وقود الديزل الحيوي

هي الوقت البديلة النظيفة المنجة محليا والتى تعد من الموارد المتجددة  وهذه الوقود عبارة عن خليط من  استرات ألكيل الدهنية حمض مصنوعة من الزيوت النباتية،و  الدهون الحيوانية أو الشحوم المعاد تدويرهاحيثما كان ذلك متاحا، وقود الديزل الحيوي يمكن استخدامها في ضغط الاشتعال (الديزل) محركات في شكله النقي مع تعديلات ضئيلة أو معدومة. وقود الديزل الحيوي هو سهلة الاستخدام، والقابلة للتحلل غير سام، وخالية أساسا من الكبريت والعطريات. عادة ما يتم استخدامه كمادة مضافة الديزل النفطية للحد من مستويات الجسيمات وأول أكسيد الكربون والهيدروكربونات والمواد السامة من السيارات العاملة على المازوت. عندما تستخدم كمادة مضافة، وقود الديزل الناتجة يمكن أن يسمى ب5، ب10 أو ب20،وهو ما يمثل نسبة وقود الديزل الحيوي الذي يتم مزجه مع الديزل النفطي.

ويتم إنتاج وقود الديزل الحيوي من خلال عملية تجمع بين الزيوت المشتقة عضويا مع الكحول (الإيثانول أو الميثانول) في وجود عامل حفاز لتشكيل إيثيل استر الميثيل أو. يمكن مزجه إيثيل الميثيل أو استرات الكتلة الحيوية المشتقة مع وقود الديزل التقليدية أو استخدامها كوقود أنيق (100٪ وقود الديزل الحيوي). وقود الديزل الحيوي يمكن أن تكون مصنوعة من أي زيت نباتي، والدهون الحيوانية والزيوت النباتية النفايات، أو زيوت الطحالب. هناك ثلاث طرق أساسية لإنتاج وقود الديزل الحيوي من الزيوت والدهون:

قاعدة المحفزة عبر الأسترة للنفط

حمض المباشر المحفزة عبر الأسترة للنفط

تحويل النفط إلى الأحماض الدهنية وبعد ذلك إلى وقود الديزل الحيوي.

 

وهناك مجموعة متنوعة من الزيوت التي تستخدم لانتاج وقود الديزل الحيوي، وأكثرها شيوعا هي فول الصويا وبذور اللفت، وزيت النخيل والتي تشكل الغالبية العظمى من إنتاج وقود الديزل الحيوي في جميع أنحاء العالم. المواد الأولية الأخرى يمكن أن تأتي من النفط النفايات النباتية، والجاتروفا، والخردل، والكتان وعباد الشمس، وزيت النخيل أو القنب. الدهون الحيوانية بما في ذلك الشحم، شحم الخنزير، والشحوم الصفراء والدهون والدجاج وزيت السمك من المنتجات يمكن أن تسهم نسبة صغيرة لإنتاج الديزل الحيوي في المستقبل، لكنها محدودة في العرض وغير فعالة لتربية الحيوانات من أجل الدهون. الجاتروفا هو صغير من الآفات ومقاومة للجفاف شجيرة التي هي قادرة على أن تزرع في الهامشية / الأراضي المتدهورة وتنتج البذور التي تدر عدة مرات المزيد من النفط للدونم الواحد من فول الصويا.

وهناك مجموعة متنوعة من الزيوت التي تستخدم لانتاج وقود الديزل الحيوي، وأكثرها شيوعا هي فول الصويا وبذور اللفت، وزيت النخيل والتي تشكل الغالبية العظمى من إنتاج وقود الديزل الحيوي في جميع أنحاء العالم. المواد الأولية الأخرى يمكن أن تأتي من النفط النفايات النباتية، والجاتروفا، والخردل، والكتان وعباد الشمس، وزيت النخيل أو القنب. الدهون الحيوانية بما في ذلك الشحمر، والشحوم الصفراء والدهون والدجاج وزيت السمك من المنتجات يمكن أن تسهم نسبة صغيرة لإنتاج الديزل الحيوي في المستقبل، لكنها محدودة في العرض وغير فعالة لتربية الحيوانات من أجل الدهون. الجاتروفا هو صغير من الآفات ومقاومة للجفاف شجيرة التي هي قادرة على أن تزرع في الهامشية / الأراضي المتدهورة وتنتج البذور التي تدر عدة مرات المزيد من النفط للدونم الواحد من فول الصويا.

بين المواد الأولية البديلة، يحمل الطحالب إمكانات هائلة لتوفير المواد غير الغذائية، وارتفاع العائد المرتفع وغير الصالحة للزراعة المصدر استخدام الأراضي وقود الديزل الحيوي والإيثانول والهيدروجين وقود. الطحالب قد تشد الانتباه لأن الوقود الحيوي على أساس فدان بواسطة فدان، الطحالب يمكن أن تنتج 100-300 مرة من العائد النفطي من فول الصويا على الأراضي الهامشية ومع المياه المالحة. الطحالب هو الكائن الحي photosynthesizing الأسرع نموا، وقادر على استكمال دورة النمو بأكمله كل بضعة أيام.

