematic assessment can further identify critical steps that are responsible for environmental impacts (usually those bottleneck processes), which on the other hand points a specific direction to solve it. ...
Environmental impact of CO2-expanded fluid extraction technique in microalgae oil acquisition was quantitatively analyzed using life cycle assessment (LCA) method and compared with other available extraction techniques. It was found that CO2-expanded fluid extraction technique exhibited only one-tenth of environmental impact over other extraction methods, particularly on organic respiratory and climate change. Achieved low environmental impact was mainly attributed to the high extraction efficiency that further allows it for operating in mild pressure and shortened period of time, which dramatically decreases the energy consumption and afterwards environmental impacts. Utilizing renewable energy for CO2-expanded fluid extraction would further lower its environmental impact by minimizing carbon footprint resulting from electricity generation. Importantly, based on water-energy nexus consideration, the low environmental impact along with low energy consumption of CO2-expanded fluid extraction technique arises an opportunity to regard microalgae oil an energy storage vessel in response to the intermittent nature of renewable energy. This would be a new incentive for the development of microalgae oil production.
... Most of the MCDM methods are merely used for sustainability assessment to support the decision-makers/stakeholders in the selection of the best scenario. Such methods are also used for assessing the sustainability of biofuels (Meester et al., 2012; Pfromm et al., 2011; Delrue et al., 2012). These studies are of vital importance for China's decision-makers/stakeholders to select the most sustainable pathway for biofuel production among multiple alternative scenarios; however, they cannot obtain the answers for what are the key problems existing in China's biofuel industry and how to enhancing the sustainability of China's biofuel industry. ...
Biofuel as a promising pathway for substituting the traditional fossil fuels, mitigating environmental contaminations, and enhancing the energy security has attracted more and more attention in China. This study aims at identifying the critical success factors for promoting the sustainable development of biofuel industry and helping the stakeholders/decision-makers to draft the appropriate strategic measures for enhancing the sustainability of biofuel industry in China. A generic methodology in which the decision-makers are allowed to use linguistic terms to express their views and options, multiple decision-makers are allowed to participate in the decision-making, has been developed to prioritize the factors influencing the sustainability of biofuel industry and to identify the cause-effect relationships among these factors. The three factors, including government support degree, competitiveness, and local acceptability are identified as the most critical factors for promoting the sustainable development of biofuel industry in China, but they are all effects rather than the origins of the problems existed in the biofuel industry of China. In contrast, maturity, safety and reliability, complexity, conversion efficiency, and investment cost are the most important causes, and they are also the origins of the problems existed in the biofuel industry of China. Six effective strategic measures including popularizing the use of biofuels in large scales, subsidies and tax exemption policies, investing more on R&D on biofuel technologies, encouraging more private enterprises and joint ventures to participate in the biofuel industry, developing the integrated utilization manner of biofuels by further developing the byproducts of biofuels, and popularizing the use of biodiesel and bioethanol among the vehicle users through publicity and education have been proposed for promoting the sustainable development of China’s biofuel industry according to the obtained results.
... It could be seen that producing oil from algae and subsequently biodiesel as well as other products is considered highly efficient by many researchers [133][134][135]. The processes of cultivation, oil extraction, and final conversion into biodiesel are basically comparable to those of other edible crops such as soy, sunflower, and palm. ...
Microalgae are considered one of the most promising feedstocks for biofuels. Interest in algae-based biofuels and chemicals has increased over the past few years because of their potential to reduce the dependence on crude oil-based fuels and chemicals. Algae is the most suitable and sustainable feedstock for producing green energy. However, numerous challenges associated with declining fossil fuel reserves as energy sources have accounted for a shift to biofuels as alternative product from algae. Algae is a source for renewable energy production since it can fix the greenhouse gas (CO2) by photosynthesis and does not compete with the production of food. This chapter, therefore, presents a review on the prospects of algae for biofuel production and also highlighted in this article is the macroalgae-based biofuels energy products obtained from algae as the raw biomass. In a nutshell, algae are the most sustainable fuel resource in terms of environmental issues.
... It could be seen that producing oil from algae and subsequently biodiesel as well as other products is considered highly efficient by many researchers [133][134][135]. The processes of cultivation, oil extraction, and final conversion into biodiesel are basically comparable to those of other edible crops such as soy, sunflower, and palm. ...
This chapter aims to review the previous lighting technologies and discuss the impact of lighting design and user behaviour to the energy consumption of lighting as well as life cycle assessment of luminaires. Energy for lighting can consume between 31 % (in retail store applications) and 60 % (in educational settings) of an organization’s electricity budget. The price of electricity has never stopped its rising trend due to the global issue of energy scarcity. Therefore, a lot of efforts have been made in seeking ways to cut the electricity bill by reducing the energy consumption of lighting system and operating more efficiently. Insight will be shed onto the status of energy consumption by lighting, current lighting technologies, design and control, and the life cycle assessment of luminaires. Finally, a less resource depriving and low energy consuming way of using artificial lighting is proposed.
... It could be seen that producing oil from algae and subsequently biodiesel as well as other products is considered highly efficient by many researchers [133][134][135]. The processes of cultivation, oil extraction, and final conversion into biodiesel are basically comparable to those of other edible crops such as soy, sunflower, and palm. ...
The construction industry and building materials consume a large amount of resources and energy during its extraction, production, construction, throughout its use and even demolition process, hence causing high impacts to the natural environment. Apart from an increase in energy use, these impacts of materials range from ecological degradation, harm to human health and global warming. In order to reduce the impacts, an assessment and analysis of building materials is crucial prior to the design and construction of buildings to predict the risks and enable the decision makers to minimize those risks. This chapter gives an overview of the lifecycle approach in material selection and the assessment and analysis of materials used in the construction based on ISO 14040:2006 and ISO 14044:2006. It also presents the results of the testing on life cycle assessment of common building materials adopted in mosque construction in Iraq based on five categories: global warming, ozone depletion, human toxicity, acidification and eutrophication. This study identifies the stages in which the materials have greater impact and give recommendation in reducing the overall impact of the materials used.
... It could be seen that producing oil from algae and subsequently biodiesel as well as other products is considered highly efficient by many researchers [133][134][135]. The processes of cultivation, oil extraction, and final conversion into biodiesel are basically comparable to those of other edible crops such as soy, sunflower, and palm. ...
Conventional methods to analyze building energy are of limitation and difficult to determine the best building envelope structure, best material thermal properties, and the best way for heating or cooling. In this paper, the research on the inverse problem for phase change materials and the application in building envelope by our group was reviewed, which can be used to guide the building envelope thermal performance design, material preparation and selection for effective use of renewable energy, reducing building operational energy consumption, increasing building thermal comfort, and reducing environment pollution and greenhouse gas emission. This paper also presents some current problems needed further research.
