Supercritical Water Gasification Of Algae

Diversification of our energy supplies – especially in the transport and electricity generation sectors – is required to meet decarbonisation targets. Algae have been identified as suitable alternative feedstocks for third generation biofuels due to their fast growth rates and non-competitiveness with land for food crops. Hydrothermal processing of algae is an appropriate conversion route as it allows the processing of wet feedstock thus removing the energy penalty of drying. In this study, supercritical water gasification was used for (i) the hydrothermal processing of macroalgae for the production of gaseous fuel – mainly hydrogen and methane – and (ii) the upgrading of the process water from hydrothermal liquefaction of microalgae for hydrogen production for biocrude hydrotreating. The supercritical water gasification (SCWG) of the four macroalgae species investigated (Saccharina latissima, Laminaria digitata, Laminaria hyperborea, and Alaria esculenta) produced a gas that mainly consisted of hydrogen, methane and carbon dioxide. Non-catalytic SCWG resulted in hydrogen yields of 3.3-4.2 mol/kg macroalgae and methane yields of 1.6-3.3 mol/kg macroalgae. Catalytic SCWG (using ruthenium) resulted in hydrogen yields of 7.8-10.2 mol/kg macroalgae and methane yields of 4.7-6.4 mol/kg macroalgae. The yield of hydrogen was approximately three times higher when using sodium hydroxide as catalyst (16.3 mol H2 / kg macroalgae) compared to non-catalysed SCWG of L. hyperborea (5.18 mol H2 / kg macroalgae). The energy recovery (an expression of how much chemical energy of the feedstock is recovered in the desired product following hydrothermal processing) was 83% when sodium hydroxide was used as a catalyst, compared to 52% for the non-catalytic SCWG of L. hyperborea. The yield of methane was approximately 2.5 times higher (9.0 mol CH4 kg 1macroalgae) when using ruthenium catalyst compared to the non-catalysed experiment (3.36 mol CH4 / kg macroalgae) and the energy recovery increased by 22% to 74%. The selectivity of methane or hydrogen production during the SCWG of macroalgae can be controlled using ruthenium or sodium hydroxide respectively. Longer hold times and increased reaction temperature favoured methane production when using ruthenium. An increase in catalyst loading had no significant effect on the methane yield. Higher hydrogen yields were obtained through using higher concentrations of sodium hydroxide, lower algal feed concentration and shorter hold times (30 min). Increasing reaction times (>30 min) with a base catalyst (sodium hydroxide) decreased the hydrogen yield. Overall energy recovery was highest at the lowest feed concentrations; 90.5% using ruthenium and 111% using sodium hydroxide. The process waters from the hydrothermal liquefaction (HTL) of microalgae (Chlorella, Pseudochoricystis, and Spirulina) were gasified under supercritical water conditions to maximise hydrogen production. Hydrogen yields ranged from 0.18-0.29 g H2 / g biocrude from SCWG of the process water of HTL along with near complete gasification of the organics (~98%). Compared to the hydrogen requirements for hydrotreating algal biocrude (~0.05 g H2 / g biocrude), excess hydrogen can be produced from upgrading the process water through SCWG. The results indicate that process waters following SCWG are still rich in nutrients that can be recycled for algal cultivation

The cognitive model in the education philosophy of Majid Arsan Al-Kilani

ترمي هذه الورقة البحثية  إلى الوقوف على أهم القواعد المنهجية والمعرفية للنموذج المعرفي التربوي عند ماجد عرسان الكيلاني (1927-2015م). والذي يبحث عملية التغيير والإصلاح والتجديد، وبناء نهضة الأمة الإسلامية. ولقد اشتغل الكيلاني في هذا البراديغم على دراسة الظواهر التربوية كظواهر اجتماعية باللجوء إلى أدوات منهجية اكتشف بعضها في مبادئه المعرفية.  والعمل على هذا النموذج المعرفي يطرح أكثر من رؤية. بالنظر إلى أهمية النموذج التربوي في تحديد معالم الإنسان المعاصر، وترسيخ الوعي السُنّني الكوني، وفهم أدواره المعرفية والقيميّة والثقافيّة والتاريخيّة والحضاريّة، لإعادة بناء منظومته المفاهيمية، وصياغة مناهجه العلمية، للانخراط في عملية إعداد النموذج التربوي للمجتمع الحضاري الذي يرمي إلى إعادة  هيكلته وبناءه، بتحديد الأسس النظرية والمعرفية والمنهجية لهذا النموذج، وشروط تأسيسه، وأبعاده المعرفية والحضارية.This research paper aims to identify the most important methodological and cognitive rules of The Educational Cognitive Model of Majid Arsan Al-Kilani, which examines the process of change, reform, renewal and building the renaissance of the Islamic nation. In this paradigm, Al-Kilani worked on the study of educational phenomena as social phenomena by resorting to methodological tools, some of which were discovered in his cognitive principles. And working on this cognitive model poses more of a vision. In view of the importance of the educational model in defining the features of modern man, the consolidation of cosmic age awareness, understanding of its cognitive, value, cultural, historical and civilizational roles, to rebuild its conceptual system and formulate its scientific approaches, to engage in the process of preparing the educational model of the civilizational community, which aims to restructure and build it

Hydrogen production from the catalytic supercritical water gasification of process water generated from hydrothermal liquefaction of microalgae