ترجمة 

سجى البغدادي  –طالبة  بكالوريس ادارة مياه وبيئة في  الجامعة الهاشمية ومنسقة كلية الموارد الطبيعة   ناشطة ومتتطوعة  مع عدة مبادرات و مهتم في مجال البيئة والمياه و  التغير المناخ

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Algae Biorefinery – Promise and Potential

High oil prices, competing demands between foods and other biofuel sources, and the world food crisis, have ignited interest in algaculture (farming of algae) for making vegetable oil, biodiesel, bioethanol, biogasoline, biomethanol, biobutanol and other biofuels. Algae can be efficienctly grown on land that is not suitable for agriculture and hold huge potential to provide a non-food, high-yield source of biodiesel, ethanol and hydrogen fuels. 

Several recent studies have pointed out that biofuel from microalgae has the potential to become a renewable, cost-effective alternative for fossil fuel with reduced impact on the environment and the world supply of staple foods, such as wheat, maize and sugar.

What are Algae?

Algae are unicellular microorganisms, capable of photosynthesis. They are one of the world’s oldest forms of life, and it is strongly believed that fossil oil was largely formed by ancient microalgae. Microalgae (or microscopic algae) are considered as a potential oleo-feedstock, as they produce lipids through photosynthesis, i.e. using only carbon , water, sunlight, phosphates, nitrates and other (oligo) elements that can be found in residual waters. Oils produced by diverse algae strains range in composition. For the most part are like vegetable oils, though some are chemically similar to the hydrocarbons in petroleum.

Advantages of Algae

Apart from lipids, algae also produce proteins, isoprenoids and polysaccharides. Some strains of algae ferment sugars to produce alcohols, under the right growing conditions. Their biomass can be processed to different sorts of chemicals and polymers (Polysaccharides, enzymes, pigments and minerals), biofuels (e.g. biodiesel, alkanes and alcohols), food and animal feed (PUFA, vitamins, etc.) as well as bioactive compounds (antibiotics, antioxidant and metabolites) through down-processing technology such as transesterification, pyrolysis and continuous catalysis using microspheres.

Algae can be grown on non-arable land (including deserts), most of them do not require fresh water, and their nutritional value is high. Extensive R&D underway on algae as raw material worldwide, especially in North America and Europe with a high number of start-up companies developing different options.

Most scientific literature suggests an oil production potential of around 25-50 ton per hectare per year for relevant algae species. Microalgae contain, amongst other biochemical, neutral lipids (tri-, di-, monoglycerides free fatty acids), polar lipids (glycolipids, phospholipids), wax esters, sterols and pigments. The total lipid content in microalgae varies from 1 to 90 % of dry weight, depending on species, strain and growth conditions.

Algae-based Biorefinery

In order to develop a more sustainable and economically feasible process, all biomass components (e.g. proteins, lipids, carbohydrates) should be used and therefore biorefining of microalgae is very important for the selective separation and use of the functional biomass components.

The term biorefinery was coined to describe the production of a wide range of chemicals and bio-fuels from biomasses by the integration of bio-processing and appropriate low environmental impact chemical technologies in a cost-effective and environmentally sustainable. If biorefining of microalgae is applied, lipids should be fractionated into lipids for biodiesel, lipids as a feedstock for the chemical industry and essential fatty acids, proteins and carbohydrates for food, feed and bulk chemicals, and the oxygen produced should be recovered also.

The potential for commercial algae production is expected to come from growth in translucent tubes or containers called photo bioreactors or in open systems (e.g. raceways) particularly for industrial mass cultivation or more recently through a hybrid approach combining closed-system precultivation with a subsequent open-system. Major advantages of a algal biorefinery include:

  • Use of industrial refusals as inputs ( CO2,wastewater and desalination plant rejects)
  • Large product basket with energy-derived (biodiesel, methane, ethanol and hydrogen) and non-energy derived (nutraceutical, fertilizers, animal feed and other bulk chemicals) products.
  • Not competing with food production (non-arable land and no freshwater requirements)
  • Better growth yield and lipid content than crops.

Indeed, after oil extraction the resulting algal biomass can be processed into ethanol, methane, livestock feed, used as organic fertilizer due to its high N:P ratio, or simply burned for energy cogeneration (electricity and heat). If, in addition, production of algae is done on residual nutrient feedstocks and CO2, and production of microalgae is done on large scale in order to lower production costs, production of bulk chemicals and fuels from microalgae will become economically, environmentally and ethically extremely attractive.

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Saudi Arabia Biorefinery from Algae (SABA) Project

The King Abdulaziz City for Science & Technology (KACST) is funding an innovative project called Saudi Arabia Biorefinery from Algae (SABA Project) to screen for lipid hyper-producers species in Saudi Arabia coastal waters. These species will be the basis for next-generation algal biofuel production. The goal of this project is to increase research and training in microalgae-based biofuel production as well algal biomass with an additional goal of using a biorefinery approach that could strongly enhance Saudi Arabia economy, society and environment within the next 10 years.