... It is likely that they are present here only at very low concentrations since > 99% of the initial N in the algae appears in the biocrude and aqueous phase. Phosphorus is an important element for algal cultivation and its limited quantities emphasize the need to recover and recycle it for sustainable production of algal biofuels [62]. The P content of the algal feedstock is 0.6%. ...
Algae biomass is a promising source of liquid biofuels. Hydrothermal liquefaction can convert wet algae biomass into a ???biocrude??? oil with similar properties to crude petroleum, but it also produces an aqueous co-product (AqAl) that contains most of the nitrogen and phosphorus from the initial biomass and up to 40% of the carbon. Efficient recycle of these components within the system is crucial, yet direct feeding of AqAl back to algae ponds has proven problematic. In this work, we investigate the use of an intermediate bacterial culture to initially utilize this challenging product.
In the first part, we investigate the properties of products formed from Nannochloropsis oculata algae biomass processed under a variety of hydrothermal reaction conditions. We then use AqAl as the sole C/N/P source for bacterial culturability studies on bacteria Escherichia coli and Pseudomonas putida. We determine that bacterial culture is feasible and the bacterial strains studied can utilize up to 43% of the organic carbon present. However, there is an inhibitory effect imposed by the AqAl.
In the second part, we improve the bacterial strains??? growth phenotypes through adaptive evolution in media of increasing AqAl concentration. Evolved E. coli and P. putida strains can grow at rates 104% and 260% faster and reach cell concentrations 24% and 61% higher, respectively, in AqAl media. The full genomes of improved strains are determined and mutations conferring benefits are identified. Some of these mutations are individually introduced to E. coli to investigate their specific effects. Also, gene expression levels between a top-performing evolved strain of E. coli and its parent strain are compared.
Finally, we investigate the utility of a microbial processing step on an integrated algae biofuel process in two ways. First, we investigate the possibility of using microbial biomass as a supplemental feedstock for hydrothermal reactions, observing oil yields upwards of 75% of that of algae. Second, we investigate the effects bacterial pre-culture has on AqAl pertaining to its suitability as an algae growth medium component.
We conclude that an intermediate bacterial culture could contribute to the overall efficiency and sustainability of an algae biofuel process.
... Urea, which is the most commonly used chemical nitrogenous fertilizers, is produced through very well-known Haber-Bosch process which rely on fossil fuels (Vance, 2001;Pfromm et al., 2011). Excessive use of chemical fertilizers is responsible for global warming, for example, assuming a recommended rate of 150:60:40 kg N:P 2 O 5 :K 2 O hectare −1 applied through urea, diammonium phosphate (DAP) and muriate of potash (MOP) for the cultivation of maize, ∼599 kg CO 2 equivalents are produced on account of fertilizer production and their transport (Singh et al., 2015). ...
High volumes of lipid extracted microalgal biomass residues (LMBRs) are expected to be produced upon commencement of biodiesel production on a large scale, thus necessitating its value addition for sustainable development. LMBRs of Chlorella variabilis and Lyngbya majuscula were employed to substitute the nitrogen content of recommended rate of fertilizer (RRF) for Zea mays L. The pot experiment comprised of 10 treatments, i.e., T1 (No fertilizer); T2 (RRF-120 N: 60 P2O5: 40 K2O kg ha⁻¹); T3 to T6—100, 75, 50, and 25% N through LMBR of the Chlorella sp., respectively; T7 to T10—100, 75, 50, and 25% N through LMBR of Lyngbya sp., respectively. It was found that all LMBR substitution treatments were at par to RRF with respect to grain yield production. T10 gave the highest grain yield (65.16 g plant⁻¹), which was closely followed by that (63.48 g plant⁻¹) under T5. T10 also recorded the highest phosphorus and potassium contents in grains. T4 was markedly superior over control in terms of dry matter accumulation (DMA) as well as carbohydrate content, which was ascribed to higher pigment content and photosynthetic activity in leaves. Even though considerably lower DMA was obtained in Lyngbya treatments, which might have been due to the presence of some toxic factors, no reduction in grain yield was apparent. The length of the tassel was significantly higher in either of the LMBRs at any substitution rates over RRF, except T6 and T7. The ascorbate peroxidase activity decreased with decreasing dose of Chlorella LMBR, while all the Lyngbya LMBR treatments recorded lower activity, which were at par with each other. Among the Chlorella treatments, only T5 recorded significantly higher values of glutathione reductase activity over RRF, while the rest were at par. There were significant increases in carbohydrate and crude fat, respectively, only in T4 and T3 over RRF, while no change was observed in crude protein due to LMBR treatments. Apparently, there was no detrimental effect on soil properties, suggesting that both the LMBRs can be employed to reduce the usage of chemical fertilizers, thus promoting maize crop production in a sustainable manner.
... Nevertheless, to date, only a few marine algae species have been genetically manipulated successfully. The development of this technology is in its early stages and much remains to be done to optimize the business models and lifecycle analysis, as well as in testing pilot-and demonstrationscale systems (Frank et al., 2013;Han et al., 2014;Kumar et al., 2010;Pfromm et al., 2011;Resurreccion et al., 2012;Shirvani et al., 2011;Sills et al., 2013). ...
The decreasing supply of fossil fuels and their impact on global warming have led to an increasing demand for their replacement by sustainable renewable biofuels. Microalgae may offer a potential feedstock for renewable biofuels; they are capable of converting atmospheric CO2 to substantial biomass and valuable biofuels, which is of great importance for the food and energy industries. Optimization of microalgal species depends upon the selection of strains and their subsequent genetic/metabolic engineering. Modifications target the improvement of cellular activities by the manipulation of enzymatic, transport, and regulatory functions using biological modulators and/or engineering methods to refine sustainable biofuel production. In this context, rapidly developing system-level "omics" analyses (genomics, transcriptomics, proteomics, metabolomics), which are both sensitive and quantitative, along with the availability of systems biology models (for a better understanding of metabolic networks) will provide useful insights for the genetic engineering of marine microalgae to further optimize bioenergy production.
... [16][17][18] In fact, some studies deemed algal biofuel unsustainable in the long run because of its reliance on synthetic fertilizer production. 19 With every new technology, it is important that its environmental impacts are very clearly understood before it is applied on a large scale. 20 For a process to be sustainable, it has to be sustainable environmentally as well as economically. ...