The integration of hydrothermal liquefaction (HTL) and hydrothermal gasification (HTG) is an option for enhanced energy recovery and potential biocrude upgrading. The yields and product distribution obtained from the HTL of Chlorella vulgaris have been investigated. High conversion of algae to biocrude as well as near complete gasification of the remaining organic components in the aqueous phase was achieved. The aqueous phase from HTL was upgraded through catalytic HTG under supercritical water conditions to maximise hydrogen production for biocrude hydrotreating. High yields of hydrogen were produced (∼30 mol H2/kg algae) with near complete gasification of the organics (∼98%). The amount of hydrogen produced was compared to the amounts needed for complete hydrotreating of the biocrude. A maximum of 0.29 g H2 was produced through HTG per gram of biocrude produced by HTL. The nutrient content of the aqueous phase was analysed to determine suitability of nutrient recovery for algal growth. The results indicate the successful integration of HTL and HTG to produce excess hydrogen and maintain nutrient recovery for algal growth

A parametric study on supercritical water gasification of Laminaria hyperborea: a carbohydrate-rich macroalga.

The potential of supercritical water gasification (SCWG) of macroalgae for hydrogen and methane production has been investigated in view of the growing interest in a future macroalgae biorefinery concept. The compositions of syngas from the catalytic SCWG of Laminaria hyperborea under varying parameters including catalyst loading, feed concentration, hold time and temperature have been investigated. Their effects on gas yields, gasification efficiency and energy recovery are presented. Results show that the carbon gasification efficiencies increased with reaction temperature, reaction hold time and catalyst loading but decreased with increasing feed concentrations. In addition, the selectivity towards hydrogen and/or methane production from the SCWG tests could be controlled by the combination of catalysts and varying reaction conditions. For instance, Ru/Al2O3 gave highest carbon conversion and highest methane yield of up to 11 mol/kg, whilst NaOH produced highest hydrogen yield of nearly 30 mol/kg under certain gasification conditions

Influence of reaction conditions on the composition of liquid products from two-stage catalytic hydrothermal processing of lignin.

The influence of reaction conditions on the composition of liquid products during two-stage hydrothermal conversion of alkali lignin has been investigated in a batch reactor. Reactions were carried out in the presence of formic acid (FA) and Pt/Al2O3 catalyst. The two different sets of reaction conditions involved alternative reaction times of 1 h and 5 h at 265 °C and 350 °C, respectively. These provided different contributions to reaction severity, which affected the compositions of liquid products. Yields of liquid products reached up to 40 wt% (on lignin feed basis) in the presence of FA under the less severe reaction condition. With 5 h reaction time at 350 °C, alkylphenols, alkylguaiacols and hydrocarbons were the dominant liquid products. However, with 5 h reaction time at 265 °C, phenol and methanol became dominant. The two-stage hydrothermal process led to improved lignin conversion, with the potential to manipulate the liquid product range

Recovery of carbon fibres and production of high quality fuel gas from the chemical recycling of carbon fibre reinforced plastic wastes

A solvolysis process to depolymerize the resin fraction of carbon fibre reinforced plastic waste to recover carbon fibre, followed by hydrothermal gasification of the liquid residual product to produce fuel gas was investigated using batch reactors. The depolymerisation reactions were carried out in ethylene glycol and ethylene glycol/water mixtures at near-critical conditions of the two solvents. With ethylene glycol alone the highest resin removal of 92.1% was achieved at 400 °C. The addition of water to ethylene glycol led to higher resin removals compared to ethylene glycol alone. With an ethylene glycol/water ratio of 5, at 400 °C, resin removal was 97.6%, whereas it was 95.2% when this ratio was 3, at the same temperature. The mechanical properties of the recovered carbon fibre were tested and showed minimal difference in strength compared to the virgin carbon fibre. The product liquid, containing organic resin degradation products was then subjected to catalytic supercritical water gasification at 500 °C and 24 MPa in the presence of NaOH and Ru/AlO as catalysts, respectively. Up to 60 mol.% of H gas was produced with NaOH as catalyst, and 53.7 mol.% CH gas was produced in the presence of Ru/AlO

A perspective on algae, the environment, and energy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100329/1/ep11847.pd

Production of bio-coal, bio-methane and fertilizer from seaweed via hydrothermal carbonisation

Macroalgae has emerged as a potential future source of feedstock for the production of chemicals and biofuels. The main drawback of macroalgae in terms of a biofuel feedstock is its low heating value (HHV), high halogen content, high ash content and high slagging and fouling propensity. In this investigation, three species of kelps; (i) Laminaria digitata (ii) Laminaria hyperborea and (iii) Alaria esculenta have been processed by hydrothermal carbonisation (HTC) in a batch reactor at two temperatures (200 °C and 250 °C). The yields and properties of the resulting hydrochars including their HHV, CHNS, mineral content and ash fusibility properties have been determined and compared to the starting material. Significant improvement in fuel quality is observed resulting in an increase in energy density from 10 MJ/kg to typically 25 MJ/kg, which is comparable to that of a low rank coal. The results indicate significant demineralisation of the fuel, in particular a significant removal of alkali salts and chlorine. This results in improved combustion properties due to a reduction in the slagging and fouling properties of the fuel. Analysis of the HTC water phase indicates the presence of high levels of soluble organic carbon consisting of sugars and organic acids, and high levels of potassium, magnesium and phosphorous. The potential for production of bio-methane and recovery of nutrients following anaerobic treatment of the water phase is assessed. A prediction of the bio-methane yields for the different seaweeds has been calculated. Processing of biomass collected throughout the growth season indicates the influence of seasonal variation on energy and nutrient recovery