A series of high moisture content biomass have been processed by hydrothermal carbonisation (HTC) in a batch reactor at two temperatures (200°C and 250°C). The feedstocks processed include food ...waste, secondary sewage sludge, AD press cake, microalgae, macroalgae and a fibre derived from municipal derived wastes. In addition, three lignocellulosic biomass including miscanthus, willow and oak wood have been processed under identical conditions. The yields and properties of the resulting hydrochars including their HHV, CHNS, mineral content and ash fusibility properties have been determined and compared with their starting biomass. Typical char yields for lignocellulosic material range between 58 and 70wt% at 200°C and reduce to 40–46wt% at 250°C. The behaviour and mass balance is however very feedstock dependent and the higher lignin biomass produce higher yields of hydrochar. There is a significant upgrading of the energy density of the hydrochars with calculated HHV ranging from typically 24MJkg−1 at 200°C to 28–31MJkg−1 at 250°C for lignocellulosic material. The exception is for sewage sludge and AD press cake which result in a significant solubilisation of organic matter. A significant removal of alkali metals is observed and this in turn changes the ash chemistry upon combustion. This change in ash chemistry has been shown to change the ash melting behaviour and the hemisphere temperatures (oxidising conditions) were seen to increase substantially. A number of predictive slagging and fouling indices have been used to evaluate the influence of the ash chemistry on the fuel combustion behaviour and this combined with the ash fusion testing has shown that HTC reduces the potential fouling and slagging in some of the resulting hydrochars if combusted.
Environmental, economic and political pressures have driven the interest towards the search of sustainable feedstock for biofuel production. At present, macroalgae (green, brown and red marine ...seaweed) is getting growing consideration as an alternative resource for sustainable biomass to produce biofuels, biochemical and food. The unique chemical composition and wide variation in the availability create various opportunities and also challenges for bio-based energy production. Recently, numerous studies have taken place in the exploitation of seaweed as carbon sources for the bioethanol production. Thus, this paper attempts to highlight the characteristics, processing techniques and potential applications of the seaweed. The present review also focuses on recent innovative approaches for the sustainable production of bioenergy from seaweed.
The current issues of the depletion of fossil fuels reserve and environmental changes have increased the concern for the hunt of sustainable renewable energy for the future generations. Biofuels ...emerged as a promising viable alternative to replace the existing fossil fuels. Among these, bioethanol outstands due to its ability to substitute gasoline. However, the major challenge in bioethanol industry is the need to discover a suitable feedstock together with an environmentally friendly approach and an economically feasible process of production. The first generation and second generation bioethanol appeared unsustainable due to its impact on food security as well as inflated production process. These problems and concerns have directed the search for the third generation bioethanol (TGB) feedstock from marine algae. The integration of algae (microalgae and macroalgae) as a sustainable feedstock for bioethanol has gained worldwide attention in terms of food security and environmental impact. The research on algal utilization in bioethanol has increased in recent years and is expected to become the major drives in bioethanol industry. Therefore, the potential and prospects of the third generation bioethanol feedstock are being highlighted in this review. An insight into the current hydrolysis and fermentation technologies on algal conversion together with the economics and viability of the process are also accounted. This review can be crucial in providing ideas for the future studies that can be implemented in the commercialization of bioethanol from the third generation feedstock.
•Fatty acid contents and profiles of 61 southern Australian seaweed species.•Identification of species with high proportion of poly unsaturated fatty acids (PUFA).•Fatty acid composition of most ...species rich in essential and long-chain PUFA.•Low n-3/-6 PUFA ratio in majority of species, suitable for food applications.•Results highlight Australian seaweeds as potential resource of PUFA.
To assess the suitability of southern-Australian macroalgae as potential marine resources for fatty acids (FA), and in particular polyunsaturated fatty acids (PUFA), analysis of 61 species, comprising of 11 Chlorophyta, 17 Phaeophyceae (Ochrophyta) and 33 Rhodophyta, was conducted. Total fatty acid (TFA) concentrations varied considerably (between 0.6 and 7.8 in % of dry weight (DW)) between species, with on average the highest concentrations being in the Phaeophyceae, then the Chlorophyta, and with the Rhodophyta recording the lowest average concentrations. Results revealed significant differences in the fatty acid profiles of the three algal groups. Most species exhibit high proportions of PUFA in their fatty acid profile and a low ratio of n-6/n-3 PUFA. These properties highlight the potential for southern-Australian macroalgae to be used for these FA in food, animal feed and nutraceutical applications.
Algae is a very promising source for renewable energy production since it can fix the greenhouse gas (CO2) by photosynthesis and does not compete with the production of food. Compared to microalgae, ...researches on biofuel production from macroalgae in both academia and industry are at infancy for economically efficient and technological solutions. This review provides up to-date knowledge and information on macroalgae-based biofuels, such as biogas, bioethanol, biodiesel and bio-oils respectively obtained from anaerobic digestion, fermentation, transesterification, liquefaction and pyrolysis technique methods. It is concluded that bioethanol and bio-oils from wet macroalgae are more competitive while biodiesel production seems less attractive compared to high lipid content microalgae biomass. Finally, a biorefinery concept based on macroalgae is given.
•A cogeneration system is proposed to convert algae into H2 and power production.•The system consists of drying, gasification, chemical looping, and power generation.•The system is modeled and ...evaluated using Aspen Plus software package.•The relations between the parameters and the performance of the system are obtained.