“Cradle-to-gate” life cycle analysis surrounding five algae-to-fuel/fuel precursor scenarios was studied. The different processes modeled were: an open pond producing either triacylglycerides (TAG) or free fatty acid methyl ester (FAME); a solar-lit photobioreactor producing either FAME or free fatty acids; and a light emitting diode irradiated (LED-lit) photobioreactor-producing TAG. These processes were chosen from amongst the simplest to most sophisticated approaches available in literature. The scenarios of production with open ponds are close to being sustainable environmentally. On the other hand, the production scenarios with solar-lit and LED-lit photobioreactors are both far from being sustainable. The reason for this is the higher embedded and operating life-cycle impacts associated with the materials in the growth reactor (and some other equipment) in these two types of production facilities, as well as the artificial photon source used in the latter. Many difficult-to-achieve improvements are required to make these processes less energy intensive. Algae strains with higher lipid productivity as well as changes in the number, the complexity, and energy expenditures in operation steps are always required to reduce overall life-cycle impacts when production of commodity fuels is the focus. An important perspective to keep in mind with algae-based processes is that there are currently no significant economies-of-scale with the environmental impacts for growth systems, since they are additive above a baseline production level.
... Microalgal growth can be better understood by the interaction of algal biofuel production with the environment through the development of models describing their usefulness for designing efficient bioreactors, predicting process performance, and optimizing operating conditions [168,169]. Models of life cycle assessment (LCA) can provide information about technology, economics, and sustainability [159], along with an evaluation of the inputs and outputs and their potential environmental impacts of a product [170]. Notably, the final outcome may vary with different culture systems, and the different methods used for biomass harvest and oil refinery [171][172][173][174]. ...
Increasing demand of biofuels is inevitable today considering the adverse impact of fossil fuels on environment, issue of its sustainability, rising price and dependence on foreign countries. However, the question remains on how to produce biofuels in cost effective manner from the non-food resources. The non-food agricultural and forestry residues have recalcitrant biomass that is difficult to hydrolyze via enzymes, and presence of non-conventional pentose sugars and inhibitors makes the sugar fermentation into ethanol a formidable task. Besides, ethanol has its inherent issue of having low energy density and hygroscopic nature, encouraging scientists to look for alternative fuels, such as butanol and hydrocarbon. Algae are another non-food feedstock that is being explored for fuel production, but its low growth rate and low lipid yield in fluctuating environmental growth condition is of great concern. Synthetic biology with its new tools and applications is likely to play a central role in addressing these issues.
... This high fertilizer demand is a challenge to the sustainability of microalgae biomass production, and several life cycle analyses studies have shown that the energy required for synthetic fertilizer production contributes significantly the total energy demand for microalgal biofuels (Lardon et al. 2009;Clarens et al. 2010;Benemann et al. 2012). Production of N fertilizers through the Haber-Bosch process is highly energy-intensive and is reliant on fossil fuels (Smil 2002;Pfromm et al. 2011). Extraction and processing of mineral phosphates for production of P fertilizer is also energy-intensive (Johnson et al. 2013). ...
Production of microalgal biomass requires large amounts of nitrogen (N) and phosphorus (P). The sustainability and economic viability of microalgae pro- duction could be significantly improved if N and P are not supplied by synthetic fertilizers but with wastewater. Microalgae already play an important role in wastewater treatment, yet several challenges remain to optimally convert waste- water nutrients into microalgal biomass. This book chapter aims to give an over- view of the potential of using wastewater for microalgae production, as well some challenges that should be taken into account. We also review the benefits of combining microalgal biomass production with wastewater treatment.
... According to ISO 10440, LCA is a "compilation and evaluation of the inputs and outputs and the potential environmental impacts of a product system throughout its life cycle". [122]. Thus, LCA gives us an overall picture of the superior quality of energy dynamics, reliability and environmental impacts [118]. ...
The interest in algae based biofuels and chemicals has increased over the past few years because of their potential to reduce the dependence on petroleum-based fuels and chemicals. Algae is touted to be the most suitable and sustainable feedstock for producing green energy as the whole process is carbon—neutral in nature and can also be utilized for environment cleaning applications. This review article mainly focuses on how algae can be used as an efficient and economically viable biorefinery feedstock. An effective biorefinery using algae can only be constructed through its integration with other industries. To make sense of the algal biorefinery concept, there is a need to establish a proper connection between the various input and output streams of the products, as well as the services to be provided by the participating industries. Also highlighted in this article, is the entire spectrum of energy and non energy products that can be obtained using algal biomass as the raw material.
... As a consequence, a proper assessment of the mass balance is mandatory to calculate these generated credits. The LCI consists in a compilation of inputs and outputs, with generally a ''black box approach'' [55]. Mass balance approach is based on a more consistent analysis, specifying process inputs and calculating the outputs. ...
... In addition, algae could grow 7-31 times faster than palm oil plants, and 50% of their weight consists of oil [28]. Pfromm et al. [30] studied the economics of biodiesel from algae using the principle of conversion of mass and concluded that algal biodiesel could be produced sustainably with the exception of natural gas to produce nitrogen-based fertiliser in the long term. Overall, the commercialization of algae to biodiesel during initial stages will depend on the support of the government [31,32]. ...
Growing concern for the environment, increasing stringent standards for the release of chemicals into the environment and economic competiveness have led to more environmentally friendly approaches that have resulted in greater pollution prevention via waste reduction and efficiency maximisation. Green process engineering (GPE) is an important tool that could make significant contributions in the drive toward making hazardous and wasteful processes more sustainable for the benefit of the economy, environment and society. This article highlights the guidelines that could be used by scientists and engineers for designing new materials, products, processes and systems. Few examples of current and future applications of GPE, particularly in the areas of biofuels, supercritical fluids, multi-functional reactors and catalytic processes, have been presented.
... [14,15] The major advantage on usage of biofuels is its environmental safety, since upon burning they release zero CO 2 . [16] Table 1 lists different types of biofuels presently used, which are either in the liquid form or gaseous form. ...
Microbes have been exploited to produce a variety of high-value products such as enzymes, proteins, antibiotics, vitamins, etc. Use of oleaginous microorganisms for production of lipids (commonly called as single cell oils) commenced during the eighteenth century in Germany. Microbial lipids containing special fatty acids such as gamma-linolenic acid, arachidonic acid and docosahexaenoic acid are popularized and are now being produced in a large scale as neutraceuticals and food additives. In the past decade, microbial lipids have been considered as a promising feedstock for biodiesel production due to the contemporary issues on climate change, renewable energy and food security. Recently, various cheap raw materials and biowastes have been explored for economic microbial lipid production, which is considered as a solution to reduce biodiesel production cost and to achieve sustainable management of biowastes. Thus, microbial lipids produced from renewable biomass and biowastes as a second-generation biodiesel feedstock are a promising alternative for vegetable oils. In this review historical development of microbial lipids, biochemistry of lipid accumulation by oleaginous microorganisms, lipid production from various biowastes and renewable materials and cultivation methodologies are reviewed. Microbial lipids as a biodiesel feedstock are also reviewed and discussed.
... Nutrient markets and availabilities are determined by the raw materials used to create them and the current production processes. For instance, nitrogen fertilizers depend on fossil natural gas reserves for production [2], which increases their environmental burden. As the world considers biofuel production, natural gas production is expected to peak in 2035 and this could have serious implications on any biofuel that relies on man-made fertilizers [3]. ...