The primary mission of the SABA project is to develop the Algae Based Biorefinery – ABB biotechnology putting into operation innovative, sustainable, and commercially viable solutions for green chemistry, energy, bio-products, water conservation, and CO2 abatement. Microalgae are known sources of high-value biochemicals such as vitamins, carotenoids, pigments and anti-oxidants. Moreover, they can be feedstocks of bulk biochemicals like protein and carbohydrates that can be used in the manufacture of feed and food.

The strategic plan for SABA project is based on the achievement of the already ongoing applied Research, Technology Development & Demonstration (RTD&D) to the effective use of microalgae biomass production and downstream extraction in a diversified way, e.g. coupling the biomass production with wastewater bioremediation or extracting sequentially different metabolites form the produced biomass (numerous fatty acids, proteins, bioactive compounds etc.). This interdisciplinary approach including algal biology, genetic engineering and technologies for algae cultivation, harvesting, and intermediate and final products extraction is crucial for the successful conversion of the developed technologies into viable industries.

The first phase of this project entitled “Screening for lipid hyper-producers species in Saudi Arabia coastal waters for Biofuel production from micro-Algae” will build the basis for large scale system to produce diesel fuel and other products from algae grown in the ocean with a strong emphasis on building know-how and training. It will ultimately produce competitively priced biofuel, scaling up carbon capture for a range of major environmental, economic, social and climate benefits in the Kingdom and elsewhere. The project lends itself to an entrepreneurial new venture, working in partnership with existing firms in the oil and gas industry, in energy generation, in water supply and sanitation, in shipping and in food and pharmaceutical production.

The project is gaining from cross-disciplinary cutting edge Research, Technology Development & Demonstration for the industrial implementation of the fourth generation algae-based Biorefinery. The technology development is supported by a consortium of engineers, researchers in cooperation with industry players (to ensure technology transfer), international collaborators (to ensure knowledge transfer) and the Riyadh Techno Valley (to promote spin-off and commercialization of results). 

Since the research topic is innovative in the Kingdom research circles, a strong research partnership was promptly developed by the King Saud University / King Abdulah Institute for Nanotechnology with international distinguished research centers with proved successful experience in this technology development. The Centre of Marine Science (CCMAR) and the Institute of Biotechnology and Bioengineering (IBB) both from Portugal are a guarantee to the successful research-based technology development in the SABA project development and the effective capacity-building for Saudi young researchers and technicians.

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What are Biofuels

The term ‘Biofuel’ refers to liquid or gaseous fuels for the transport sector that are predominantly produced from biomass. A variety of fuels can be produced from biomass resources including liquid fuels, such as ethanol, methanol, biodiesel, Fischer-Tropsch diesel, and gaseous fuels, such as hydrogen and methane. The biomass resource base for biofuel production is composed of a wide variety of forestry and agricultural resources, industrial processing residues, municipal solid wastes and urban wood residues.

The agricultural resources include grains used for biofuels production, animal manures and residues, and crop residues derived primarily from corn and small grains (e.g., wheat straw). A variety of regionally significant crops, such as cotton, sugarcane, rice, and fruit and nut orchards can also be a source of crop residues. The forest resources include residues produced during the harvesting of forest products, fuelwood extracted from forestlands, residues generated at primary forest product processing mills, and forest resources that could become available through initiatives to reduce fire hazards and improve forest health. Municipal and urban wood residues are widely available and include a variety of materials — yard and tree trimmings, land-clearing wood residues, wooden pallets, organic wastes, packaging materials, and construction and demolition debris.

Globally, biofuels are commonly used to power vehicles, heat homes, and for cooking. Biofuel industries are expanding in Europe, Asia and the Americas. Biofuels are generally considered as offering many priorities, including sustainability, reduction of greenhouse gas emissions, regional development, social structure and agriculture, and security of supply. 

First Generation Biofuels

First-generation biofuels are made from sugar, starch, vegetable oil, or animal fats using conventional technology. The basic feedstocks for the production of first-generation biofuels come from agriculture and food processing. The most common first-generation biofuels are:

  • Biodiesel: extraction with or without esterification of vegetable oils from seeds of plants like soybean, oil palm, oilseed rape and sunflower or residues including animal fats derived from rendering applied as fuel in diesel engines
  • Bioethanol: fermentation of simple sugars from sugar crops like sugarcane or from starch crops like maize and wheat applied as fuel in petrol engines
  • Bio-oil: thermo-chemical conversion of biomass. A process still in the development phase
  • Biogas: anaerobic fermentation or organic waste, animal manures, crop residues an energy crops applied as fuel in engines suitable for compressed natural gas.

 

First-generation biofuels can be used in low-percentage blends with conventional fuels in most vehicles and can be distributed through existing infrastructure. Some diesel vehicles can run on 100 % biodiesel, and ‘flex-fuel’ vehicles are already available in many countries around the world.

Second Generation Biofuels

Second-generation biofuels are derived from non-food feedstock including lignocellulosic biomass like crop residues or wood. Two transformative technologies are under development.

  • Biochemical: modification of the bio-ethanol fermentation process including a pre-treatment procedure
  • Thermochemical: modification of the bio-oil process to produce syngas and methanol, Fisher-Tropsch diesel or dimethyl ether (DME).