A cogeneration system is proposed in this study to produce H2 and generate power from brown macroalgae with a high moisture content. The processes used in the cogeneration system consisted of drying, steam gasification, syngas chemical looping (SCL), and power generation. Enhanced process integration technology was utilized to maximize heat recovery in the system by minimizing the destruction of exergy. The SCL system used in this study consisted of a fuel reactor, a steam reactor, and an air reactor. Iron oxide was utilized as the circulating oxygen carrier in the SCL system and was reduced and oxidized during its passage through the SCL reactors. The performance of the cogeneration system was evaluated at different target moisture contents during drying, steam-to-biomass ratios during gasification, and operating pressures in the SCL system by means of process simulation using the Aspen Plus software package. The results of the simulation show that the proposed system had a relatively high total efficiency (about 72%), which consisted of H2 production and power generation efficiencies of about 57% and 15%, respectively.
The objective of this work is to provide a comprehensive study on algal biomass as feedstock for biogas production. Algae-derived biofuels are seen as one of the most promising solutions to mitigate ...climate change and as alternative to fast depleting of fossil fuels and oil reserves. Microalgae and macroalgae underwent an intense academic and industrial research, thanks to their capability to overcome the drawbacks related to the first and second generations of biomass resources. Major advantages of algae are: no competition with food crops for arable land, high growth rates, low fractions of lignin which reduces the need for energy-intensive pretreatment and compatibility with biorefinery approach implementation. However, some disadvantages such as the presence of high water content, seasonal chemical composition and the occurrence of inhibitory phenomena during anaerobic digestion, make algal biofuels not yet economically feasible although they are more environment friendly than fossil fuels.
In this study, an integrated biomass conversion concept of producing liquid biofuels from fresh water macroalgal biomass was investigated. The algal biomass was collected from the Song river, ...Dehradun, Uttarakhand, India and processed under laboratory. 0.650 g dry wt m−2of algal biomass was harvested from the freshwater river. The collected algal biomass contained mainly 2 macroalgae species. Lipid extraction was done by soxhlet extraction method using chloroform: methanol (2:1) as solvent. 18.6% of lipid was obtained from macroalgae biomass. Blends of algae biodiesel with, butanol and diesel fuel (A5B25D70 and A10B30D60) were prepared by Inline blending method on a volume basis. Oil extracted algal biomass was further hydrolyzed for release of fermentable sugar. The theoretical yield of conversion of fermentable sugars to bioethanol was estimated and found to be 61.0%.
•Fresh water macroalgal biomass can be utilized for production of liquid biofuels.•18.6% of lipid was obtained from macroalgal biomass.•Addition of diesel and butanol to algal biodiesel can improve engine performance.•Emission characteristics of CO and NOx can be improved by adding butanol.•Theoretical yield of ethanol was estimated 61.0% from lipid extracted algal biomass.
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•Synergistic effects were existed in both TGA analysis and fixed bed experiment.•Co-pyrolysis of macroalgae and PVC promoted the quality of bio-oils.•Interactions during co-pyrolysis ...decreased the H/C atomic ratio of bio-chars.•A majority of chlorine from EN-PVC blends was trapped in bio-char products.
The present study aimed to investigate synergistic effects on properties of bio-oil/bio-char and transferring regularity of chlorine during co-pyrolysis of macroalgae Enteromorpha clathrata (EN) mixed with different mass percentage of polyvinyl chloride (PVC) (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in a fixed bed reactor at 550 °C. The results showed that the experimental values of bio-oils were 0.43–2.57 wt% lower than the calculated values, while the bio-chars were 1.28–4.93 wt% higher. From the GC–MS analysis of bio-oils, the relative contents of oxygenated and nitrogenated compounds were reduced significantly while those of phenols, aromatic and aliphatic compounds were increased dramatically during co-pyrolysis of EN and PVC. Interaction during co-pyrolysis of EN and PVC decreased the H/C atomic ratio of bio-chars, enhancing the aromatic degree. In addition, the chlorine distribution in bio-chars increased whereas decreased in bio-oils and non-condensable gas with the addition content of PVC increasing. The results showed that a majority of chlorine from EN-PVC blends was trapped in bio-char products, which was favorable to the utilization of bio-oils and friendly to pyrolysis equipment and environment.
Economic and environmental developments in the last decades call for the displacement of fossil fuels to alternative energy sources. Biofuels are considered as a part of the solution for this ...challenge. Sustainable raw materials for the production of transportation biofuels such as biodiesel, biobutanol and bioethanol, can be obtained from algal biomass. In particular, marine macroalgal biomass is a promising feedstock for transportation biofuels because of (the) its fast growth and its potential cultivation on seawater, avoiding competition of resources with conventional agriculture of terrestrial plants used for food. In addition, dissolved inorganic nutrients like nitrogen, phosphorous and carbon are taken up by macroalgae, helping to alleviate eutrophication in seas and oceans. Using biological, chemical and engineering advances in the last decades, technologies to provide cost efficient cultivation, harvesting, extraction and processing of sustainable biofuels have to be elaborated. This paper provides a review of macroalgae based biorefineries with offshore cultivation and consequent biomass conversion into transportation liquid biofuels. We discuss the methods for offshore cultivation, harvesting, and conversion of macroalgae biomass into liquid transportation biofuels. Based on the current information and global experience, we present local perspectives specific for France, Germany, Norway, the Netherlands and Israel on the potential use of Exclusive Economic Zone for transportation biofuels production. Marketable suggestions for future research need to include all stakeholders of a given site for offshore biorefinery development.
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