Biofuels from microalgae are currently the subject of many research projects to determine their feasibility as a replacement for fossil fuels. In order to be a successful candidate, there must be enough fertilizers available to support large scale production. Commercial fertilizers are available for biofuel production from the world fertilizer surplus, but due to nitrogen and phosphorus future production limitations, biofuels would ideally not use any of these resources to be a long term sustainable fuel. Nitrogen, phosphorus and potassium requirements were determined for two algal species, Chlorella and Nannochloropsis, to produce 19 billion l per year (BLPY). At this scale, both algal species would use 32–49%, 32–49% and less than 1% of the world surplus values of nitrogen, phosphorus and potassium, respectively. Nutrient recycling options and alternative sources of nutrients were evaluated to determine their potential contribution of lowering the synthetic fertilizer requirement. Results show that all of the recycling scenarios reduce the nutrient requirements, but catalytic hydrothermal gasification has the largest reduction of 95% of the nitrogen and 90% of the phosphorus. Contributions from all alternative sources can also provide only 5% or less of the required nitrogen when produced in the gulf region. For phosphorus in the same region, poultry concentrated animal feeding operations can provide up to 28% of the requirement of Chlorella. To find the least amount of nitrogen that may be used, catalytic hydrothermal gasification was combined with all of the alternative nutrients available in the gulf region. The maximum amount of biofuels that could be produced in this location without using any synthetic fertilizers is 50 ± 20 BLPY from Chlorella and 45 ± 19 BLPY from Nannochloropsis. This study shows that the nutrient requirement for biofuel production from microalgae will not be a limitation if recycling methods within the process chain and alternative sources of nutrients are utilized.
... Some of these negative studies (e.g., Clarens et al., 21 #7 in Table 1) resulted in a great deal of publicity, with some criticism by algae biofuel proponents. Another recent publication (Pfromm et al. 2010 22 , not in Table 1) was quoted in the press as concluding that ''algae biodiesel production is 'physically impossible'.'' However, what was actually claimed was that using fossil power plant flue gas CO 2 was not truly 'sustainable,'' which is true by definition and requires no analysis. ...
... The sustainability of harvesting technologies is sometimes limited by the amount of energy requiredTable 2 Properties that affect the cost of algal lipid and values set for the moderate condition reference state. [106] 0.22 [107] 0.5 [9] 0.5–1.1 [66] 0.7 [10] 0.2–1.6 [14] 0.26–5 [108] C Electricity , the cost of electricity. ...
Among the most formidable challenges to algal biofuels is the ability to harvest algae and extract intracellular lipids at low cost and with a positive energy balance. In this monograph, we construct two paradigms that contrast energy requirements and costs of conventional and cutting-edge Harvesting and Extraction (H&E) technologies. By application of the parity criterion and the moderate condition reference state, an energy–cost paradigm is created that allows 1st stage harvesting technologies to be compared with easy reference to the National Alliance for Advanced Biofuels and Bioproducts (NAABB) target of $0.013/gallon of gasoline equivalent (GGE) and to the U.S. DOE's Bioenergy Technologies Office 2022 cost metrics. Drawing from the moderate condition reference state, a concentration-dependency paradigm is developed for extraction technologies, making easier comparison to the National Algal Biofuels Technology Roadmap (NABTR) target of less than 10% total energy. This monograph identifies cost-bearing factors for a variety of H&E technologies, describes a design basis for ultrasonic harvesters, and provides a framework to measure future technological advancements toward reducing H&E costs. Lastly, we show that ultrasonic harvesters and extractors are uniquely capable of meeting both NAABB and NABTR targets. Ultrasonic technologies require further development and scale-up before they can achieve low-cost performance at industrially relevant scales. However, the advancement of this technology would greatly reduce H&E costs and accelerate the commercial viability of algae-based biofuels.
... Many parameters can influence the sustainability and economic performance of growing microalgae for biodiesel and biomass, in particular: cultivation area, lipid content and productivity, biomass productivity, efficiency of the process units and selling prices of the microalgae oil and extracted biomass (Campbell et al., 2011;Pfromm et al., 2011;Delrue et al., 2012). ...
... Life cycle assessment (LCA) is a compilation and evaluation of the inputs and outputs and the potential environmental impacts of a product system throughout its life cycle (Pfromm et al., 2011). The outcome of LCA of microalgae-based biodiesel production varies with different culture systems, and the different methods used for biomass harvest and oil refinery (Frank et al., 2013;Resurreccion et al., 2012). ...
Abstract Algal biofuel has become an attractive alternative of petroleum-based fuels in the past decade. Microalgae have been proposed as a feedstock to produce biodiesel, since they are capable of mitigating CO2 emission and accumulating lipids with high productivity. This article is an overview of the updated status of biofuels, especially biodiesel production from microalgae including fundamental research, culture selection and engineering process development; it summarizes research on mathematical and life cycle modeling on algae growth and biomass production; and it updates global efforts of research and development and commercialization attempts. The major challenges are also discussed.
... With regards to the actual raw material and product portfolio, most of the studies related to biorefinery supply chain networks focus on specific biofuel productions, either to determine the sugar-, starch-or lignocellulosic-based bioethanol production (Corsano, Vecchietti, & Montagna, 2011), or oil or fat-based biodiesel production (Andersen, Iturmendi, Espinosa, & Diaz, 2012), or to determine which technology from among the ones proposed in the literature (biochemical, thermochemical, thermo-biochemical) is preferred, and where to locate the biorefineries (Marvin, Schmidt, Benjaafar, Tiffany, & Daoutidis, 2012). Recently, other biofuels have also been considered, mainly derived from lignocellulosic raw materials like Fischer-Tropsch (FT)-diesel, hybrid FT-based fuels (Baliban, Elia, Weekman, & Floudas, 2012;Martín & Grossmann, 2011a;van Vliet, Faaij, & Turkenburg, 2009), hydrogen (Almansoori & Shah, 2009;Martín & Grossmann, 2011b;Tock & Maréchal, 2012), and thirdgeneration algae-based diesel (Cheng, Lu, Gao, & Wu, 2009;Martín & Grossmann, 2012;Pfromm, Amanor-Boadu, & Nelson, 2011;Scott et al., 2010). ...
... The algal biofuels industry cannot depend on the same regional water resources and sources of macronutrients (N, P) that are required for conventional agriculture (Clarens et al., 2010;Handler et al., 2012;Pfromm et al., 2011). The use of recycled wastewater or other impaired water resources can increase the sustainability of algal biodiesel production (Handler et al., 2012;Macova et al., 2011), although not without limit. ...
... Methanogenic Archea (prokaryotic cells similar to bacteria) produce methane from various sources including waste water, and animal and municipal waste (Thauer et al., 2008). Algae can be used to produce biodiesel directly from sunlight, but this technology also is still not fully developed (Scott et al., 2010;Krohn et al., 2011;Patil et al., 2011;Pfromm et al., 2011). ...