Advanced conversion technologies are needed for a second generation of biofuels. The second generation technologies use a wider range of biomass resources – agriculture, forestry and waste materials. One of the most promising second-generation biofuel technologies – ligno-cellulosic processing (e. g. from forest materials) – is already well advanced. Demonstration plants have already been established in Denmark, Spain and Sweden.

Third Generation Biofuels

Third-generation biofuels may include production of bio-based hydrogen for use in fuel cell vehicles from microalgae. The production of Algae fuel, also called Oilgae is supposed to be low cost and high-yielding – giving up to nearly 30 times the energy per unit area as can be realized from current, conventional ‘first-generation’ biofuel feedstocks. Algaculture can be an attractive route to making vegetable oil, biodiesel, bioethanol and other biofuels.

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الطحالب – معمل وقود حيوي

اتجهت أبحاث الخبراء والمتخصصين فى الفترة الأخيرة إلى التركيز علي إنتاج الوقود الحيوى من الطحالب الخضراء، خاصة بعد إقرار بدء مرحلة نضوب النفط فى فترة زمنية قريبة، وأنه سينضب أكثر من 95% من مصادر البترول الموجودة على سطح الأرض وايضا مشكله الغذاء المحتمل حدوثها في حاله استخدام المنتجات الزراعيه او مخلفاتها في الوقود الحيوي لانتاج منتجات الوقود مثل وقود الديزل الحيوي, الايثانول, الجازولين الحيوي و غيرهم من منتجات الوقود الحيوي.

وقد اشارت االعديد من الدراسات الحديثه الي ان الطحالب الخضراء كمصدر للوقود تندرج تحت لواء مصادر الطاقه المتجددة وخاصا بعد التزايد المستمر في سعر الوقود الاحفوري. فهي تنمو بسرعة ولها أثر محدود على البيئة ولا تؤثر علي الاحتياج العالمي للغذاء مثل القمح والذرة والسكر.

ما هي الطحالب؟

الطحالب هي كائنات دقيقة وحيدة الخلية ولها قدرة علي التمثيل الضوئي. تتميز بمعدل نمو سريع. تعتبرمن اقدم انواع الحياه علي وجه الارض. حيث يعتقد ان الوقود الاحفوري تكون من الطحالب في العصر القديم. وتتتم عملية البناء الضوئي في ظل استخدام الكربون والمياه في وجود اشعه الشمس و نسب بسيطة من الفوسفات والنترات والتي ممكن الحصول عليها من مياه الصرف. وفي ظل وجود الظروف الجيدة للنمو , تضاعف الطحالب نموها خلال 24ساعة. باضافة الى ذلك, الطحالب تحتوى على محتوى زيت يزداد عن 50% من محتواها الكتلي في بعض انواع الطحالب لذا تم استغلال هذه النسبة لانتاج الوقود. وتنتج سلالات متنوعه تترواح في تركيبها باشكال تتشابهه كميائيا لسلسله الهيدروكربونات البترولية.

مميزات الطحالب

بخلاف ان الطحالب تنتج الدهون, تقوم ايضا بانتاج البروتين ومركبات الكربون والسكريات. وبعض سلالات الطحالب تقوم بتكسير مركبات السكريات لانتاج الكحول في ظل توافر الظروف المناسبة للتفاعل.

والكتله الحيوية للطحالب يمكنها التشكل لانواع مختلفة من المواد الكميائية والبوليمرات, (السكريات، والإنزيمات، أصباغ ومعادن). او الوقود الحيوي (مثل وقود الديزل الحيوي, مواد قلويه, كحول). غذاء وعلف ( مثل الاحماض الدهنية غير المشبعه, فيتامينات وغيرها) و ايضا المركبات النشطة بيولوجيا (مثل المضادات الحيويه, مضادات الاكسدة والتمثيل الغذائي) من خلال تقنيات المعالجة والمحفزات المجهرية والتحلل الحراري.

كما أن الوقود الحيوي المشتق من الطحالب لا يشارك الإيثانول في بعض الصفات غير المرغوب فيها، حيث إنه يمكن تحويل الطحالب إلى شكل مصنع من أشكال وقود البنزين، الديزل أو وقود الطائرات، أو إلى مادة خام مثل النفط يمكن معالجتها في المصافي التقليدية. لكن إنتاج الوقود الحيوي من الطحالب يجابه في الوقت الحاضر تحديا كبيرا جدا يتمثل في ارتفاع تكاليف الإنتاج بصورة كبيرة.

من اهم ما يميز استخدام الطحالب كبديل للوقود انها لا تحتاج الي اراضي صالحة للزراعه فمن الممكن زراعتها في الصحاري, كما انها لا تتطلب مياه عذبة وقيمتها الغذائية عالية. هناك الكثير من الابحاث المركزة علي الطحالب الخضراء في جميع انحاء العالم, وبالاخص في امريكا الشمالية واروبا مع عدد كبير من الشركات التي خصصت مبالغ مالية كبير لتطوير الابحاث المنعقدة علي الطحالب الخضراء كمصدر بديل للوقود الاحفوري.