For resaons of economy, this document is produced in a limited number of copies. Delegates and observers are kindly requested to bring their copies to meetings and to refrain from asking for additional copies, unless strictly necessary. The documents for this meeting are available on Internet at: 7 This document has been prepared at the request of the Secretariat of the FAO Commission on Genetic Resources for Food and Agriculture, as a contribution to the crosssectoral theme, Consideration of scoping study on climate change and genetic resources for food and agriculture, which the Commission will consider at its Thirteenth Regular Session. The content of this document is entirely the responsibility of the authors, and does not necessarily represent the views of the FAO or its Members.
Production of alternative fuels from microalgae is a promising trend, as it does not require significant land areas. However, modern technologies of cultivation and production do not allow making this process cost-effective. At the same time, known methods of removing biogenic elements from wastewater are not always environmentally safe. The urgent task is to find new methods and technologies. The aim of the study is to demonstrate the possible economic efficiency and environmental safety of the combination of wastewater treatment from nitrogen and phosphorus compounds with the simultaneous cultivation of microalgae for the production of biofuels and biofertilizers. The object of research is the processes of cultivation of mycoalgae, as well as the production of biofuels and biofertilizers. The subject of the research is the economic efficiency and environmental safety of these processes. It is shown that the combination of purification processes with production can not only achieve economic efficiency but also reduce the factor of atmospheric pollution by carbon dioxide by 5.36%, as well as factors of pollution of the hydrosphere: phosphates by 89.5%, ammonium nitrogen by 94.4%, and nitrates by 70.7%.KeywordsAlternative biofuelMicroalgaeBiofertilizerBiogenic elementCarbon dioxidePhosphatesNitratesAmmonium nitrogenEnvironmental safetyEconomic efficiency
Biorefineries are becoming increasingly important in providing sustainable routes for chemical industry processes. The establishment of bio-economic models, based on biorefineries for the creation of innovative products with high added value, such as biochemicals and bioplastics, allows the development of “green chemistry” methods in synergy with traditional chemistry. This reduces the heavy dependence on imports and assists the development of economically and environmentally sustainable production processes, that accommodate the huge investments, research and innovation efforts.
This book explores the most effective or promising catalytic processes for the conversion of biobased components into high added value products, as platform chemicals and intermediates. With a focus on heterogeneous catalysis, this book is ideal for researchers working in catalysis and in green chemistry.
Growing microalgae on a commercial scale for food production has a substantial tradition, dating back to the 1950s. For this purpose, autotrophic microalgae such as Spirulina and Chlorella are grown, usually in open ponds. Autotrophic microalgae, which convert solar energy into biomass by photosynthesis, have also been proposed as a source of biofuels, especially as a source of lipids (fatty acids, oil) for biodiesel. This chapter discusses the production of liquid biofuels from autotrophic microalgae than from lipids. It focuses on the better researched autotrophic microalgal lipid-based liquid biofuels, especially biodiesel. An energetic criterion for suitable energy sources is discussed. The chapter also outlines life cycle assessment (LCA) that can address the energetic and environmental performance of biofuels. Thereafter, it considers life cycle energetic inputs and outputs and the life cycle emissions of greenhouse gases and pollutants.
The microalgae oil obtained from chlorella protothecoides was converted to microalgae oil methyl ester using transesterification process. The physical and chemical properties of microalgae oil and microalgae oil methyl ester were tested and it was observed that chlorella protothecoides oil and microalgae oil methyl ester can meet the ASTM standards for the characteristics tested. In this research work performance, combustion and emission parameters were analyzed on a Kirloskar single cylinder direct injection compression ignition water cooled diesel engine having capacity 5.2 kW fueled with diesel, microalgae oil and microalgae oil methyl ester. The engine showed the reduction in emission of CO, UBHC, NOx and Smoke Opacity as compared to those of diesel when fueled with microalgae oil and microalgae oil methyl ester. A general trend of decrease in the brake thermal efficiency with the use of microalgae oil and microalgae oil methyl ester was observed.
Simultaneous extraction and transesterification of oil from rape seeds using a mineral diesel and butanol mixture have been performed to obtain a mineral diesel and biodiesel mixture that is currently used as fuel. Lipozyme RM IM is an enzyme preparation well known for having major catalytic activity during oil transesterification. The response surface method was used to optimize the process of simultaneous oil extraction and transesterification. We aimed to not only extract the maximum amount of oil from rape seeds, but also to transesterify the whole amount using butanol. We determined that the optimum conditions for simultaneous oil extraction and transesterification using butanol were as follows: molar butanol to oil ratio — 31:1, amount of ferment preparation Lipozyme RM IM — 5.2%, duration — 19.6 h, temperature — 40 °C, and mineral diesel to oil ratio (w/w) — 9:1.
Microalgae continue to be of great interest as a promising class of biofuel feedstock, with the potential for contributing to liquid transportation fuel supplipes while reducing GHG emissions and dependence on imported petroleum through the displacement of petroleum-based fuel and chemical product usage. However, to significantly contribute to fuel supplies will require that algal biofuels be capable of scaling up to large aggregated quantities of biomass and fuel feedstock production that necessarily impose huge demands for land, water, energy, supplemental CO2 and other key nutrients such as nitrogen and phosphorus. The resulting resource requirements will also impose constraints on the level of production scale-up that can be sustainably supported. This paper provides a high-level review of the current status and future prospects for these key resource demand and constraint challenges for the scale-up of autotrophic microalgal biofuel production. Emphasis is placed on the USA, although the issues are generally relevant globally.
The motivation for this research was to determine the influence of public policies on economic feasibility of producing algal biodiesel in a system that produced all its energy needs internally. To achieve this, a steady-state mass balance/unit operation system was modeled first. Open raceway technology was assumed for the production of algal feedstock, and the residual biomass after oil extraction was assumed fermented to produce ethanol for the transesterification process. The project assumed the production of 50 million gallons of biodiesel per year and using about 14% of the diesel output to supplement internal energy requirements. It sold the remainder biodiesel and ethanol as pure biofuels to maximize the rents from the renewable fuel standards quota system. Assuming a peak daily yield of 500 kg algal biomass (dry basis)/ha, the results show that production of algal biodiesel under the foregoing constraints is only economically feasible with direct and indirect public policy intervention. For example, the renewable fuel standards' tracking RIN (Renewable fuel Identification Number) system provides a treasury-neutral value for biofuel producers as does the reinstatement of the renewable fuel tax credit. Additionally, the capital costs of an integrated system are such that some form of capital cost grant from the government would support the economic feasibility of the algal biodiesel production.