وفى إنتاج الوقود السائل من الطحالب يتم بطريقة كيميائية بسيطة؛ إذ يجرى تحويل الزيوت المستخلصة إلى ديزل حيوى، وإن هناك نوعين من الطحالب يستخدمان فى هذه العملية: الأعشاب البحرية التى يوجد بها كمية كبيرة من الزيت يتم درسها ثم استخلاص الزيوت منها لتحويلها إلى وقود، والثانى الطحالب الدقيقة التى تُزرع داخل المعمل؛ حيث تُعرف نسبة الزيت الموجودة داخل الخلية ثم يبدأ التغيير فى الوسط الغذائى لها، وكلما كانت نسبة الدهون أعلى كان أفضل.

 وتشير معظم الدراسات العلمية الي امكانية انتاج الزيوت من حوالي 25-50 طن للهكتار الواحد سنويا من الطحالب الخضراء. وتحتوي الطحالب الدقيقة, من بين بعض المركبات البيوكيميائية الاخري علي الدهون المحايدة( ثلاثي, ثنائي, احادي الجلسريد احماض دهنية حره), والدهون القطبية (الدهون السكرية, الدهون الفوسفاتية) و استرات الشمع.  

يختلف المحتوي الدهني للطحالب المجهريه 1-90% من الوزن الجاف ويوقف علي نوع وسلاله الطحالب وظروف الانتاج. أن عملية إنتاج الوقود من الطحالب تمر بعدة مراحل؛ ففى البداية لا بد من تأكد جودة الزيت الموجود داخل الخلايا ثم استخلاصه، وفى النهاية، وبمعادلة كيميائية، يتم تحويل الزيوت إلى بيوديزل.

واستخدام الطحالب كسماد اثبت كفاءة عالية للانتاج,فأى محصول زراعى يحتاج إلى عناصر غذائية معينة، كوحدات البوتاسيوم والأوكسجين ووحدات الفوسفور، ومن ثم فهى تحتاج إلى أى مركب يحتوى على هذه العناصر والطحالب غنية بها.

مرحلة الانتاج والتكرير

من اجل تطوير مستدام والحصول علي المردود الاقتصادي المطلوب من استخدام الطحالب, فان استخدام الكتله الحيوية( بروتين, دهون وكربوهيدات) لابد ان يتم الانتفاع بها. ومن هنا يتضح اهمية التكرير للطحالب المجهرية ليتم فصل و تحديد الكتله الحيوية المطلوب الحصول عليها. ان مصطلح التكرير يوصف تحليل وتجزئة العديد من السلاسل الكميائية بواسطة التكامل بين العمليات الحيوية في ضوء الاستدامة وخفض التكلفة مع التركيز علي الكفاءة البيئة.

عند تطبيق التكرير البيولوجي للطحالب, فان الدهون تنقسم الي نوعين: دهون صالحة للوقود الحيوي ودهون صالحة كمادة اوليه للمنتجات الكميائية في الصناعة و الاحماض الدهنية الضرورية لذلك. البروتين والكربوهيدرات الناتجة تكون صالحة للغذاء والاعلاف وبعض المنتجات الكميائية. اما بالنسبة للاكسجين الناتج فيتم تجميعه وحفظه في الحاويات المخصصه لذلك.  

الانتاج التجاري للطحالب الخضراء قائم علي استخدم تقنيات مختلفة للانتاج: استخدام الانابيب الشفافة او حاويات تسمي المفاعلات الحيوية او النظام المفتوح (مثل استخدام المجاري المائية) والاخيره تختص للانتاج الصناعي الكبير. وفي الاونة الاخيرة اصبح متبع النظام الجامع ما بين النظمين المغلق في المرحلة الاولي ثم النظام المفتوح لاحقا به.

وتعد مزارع انتاج الطحالب ذات منافع متعددة وتشمل:

استخدام المخلفات الصناعية كمدخلات انتاج ( مخلفات الحرق مثل ثاني اكسيد الكربون, مخلفات المياه الصناعية وايضا مخلفات محطات التحلية).

تنوع المخرجات الناتجة. ف.هناك مخرجات لانتاج طاقة حرارية ( ديزل حيوي, ميثان, ايثانول و هيدروجين). منتجات غير حرارية ( غذاء, اسمدة, اعلاف حيوانية وغيرها من المواد الكميائية).

ليس لها اي تاثير علي انتاج الغذاء ( فهي لا تستخدم اراضي زراعية ولا مياه نفية).

انتاج مواد دهنية تفوق الانتاج من المحاصيل الزراعية.

بعد مرحلة استخلاص الزيوت من الطحالب ، يمكن الاستفادة منها كاعلاف غنية بالبروتين وصالحة للاستخدام فى تغذية الحيوان والدواجن والأسماك. كما انها تدخل في صناعه الايثانول والميثان والسماد العضوي, وذلك نظرا لارتفاع نسبة الامينات الموجبة الي الفوسفات السالبة N:P ratio)), و حرق المتبقيات الناتجة تستخدم لتوليد الطاقه ( حرارية و كهربية).