Commercial cultivation of autotrophic microalgae for food production dates back to the 1950s. Autotrophic microalgae have also been proposed as a source for lipid‐based liquid biofuels. As yet, there is no commercial production of such biofuels and estimated near‐term prices are far in excess of fossil fuel prices and prices of biofuels based on terrestrial food oil crops. Future costs of autotrophic microalgal lipid‐based biofuels are very uncertain. The energetic return of energy investment in liquid autotrophic microalgal biofuels is below a factor 5, even if optimistic assumptions are made about future technologies. Available studies do not allow for firm estimates of life cycle greenhouse gas emissions of autotrophic microalgal lipid‐based biofuels. Apart from greenhouse gases, life cycle pollutant emissions of autotrophic microalgal biodiesel may well be more of an environmental burden than the life cycle pollutant emissions linked to fossil diesel or biofuels based on canola or switchgrass. Whether the prospects for, and performance of, lipid‐based biofuels from autotrophic microalgae in the more distant future will much improve appears to be largely dependent on breakthroughs in production technology which may, or may not, occur.
This article is categorized under: Bioenergy > Science and Materials
Commercial buildings and institutions are generally cooling-dominated and therefore reject more heat to a ground- loop heat exchanger than they extract over the annual cycle. This paper describes the development, validation, and use of a design and simulation tool for modeling the performance of a shallow pond as a supplemental heat rejecter in ground- source heat pump systems. The model has been developed in the TRNSYS modeling environment and can therefore be coupled to other GSHP system component models for short time step (hourly or less) system analyses. The model has been validated by comparing simulation results to experimental data collected from two test ponds. The solution scheme involves a lumped-capacitance approach, and the resulting first-order differential equation describing the overall energy balance on the pond is solved numerically. An example appli- cation is presented to demonstrate the use of the model as well as the viability of the use of shallow ponds as supplemental heat rejecters in GSHP systems. Through this example, it is shown that ground-loop heat exchanger size can be signifi- cantly decreased by incorporating a shallow pond into a GSHP system.
Sustainable use of groundwater must ensure not only that the future resource is not threatened by overuse, but also that natural environments that depend on the resource, such as stream baseflows, riparian vegetation, aquatic ecosystems, and wetlands are protected. To properly manage groundwater resources, accurate information about the inputs (recharge) and outputs (pumpage and natural discharge) within each groundwater basin is needed so that the long-term behavior of the aquifer and its sustainable yield can be estimated or reassessed. As a first step towards this effort, this work highlights some key groundwater recharge studies in the Kansas High Plains at different scales, such as regional soil-water budget and groundwater modeling studies, county-scale groundwater recharge studies, as well as field-experimental local studies, including some original new findings, with an emphasis on assumptions and limitations as well as on environmental factors affecting recharge processes. The general impact of irrigation and cultivation on recharge is to appreciably increase the amount of recharge, and in many cases to exceed precipitation as the predominant source of recharge. The imbalance between the water input (recharge) to the High Plains aquifer and the output (pumpage and stream baseflows primarily) is shown to be severe, and responses to stabilize the system by reducing water use, increasing irrigation efficiency, adopting water-saving land-use practices, and other measures are outlined. Finally, the basic steps necessary to move towards sustainable use of groundwater in the High Plains are delineated, such as improving the knowledge base, reporting and providing access to information, furthering public education, as well as promoting better understanding of the publics attitudinal motivations; adopting the ecosystem and adaptive management approaches to managing groundwater; further improving water efficiency; exploiting the full potential of dryland and biosaline agriculture; and adopting a goal of long-term sustainable use.El uso sostenible de aguas subterrneas debe garantizar tanto que el recurso futuro no est amenazado por sobreutilizacin como que los ambientes naturales dependientes del recurso sean protegidos (ie el flujo base de los arroyos, la vegetacin ripariana, los ecosistemas acuticos y los pantanos). El manejo adecuado de los recursos de aguas subterrneas requiere informacin precisa con respecto a los influjos (recarga) y descargas (bombeo y descarga natural) en cada cuenca de aguas subterrneas de tal manera que se pueda estimar o reevaluar el comportamiento de largo plazo del acufero y su tasa de sotenibilidad. En un primer paso hacia esta meta, este trabajo destaca algunos estudios claves de recarga de aguas subterrneas en las llanuras altas de Kansas. Dichos estudios se concentran en diferentes escalas: estudios regionales del presupuesto para aguas del suelo y modelos de aguas subterrneas, estudios de recarga de aguas subterrneas a nivel provincial y estudios locales experimentales de terrenos que incluyen algunos interesantes descubrimientos nuevos. Estas investigaciones comparten el nfasis en los presupuestos de partida y las limitaciones as como en los factores ambientales que afectan los procesos de recarga. El impacto general de las irrigaciones y cultivos sobre la recarga es un obvio incremento en el monto de recarga y en muchos casos excede a la precipitacin como la fuente principal de recarga. Se puede observar que el desequilibrio entre el influjo de agua (recarga) del acufero de las llanuras altas y la descarga (bombeo y flujos base de los arroyos principalmente) es severo. Asimismo, se describen las respuestas para estabilizar el sistema a travs de la reduccin del uso de agua por medio del incremento de la eficiencia de las irrigaciones y de la adopcin de las prcticas de ahorro de agua y del uso de tierras as como otras medidas adicionales. Finalmente se describen los pasos bsicos necesarios para evolucionar hacia el uso sostenible de las aguas subterrneas en las llanuras altas de Kansas. Estos pasos estn constituidos por una mejora del conocimiento base, comunicar y proporcionar fcil acceso a la informacin, mejorar el conocimiento pblico general as como promover un mejor entendimiento de las motivaciones para las actitudes de la comunidad, adoptar los enfoques administrativos de ecosistemas y administracin adaptable en el manejo de las aguas subterrneas, continuar las mejoras del uso eficiente del agua, explotar el potencial de la agricultura de terrenos ridos y biosalina y adoptar como meta el uso sostenible a largo plazo.Lutilisation durable de leau souterraine doit permettre non seulement que la prennit de leau ne soit pas menace, mais aussi que les environnements naturels qui dpendent de cette ressource, tels que la vgtation riveraine, les cosystemes aquatiques et les milieux humides, soient protgs. Afin dassurer une gestion approprie des ressources en eau souterraine, une information prcise concernant les entres (recharge) et les sorties (dcharge naturelle et pompage) deau dans chacun des bassins est ncessaire afin que le comportement long terme de laquifre et le taux de pompage durable puissent tre estims. En guise dinitiative, ce travail illustre certaines tudes cl concernant la recharge de leau souterraine plusieurs chelles dans les hautes plaines du Kansas. Ces tudes comprennent le bilan sol-eau et la modlisation numrique lchelle rgionale, ltude de la recharge des nappes souterraines lchelle du comt, des tudes exprimentales petite chelle et certaines dcouvertes originales. Lors de la prsentation de ces tudes, lemphase est porte sur les hypothses et limitations ainsi que sur les facteurs environmentaux qui affectent les processus de recharge. En gnral, les effets de lirrigation et de lagriculture sur la recharge sont daugmenter considrablement le taux de recharge, et dans plusieurs cas, dexcder les prcipitations comme principale source de recharge. Le dsquilibre entre les intrants deau (recharge) et entrants (pompage et coulement de base dans les rivires) dans laquifre des hautes plaines est trs important. Les rsultats des efforts de stabilisation du systme aquifre en diminuant lutilisation deau, en amliorant lefficacit des techniques dirrigation, en adoptant des pratiques dutilisation du territoire qui rduisent lutilisation deau et en adoptant certaines autres mesures sont prsents. Enfin, les tapes de base ncessaires afin datteindre une utilisation durable de leau souterraine dans les hautes plaines sontexposes. Elles comprennent lamlioration des connaissance de base, lapromotion dune meilleure comprhension de la motivation et de lattitudedu public, ladoption dune approche de gestion de leau souterraineadaptable et base sur les cosystmes, lamlioration de lefficacitdutilisation de leau, lexploitation du plein potentiel de lagriculturebiosaline et en milieu aride, et ladoption dun objectif pourlutilisation durable long terme.
Interest in algae as a feedstock for biofuel production has risen in recent years, due to projections that algae can produce
lipids (oil) at a rate significantly higher than agriculture-based feedstocks. Current research and development of enclosed
photobioreactors for commercial-scale algal oil production is directed towards pushing the upper limit of productivity beyond
that of open ponds. So far, most of this development is in a prototype stage, so working production metrics for a commercial-scale
algal biofuel system are still unknown, and projections are largely based on small-scale experimental data. Given this research
climate, a methodical analysis of a maximum algal oil production rate from a theoretical perspective will be useful to the
emerging industry for understanding the upper limits that will bound the production capabilities of new designs. This paper
presents a theoretical approach to calculating an absolute upper limit to algal production based on physical laws and assumptions
of perfect efficiencies. In addition, it presents a best case approach that represents an optimistic target for production
based on realistic efficiencies and is calculated for six global sites. The theoretical maximum was found to be 354,000L·ha−1·year−1 (38,000gal·ac−1·year−1) of unrefined oil, while the best cases examined in this report range from 40,700–53,200L·ha−1·year−1 (4,350–5,700gal·ac−1·year−1) of unrefined oil.
KeywordsAlgae-Biofuels-Theoretical yield-Oil production-Second-generation feedstock
Quantifying the environmental impact of chemical technologies and products, and comparing alternative products and technologies in terms of their "greenness" is a challenging task. In order to characterise various aspects of a complex phenomenon, a number of different indicators are selected into a metric. This book outlines fundamental developments in chemistry and chemical technology that have led to the development of green chemistry, green chemical technology, and sustainable chemical technology concepts, and provide a foundation for the development of the corresponding metrics. It includes different approaches to metrics, and case study examples of their applications, and problems in practice. Green Chemistry Metrics is aimed at graduate students and researchers, practitioners and environmental managers in industry, metrics developers, and governmental agencies and NGOs in the area of environmental protection and sustainability. The main focus will be on chemical processes, however the book will be relevant to other industry sectors such as energy, electronics, healthcare, food and consumer products.
IntroductionMethods
Case studiesDiscussionConclusions
AcknowledgementsReferences
This introduction to chemical processes lays the foundation for a chemical engineering curriculum. It shows beginning students how to apply engineering techniques to the solution of process-related problems by breaking each problem down into individual component parts, defining the relationship between them, and reuniting them in a single solution. Providing detailed practical examples with ever problem, and self-test questions at the end of each chapter, it uses predominantly SI units in its coverage of theoretical components of an engineering calculation, processes and process variables, fundamentals of material balances, single and multiphase systems, energy and energy balances, and balance on nonreactive processes.
This report presents the findings from a study of the life cycle inventories for petroleum diesel and biodiesel. It presents information on raw materials extracted from the environment, energy resources consumed, and air, water, and solid waste emissions generated. Biodiesel is a renewable diesel fuel substitute. It can be made from a variety of natural oils and fats. Biodiesel is made by chemically combining any natural oil or fat with an alcohol such as methanol or ethanol. Methanol has been the most commonly used alcohol in the commercial production of biodiesel. In Europe, biodiesel is widely available in both its neat form (100% biodiesel, also known as B1OO) and in blends with petroleum diesel. European biodiesel is made predominantly from rapeseed oil (a cousin of canola oil). In the United States, initial interest in producing and using biodiesel has focused on the use of soybean oil as the primary feedstock mainly because the United States is the largest producer of soybean oil in the world. 170 figs., 148 tabs.
IntroductionThe LCA methodologyApplication of LCA in process development - a case studyCombination of LCA or SLCA and optimisationSLCA and optimisation - a case studyConclusion
References
Higher crude-oil prices, increases in energy imports, concerns about petroleum supplies, and greater recognition of environmental consequences of fossil fuels have spurred a search for alternative sources of fuel. In the aspect of choosing an appropriate source for a long-term development, it is necessary to decide which is the most sustainable. This article describes a systematic method based on Analytical Hierarchical Process technique to compare biodiesel feedstock alternatives on technical, economical, and sustainable aspects throughout life cycles of biodiesel production. Five biodiesel feedstocks which are jatropha, algae, palm oil, rapeseed, and soybean are taken into consideration in a quantified evaluation. Among these alternatives and with a recommended scoring structure, biodiesel from algae is shown in the calculation results to be the highest ranking substitute for diesel fuel due to its overall better performance in the aspects of environment, economical, safety, raw material performance, and fuel performance. © 2009 American Institute of Chemical Engineers Environ Prog, 2009
ABSTRACTA life cycle assessment (LCA) case study was conducted on the processing of soybeans to soybean oil. Three stages of soybean oil processing are studied in detail: preprocessing, extraction and separation, and postprocessing. For extraction, hexane (current industrial process) and supercritical CO2 (research and development [R & D] laboratory-scale process) methods are compared in detail. The initial life cycle comparison found that the laboratory-scale CO2 system was not as good in life cycle impacts as the hexane system. However, reasonable engineering improvements typical of scale-up practices would make the CO2 technology better than hexane and eliminate the hexane emissions. Utilization of membrane techniques to separate the small molecular CO2 from the soybean oil hydrocarbon appears to be a much better R & D direction for development. This article illustrates the ability to use life cycle as an aid to R & D to select more advantageous directions for process improvement.