ويتم انتاج الطحالب الخضراء حاليا كبديل للوقود علي نطاق واسع من اجل خفض تكاليف الانتاج. ايضا انتاج الغذاء الكميائي والوقود من الطحالب سوف يخضع للكثير من التحسينات والتطورات اللازمة حتي تصبح ذات مردود اقتصادي وبيئي مناسب.

 

ترجمه:

هبة احمد مسلم- دكتور الهندسة البيئية. باحث في الشئون البيئية. معهد الدراسات والبحوث البيئيةجامعه عين شمس.

مدرس بالاكاديمية العربية للعلوم والتكنولوجيا والنقل البحري-  مصر.

التحكم في البيئة والطاقه داخل المباني.

هندسة الميكانيكة- وكيل محرك دويتس الالماني بمصر. 

للتواصل عبر hebamosalam2000@gmail.com

 

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A Primer on Biodiesel

Biodiesel is a clean burning alternative fuel produced from domestic, renewable resources. The fuel is a mixture of fatty acid alkyl esters made from vegetable oils, animal fats or recycled greases. Where available, biodiesel can be used in compression-ignition (diesel) engines in its pure form with little or no modifications.

Biodiesel is simple to use, biodegradable, nontoxic, and essentially free of sulphur and aromatics. It is usually used as a petroleum diesel additive to reduce levels of particulates, carbon monoxide, hydrocarbons and toxics from diesel-powered vehicles. When used as an additive, the resulting diesel fuel may be called B5, B10 or B20, representing the percentage of the biodiesel that is blended with petroleum diesel.

Biodiesel is produced through a process in which organically derived oils are combined with alcohol (ethanol or methanol) in the presence of a catalyst to form ethyl or methyl ester. The biomass-derived ethyl or methyl esters can be blended with conventional diesel fuel or used as a neat fuel (100% biodiesel). Biodiesel can be made from any vegetable oil, animal fats, waste vegetable oils, or microalgae oils. There are three basic routes to biodiesel production from oils and fats:

  • Base catalyzed trans-esterification of the oil
  • Direct acid catalyzed trans-esterification of the oil
  • Conversion of the oil to its fatty acids and then to biodiesel.

There are a variety of oils that are used to produce biodiesel, the most common ones being soybean, rapeseed, and palm oil which make up the majority of worldwide biodiesel production. Other feedstock can come from waste vegetable oil, jatropha, mustard, flax, sunflower, palm oil or hemp. Animal fats including tallow, lard, yellow grease, chicken fat and fish oil by-products may contribute a small percentage to biodiesel production in the future, but it is limited in supply and inefficient to raise animals for their fat. Jatropha is a small pest- and drought -resistant shrub that is capable of being grown on marginal/degraded land and produces seeds that yield several times more oil per acre than soybeans.

Biodiesel can be blended in any proportion with mineral diesel to create a biodiesel blend or can be used in its pure form. Just like petroleum diesel, biodiesel operates in the compression ignition (diesel) engine, and essentially requires very little or no engine modifications because the biodiesel has properties similar to mineral diesel. It can be stored just like mineral diesel and hence does not require separate infrastructure. The use of biodiesel in conventional diesel engines results in substantial reduction in the emission of unburned hydrocarbons, carbon monoxide, and particulates. There are currently a large number of existing biodiesel production plants globally, and a large number under construction or planned to supply the growing global demand.

Among alternative feedstocks, algae holds enormous potential to provide a non-food, high-yield, non-arable land use source of biodiesel, ethanol and hydrogen fuels. Microalgae have been grabbing biofuel attention because on an acre-by-acre basis, microalgae can produce 100 to 300 times the oil yield of soybeans on marginal land and with salt water. Microalgae is the fastest growing photosynthesizing organism and is capable of completing an entire growing cycle every few days.

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Jatropha’s Relevance for MENA

Jatropha is a genus of nearly 175 species of shrubs, low-growing plants, and trees.  However, discussions of Jatropha as a biodiesel are actually means a particular species of the plant, Jatropha curcas. The plant is indigenous to parts of Central America, however it has spread to other tropical and subtropical regions in Africa and Asia.

Jatropha curcas is a perennial shrub that, on average, grows approximately three to five meters in height. It has smooth grey bark with large and pale green leaves. The plant produces flowers and fruits are produced in winter or throughout the year depending on temperature and soil moisture. The curcas fruit contains 37.5 percent shell and 62.5 percent seed.  Jatropha curcas can be grown from either seed or cutting.

By virtue of being a member of the Euphorbiaceae family, Jatropha has a high adaptability for thriving under a wide range of physiographic and climatic conditions. It is found to grow in all most all parts of the country up to an elevation 3000 feet. Jatropha is suitable for all soils including degraded and barren lands, and is a perennial occupying limited space and highly suitable for intercropping.

Extensive research has shown that Jatropha requires low water and fertilizer for cultivation, is not grazed by cattle or sheep, is pest resistant, is easily propagated, has a low gestation period, and has a high seed yield and oil content, and produces high protein manure. Sewage effluents provide a good source of water and nutrients for cultivating Jatropha, though there are some risk of salinization in arid regions.