It is frequently claimed that green algae are intrinsically more productive, often by orders of magnitude, than higher plants
commonly grown as crops for food. There is no firm evidence for this belief. On the contrary, there is much experience which
shows that algae are not more but less productive. Under optimal conditions, all green organisms photosynthesize at the same
rate in low light and, whilst commonly cultivated ‘sun’ species show some differences in rate in full light, these do not
translate into widely different rates of accumulation of biomass. Accordingly, irrespective of crop, one acre of land, pond
or bioreactor, can annually yield about enough biomass to fuel one motor vehicle or meet the calorific requirement of several
people. This amount of biomass is not sufficient to make other than a very small contribution to our present road transport
requirements and yet contributes significantly to global food shortages and rising prices. Reliable evidence also suggests
that, if all of the inputs are taken into account, the net energy gain of liquid biofuels, derived either from algae or terrestrial
crops, is either very modest or non-existent and will therefore bring about little or no sparing of carbon dioxide emissions.
The energy balance of a lake with an area of approximately 46000 ha and a depth of 3 m has been estimated from simple weather data measured along the perimeter of the lake. These measurements are dry-bulb temperature and relative humidity, both at 1.5-m height, windspeed at 3-m height and sunshine duration. The estimated energy balance values were compared with the values computed from the measurements at the station situated at the centre of the lake. At this station, net radiation, water temperature, dry-bulb and wet-bulb temperature at a height of 2 m were measured. It is possible to estimate the daily evaporation from the lake with an error of 0.6 mm day–1, if the location of measurement is downwind from the lake.
Fermentation-derived butanol is a possible alternative to ethanol as a fungible biomass-based liquid transportation fuel. We compare the fermentation-based production of n-butanol vs. ethanol from corn or switchgrass through the liquid fuel yield in terms of the lower heating value (LHV). Industrial scale data on fermentation to n-butanol (ABE fermentation) or ethanol (yeast) establishes a baseline at this time, and puts recent advances in fermentation to butanol in perspective. A dynamic simulation demonstrates the technical, economic and policy implications.The energy yield of n-butanol is about half that of ethanol from corn or switchgrass using current ABE technology. This is a serious disadvantage for n-butanol since feedstock costs are a significant portion of the fuel price. Low yield increases n-butanol's life-cycle greenhouse gas emission for the same amount of LHV compared to ethanol. A given fermenter volume can produce only about one quarter of the LHV as n-butanol per unit time compared to ethanol. This increases capital costs. The sometimes touted advantage of n-butanol being more compatible with existing pipelines is, according to our techno-economic simulations insufficient to alter the conclusion because of the capital costs to connect plants via pipeline.
Process modeling is an important task during many process engineering activities such as steady-state and dynamic process simulation, process synthesis or control system design and implementation. The demand for models of varying detail is expected to steadily increase in the future due to advances in model-based process engineering methodologies. Computer assistance to support the development and implementation of adequate and transparent models is indispensable to minimize the engineering effort. The state of the art and current trends in computer-aided modeling are presented in this contribution which is intended to serve as a survey and a tutorial at the same time.
This paper provides an analysis of the potential environmental impacts of biodiesel production from microalgae. High production yields of microalgae have called forth interest of economic and scientific actors but it is still unclear whether the production of biodiesel is environmentally interesting and which transformation steps need further adjustment and optimization. A comparative LCA study of a virtual facility has been undertaken to assessthe energetic balance and the potential environmental impacts of the whole process chain, from the biomass production to the biodiesel combustion. Two different culture conditions, nominal fertilizing or nitrogen starvation, as well as two different extraction options, dry or wet extraction, have been tested. The best scenario has been compared to first generation biodiesel and oil diesel. The outcome confirms the potential of microalgae as an energy source but highlights the imperative necessity of decreasing the energy and fertilizer consumption. Therefore control of nitrogen stress during the culture and optimization of wet extraction seem to be valuable options. This study also emphasizes the potential of anaerobic digestion of oilcakes as a way to reduce external energy demand and to recycle a part of the mineral fertilizers.
Biofuels have been proposed as an ecologically benign alternative to fossil fuels. There is, however, considerable uncertainty in the scientific literature about their ecological benefit. Here, we review studies that apply life-cycle analysis (LCA), a computational tool for assessing the efficiency and greenhouse gas (GHG) impact of energy systems, to biofuel feedstocks. Published values for energy efficiency and GHG differ significantly even for an individual species, and we identify three major sources of variation in these LCA results. By providing new information on biogeochemistry and plant physiology, ecologists and plant scientists can increase the accuracy of LCA for biofuel production systems.
Photosynthesis is the source of our food and fiber. Increasing world population, economic development, and diminishing land resources forecast that a doubling of productivity is critical in meeting agricultural demand before the end of this century. A starting point for evaluating the global potential to meet this goal is establishing the maximum efficiency of photosynthetic solar energy conversion. The potential efficiency of each step of the photosynthetic process from light capture to carbohydrate synthesis is examined. This reveals the maximum conversion efficiency of solar energy to biomass is 4.6% for C3 photosynthesis at 30 degrees C and today's 380 ppm atmospheric [CO2], but 6% for C4 photosynthesis. This advantage over C3 will disappear as atmospheric [CO2] nears 700 ppm.
Microalgae represent an exceptionally diverse but highly specialized group of micro-organisms adapted to various ecological habitats. Many microalgae have the ability to produce substantial amounts (e.g. 20-50% dry cell weight) of triacylglycerols (TAG) as a storage lipid under photo-oxidative stress or other adverse environmental conditions. Fatty acids, the building blocks for TAGs and all other cellular lipids, are synthesized in the chloroplast using a single set of enzymes, of which acetyl CoA carboxylase (ACCase) is key in regulating fatty acid synthesis rates. However, the expression of genes involved in fatty acid synthesis is poorly understood in microalgae. Synthesis and sequestration of TAG into cytosolic lipid bodies appear to be a protective mechanism by which algal cells cope with stress conditions, but little is known about regulation of TAG formation at the molecular and cellular level. While the concept of using microalgae as an alternative and renewable source of lipid-rich biomass feedstock for biofuels has been explored over the past few decades, a scalable, commercially viable system has yet to emerge. Today, the production of algal oil is primarily confined to high-value specialty oils with nutritional value, rather than commodity oils for biofuel. This review provides a brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization.
Algal Culture, From Laboratory to Pilot Plant Production of methanol
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A Look Back at the US Department of Energy's Aquatic Species Program – Biodiesel from Algae Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus
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Production of Methanol
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Cheng, W.-H., Kung, H.H., 1994. Production of Methanol. in: W.-H. Cheng, H.H. Kung (Eds.),
Methanol Production and Use. Marcel Dekker Inc., New York.
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A model for simulating the performance of a shallow pond as a supplemental heat rejecter with closed-loop ground-source heat pump systems American Society of Heating, Refrigerating and Air-Conditioning Transactions Life-cycle analysis and the ecology of biofuels
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Methanol Production and Use
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Cheng, W.-H., Kung, H.H., 1994. Production of Methanol. in: W.-H. Cheng, H.H. Kung (Eds.),
Methanol Production and Use. Marcel Dekker Inc., New York.
Nonsterile Large-Scale Culture of Chlorella in Greenhouse and Open Air
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