Pongamia pinnata or Karanj is another promising non-edible oil seed plant that can be utilized for oil extraction for biofuels. The plant is a native of India and grows in dry places far in the interior and up to an elevation of 1000 meters. Pongamia plantation is not much known as like Jatropha, but the cost effectiveness of this plant makes it more preferred than other feedstock. Pongamia requires about four to five times lesser inputs and giver two to three times more yield than Jatropha which makes it quite suitable for small farmers. However, Pongamia seeds have about 5-10 percent less oil content than Jatropha and the plant requires longer period to grow as the gestation period is about 6-8 years for Pongamia against 3-5 years in Jatropha

To conclude, Jatropha can be successfully grown in arid regions of the Middle East and North Africa (MENA) for biodiesel production. These energy crops are highly useful in preventing soil erosion and shifting of sand-dunes. The production of sewage-irrigated energy crops has good potential to secure additional water treatment and thus reduce adverse environmental impacts of sewage disposal. Countries in the Middle East, like Eqypt, Libya, Sudan, Jordan and Saudi Arabia, are well-suited to the growth of Jatropha plantations. Infact, Jatropha is already grown at limited scale in some Middle East countries, especially Egypt,  and tremendous potential exists for its commercial exploitation.

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Prospects of Algae Biofuels in GCC

Algae biofuels have the potential to become a renewable, cost-effective alternative for fossil fuels with reduced impact on the environment. Algae hold tremendous potential to provide a non-food, high-yield, non-arable land use source of renewable fuels like biodiesel, bioethanol, hydrogen etc. Microalgae are considered as a potential oleo-feedstock, as they produce lipids through photosynthesis, i.e. using only CO2, water, sunlight, phosphates, nitrates and other (oligo) elements that can be found in residual waters.

Algae also produce proteins, isoprenoids and polysaccharides. Some strains of algae ferment sugars to produce alcohols, under the right growing conditions. Their biomass can be processed to different sorts of chemicals and polymers (Polysaccharides, enzymes, pigments and minerals), biofuels (e.g. biodiesel, alkanes and alcohols), food and animal feed (PUFA, vitamins, etc.) as well as bioactive compounds (antibiotics, antioxidant and metabolites) through down-processing technology such as transesterification, pyrolysis and continuous catalysis using microspheres.

Microalgae are the fastest growing photosynthesizing organism capable of completing an entire growing cycle every few days. Up to 50% of algae’s weight is comprised of oil, compared with, for example, oil palm which yields just about 20% of its weight in oil. Algae can be grown on non-arable land (including deserts), most of them do not require fresh water, and their nutritional value is high. Extensive R&D efforts are worldwide, especially in North America and Europe, with a high number of start-up companies developing different options for commercializing algae farming.

Prospects of Algae Biofuels in GCC

The demand for fossil fuels is growing continuously all around the world and the GCC countries are not an exception. GCC’s domestic consumption of energy is increasing at an astonishing rate, e.g. Saudi Arabia’s consumption of oil and gas rose by about 5.9 percent over the past five years while electricity demand is witnessing annual growth rate of 8 percent. Although GCC countries are world’s leading producers of fossil fuels, several cleantech initiatives have been launched in last few years which shows the commitment of GCC countries in exploiting renewable sources of energy.

Algae biofuels present a good opportunity for GCC countries to offset the environmental impact of the oil and gas industry. The region is geographically ideal for mass production of algae because of the following reasons:

  • Presence of large tracts of non-arable lands (deserts) and extensive coastline.
  • Presence of numerous oil refineries and power plants (as points of CO2 capture) and desalination plants (for salt reuse).
  • Extremely favorable climatic conditions (highest annual solar irradiance).
  • Presence of a large number of sewage and wastewater treatment plants.
  • Existence of highly lipid productive microalgae species in coastal waters.

These factors makes it imperative on GCC countries to develop a robust Research, Development and Market Deployment plan for a comprehensive microalgal biomass-based biorefinery approach for bio-product synthesis. An integrated and gradual appreciation of technical, economic, social and environmental issues should be considered for a successful implementation of the microalgae-based oleo-feedstock (MBOFs) industry in the region.

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Introduction to Biorefinery

A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, and value-added chemicals from biomass. Biorefinery is analogous to today’s petroleum refinery, which produces multiple fuels and products from petroleum. By producing several products, a biorefinery takes advantage of the various components in biomass and their intermediates, therefore maximizing the value derived from the biomass feedstock.

A biorefinery could, for example, produce one or several low-volume, but high-value, chemical products and a low-value, but high-volume liquid transportation fuel such as biodiesel or bioethanol. At the same time, it can generate electricity and process heat, through CHP technology, for its own use and perhaps enough for sale of electricity to the local utility. The high value products increase profitability, the high-volume fuel helps meet energy needs, and the power production helps to lower energy costs and reduce GHG emissions from traditional power plant facilities.

Working of a Biorefinery

There are several platforms which can be used in a biorefinery with the major ones being the sugar platform and the thermochemical platform (also known as syngas platform).

Sugar platform biorefineries breaks down biomass into different types of component sugars for fermentation or other biological processing into various fuels and chemicals. On the other hand, thermochemical biorefineries transform biomass into synthesis gas (hydrogen and carbon monoxide) or pyrolysis oil.

The thermochemical biomass conversion process is complex, and uses components, configurations, and operating conditions that are more typical of petroleum refining. Biomass is converted into syngas, and syngas is converted into an ethanol-rich mixture. However, syngas created from biomass contains contaminants such as tar and sulphur that interfere with the conversion of the syngas into products. These contaminants can be removed by tar-reforming catalysts and catalytic reforming processes. This not only cleans the syngas, it also creates more of it, improving process economics and ultimately cutting the cost of the resulting ethanol.

Biorefineries would help utilize the optimum potential of wastes and help solve the problems of waste management and greenhouse gas emissions. Each of these three components could be converted, through enzymatic/chemical treatments into either hydrogen or liquid fuels. The pre-treatment processes involved with these, generate products like paper-pulp, HFCS, solvents, acetate, resins, laminates, adhesives, flavour chemicals, activated carbon, fuel enhancers, undigested sugars etc. which generally remain untapped in the traditional processes.

Prospects in MENA

The MENA region has significant biomass energy potential in the form of municipal wastes, crop residues, industrial wastes etc. Around the region, pollution of air, water and soil from different waste streams continues to grow. The major biomass producing countries in MENA are Egypt, Saudi Arabia, Yemen, Iraq, Syria and Jordan. Traditionally, biomass energy has been widely used in rural areas for domestic purposes in the MENA region, especially in Egypt, Yemen and Jordan. The escalating prices of oil and natural gas, the resulting concern over energy-security, have led the MENA nations to explore alternative sources of energy.  Biorefinery offers a plausible solution for augmenting energy supply, obtaining clean energy and production of a wide range of chemicals from a host of waste material, apart from associated waste management benefits.

Biofuels in Jordan: Perspectives

Jordan has good biofuels production potential in the form of crop residues, agro-industrial wastes and urban wastes. Biomass energy sector in Jordan is slowly, but steadily, developing. As per a recent World Bank report, the country is currently generating 3.5MW of power from biomass resources which represent 0.1% of the total energy demand in the country. However there is no available data on the amount of biofuels produced in Jordan. Jordan produces significant amount of biofuel feedstock in the form of lignocellulosic biomass, used cooking oil, animal tallow, agro-industrial wastes, industrial effluents etc. 

In Jordan, transportation sector alone is responsible of 51% of final energy consumption (MEMR, 2013) which makes it imperative on policy-makers to find alternative and renewable transportation fuels in the form of biodiesel, bioethanol, biogas, algae fuels etc. However, allocation, development and implementation of alternative fuels go hand in hand with the preparation of adequate policies and targets by the local government. Some of the major driving forces for development of biofuel sector in Jordan include reduced climate change impacts and decreased reliance on imported fossil fuels.

Biofuels and Jordan's Renewable Energy Law

The Jordanian Renewable Energy and Energy Efficiency (REEE) law no. 13 of the year 2012 announced bioenergy as a renewable source of energy and only focused on using biomass feedstock in the production of electricity without mentioning production of biofuels from these sources. In addition the directive on Regulating the Activity of Industrial Fuel from Waste announced two definitions namely biofuel and industrial fuel. Biofuel is defined as a hydrocarbon material produced from all kinds of vegetable oil and/or animal fats and/or used vegetable oils or any other resources, whereas industrial fuel is defined as a liquid or gaseous hydrocarbon materials produced from industrial waste, domestic waste, plastic materials, medical waste, used tires and other high carbonaceous materials. These wastes are considered to be a non-renewable source and the produced oil or gas a non-renewable fuel, regardless of the technology used in its production.

Thus, the current Jordanian energy policy underline biofuels produced from waste resources as a non-renewable source of energy which in the result deprives biofuel sector from being able to benefit from the renewable energy law and tax redemption bylaw No. 13 for the year 2015. In addition bylaw No.13 for the year 2015 only mention exemptions on biomass energy systems which produce electricity, specifically biomethane to electricity and direct combustion of waste to electricity which completely contradicts the definition of the industrial fuel as biomethane can be produced from solid waste using anaerobic digestion process. In addition despite defining biodiesel as a renewable energy source its production systems and production inputs were not added under the exemption by law No. 13 for the year of 2015.

To conclude, policy-makers and urban planners are strongly urged to take these important points into consideration to harness the untapped biofuel potential thus catalyzing the development of biomass energy sector in Jordan. In addition, Jordan can explore the development of commercial energy crop plantations like Jatropha, Pongamia, sweet sorghum, algae farms etc on marginalized lands to spur the growth of biofuels sector.

References

  1. http://www.memr.gov.jo/
  2. The Little Green Data Book (2014), World Bank.
  3. The Regional Solid Waste Exchange of Information and Experience Network in Mashreq and Maghreb Countries – Sweep Net (2013). Country Report on Solid Waste Management in Jordan.
  4. Ahmad Al-Rousan, Anas Zyadin, Salah Azzam, Mohammed Hiary (2013) “Prospects of Synthetic Biodiesel Production from Various Bio-Wastes in Jordan” Journal of Sustainable Bioenergy Systems, 3, pp 217-223