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Abstract

Content

Introduction

Biofuel is an alternative type of fuel which is obtained as a result of processing of products of vital activity of organisms, or organic industrial waste.

Biofuels are divided into primary and secondary. Primary biofuel is an organic material that is used in its natural form (wood, pellets, briquettes). Secondary biofuels can be divided into three generations (based on different parameters, such as processing technology, feedstock, etc.); produced by processing plant biomass and used in vehicles in various industrial processes [1].

1. Theme urgency

The search for new alternative sources of fuel is a topical issue for the whole world.

Currently, there are fuel, energy and environmental problems, such as coal, oil and natural gas. The increase in prices for oil and oil products, as well as the depletion of natural sources of fuel have led to the active development of scientific research in the direction of search and development of alternative technologies [2]. To date, there is no doubt that biofuels derived from renewable raw materials, agricultural waste and industrial waste can be a solution to energy problems. Already now in many leading countries of the world (the USA, Brazil, Germany, Japan, China, France, etc.) industrial production of environmentally friendly biofuels is mastered, raw materials for receiving which are vegetable and microbial biomass, waste of various productions [3].

Recently, special attention has been paid to the energy use of biomass, since under the condition of its continuous recovery there is no increase in the СО2 concentration in the atmosphere. In addition, there are huge surpluses of cultivated land in many countries of the world, some of which have already been successfully used for the cultivation of energy crops. In the near future, all surplus cultivated land is planned to be occupied by energy plantations. In Germany, for example, biomass cultivation on different types of energy plantations is expected to take place by 2030 on an area of 2,0–4,3 million hectares and by  2050 – on  the area of 4,2–6,1 million hectares out of 17,3 million hectares currently used in agricultural production [1].

2. Goal and tasks of the research

The aim of the study is to find ways to obtain different types of biofuels based on plant raw materials and organic waste.

Main tasks of the research:

  1. develop a experimental plant for biofuel production based on plant raw materials and organic waste;
  2. selection of feedstock for the biofuel production process;
  3. development of a mathematical model of biofuel production based on plant raw materials and organic waste.

Research object: plant raw materials and waste of organic origin.

Research subject: possibility of biofuel production on the basis of plant raw materials and organic waste.

Planned result:

  1. creating an installation;
  2. study of the dynamics of culture growth of microalgae;
  3. the possibility of obtaining a sufficient amount of lipid phase for further production of biodiesel.

3. Literature review

3.1 Solid biofuel

The most ancient type of fuel in mankind is wood, which is used today mainly as a by-product of forest management. Waste from harvesting and processing of wood in the form of scraps, sawdust, chips, bark constitute a significant mass of fuel. Volumes of such fuel make more than 50 % of volumes of preparations of wood.

Today, biomass resources are used by no more than 5 % [4]. Currently, in Russia about 140 million m3 of wood is harvested from the main use felling, not counting the felling of forest care. At the same time, more than half of the volume of logging and wood processing is accounted for waste. In the next five to seven years, the volume of logging can increase to 200 million m3. At carrying out cabins of care of the wood to 60 % of wood is low-quality, not having commodity value. The total volume of waste and low-grade wood is not less than 40–45 million m3 per year or at least 10–12 million tons of conventional fuel per year [5]. Wood biomass in the forest, as well as biowaste of processing plants, create the risk of fires, reproduction of forest pests, and are a source of greenhouse gases in the decay of biomass [6].

3.2 Liquid biofuel

The substance obtained during the processing of plant raw materials (corn, rape, sugar beet, sugar cane, etc.), wood waste by means of technologies based on the use of natural biological processes (for example, fermentation) is called liquid biofuel [7]. The main application of liquid biofuels are engines.

This type of biofuels, primarily bioethanol С2Н5ОН – ethyl alcohol. The most common raw materials for ethanol production are sugar production wastes: bagasse or molasses (sugar beet), as well as starch of corn, sorghum, potatoes, wheat and rice [4].

Fuel bioethanol is produced by fermentation of sugars with the use of technology in the production of food ethanol, but without additional purification stages. World production of bioethanol is about 40 billion liters, of which 45 % is in Brazil and 44,7 % – in the United States [1]. To date, bioethanol is not a complete substitute for gasoline. The main fuel used is mixed fuel containing 10 % ethanol and 90 % gasoline (E10 standard) [6].

Biodiesel is a biofuel based on vegetable or animal fats (oils), as well as products of their esterification. The raw materials for the production of biodiesel are fatty, less often are essential oils of various plants or algae: in Europe – rapeseed; USA – soy; in Indonesia, the Philippines – palm and coconut oil; in India – jatropha; Brazil – castor oil; Africa – soy. Also used waste vegetable oil, animal fats, fish oil [2].

Biodiesel has the same characteristics as conventional diesel oils. It serves as a fuel source in diesel internal combustion engines. Fast pyrolysis makes it possible to convert biomass into liquid, which is easier and cheaper to transport, store and use.

The most promising source of raw materials for the production of biodiesel are microalgae [8]. Main advantages: biodiesel is characterized by good lubricating properties, which prolongs the life of the engine; when the engine is running on biodiesel simultaneously lubricates its moving parts, which results in an increase in the service life of the engine and the fuel pump on average by 60 % [9]; there is no need to upgrade the engine; in comparison with conventional diesel fuel contains almost no sulfur; biodiesel production contributes to the introduction into circulation of low-quality unused agricultural land. The main drawback: in the cold season, it is necessary to heat the fuel coming from the fuel tank to the fuel pump, or use a mixture of 20 % biodiesel and 80 % mineral diesel fuel; store equipment filled with biodiesel for more than 3 months, it is not recommended, so it is prone to oxidation and sensitive to water condensing on the walls of the fuel tanks [4].

3.3 Gaseous biofuels

Biogas is a product of fermentation of organic waste (biomass), which is a mixture of methane and carbon dioxide [1]. The product of methane fermentation of organic substances of plant and animal origin, carried out by specific natural biocenosis of anaerobic bacteria. The content of methane in biogas varies depending on the chemical properties of the raw material and can range from 50 to 90 %. Depending on the nature of the feedstock, the biogas yield varies from 200 to 600 liters per 1 ton of absolutely dry matter [6].

Biohydrogen is hydrogen produced from biomass by thermochemical, electrochemical, biochemical or other means. In the thermochemical method, the biomass is heated without oxygen to a temperature of 500–800 оC (for wood waste), which is much lower than the temperature of the coal gasification process [4]. The process releases H2, CO and CH4. Biohydrogen can be obtained thermomechanical method of wood waste, but the cost of this method is too high. In the biochemical process, hydrogen is produced by various bacteria.

3.4 Microalgae for biodiesel

The most promising source of plant material for biofuel production are microalgae, which contain lipids (including triacylglycerols (TAG), necessary for the synthesis of biodiesel). The use of microalgae will reduce the consumption of water resources, as waste water can be used for their cultivation. Due to the rapid growth and reproduction of microalgae, it is possible to obtain fuels from 15 to 200 times more than from the best agricultural oilseeds [8].

Currently, biodiesel is produced from vegetable and animal oils. In the United States, biodiesel is produced mainly from soybeans. Other sources of biodiesel are canola oil, animal fat, palm oil and corn oil.

It is estimated that 0,53 billion m3 of biodiesel will be needed annually to replace all motor fuel in the US. These types of raw materials can not provide such a volume of production. In any case, for the cultivation of biomass on the basis of their required unrealistically large areas of land [10].

Shows that microalgae are the only source of biodiesel that has the potential to completely replace fossil fuels in the United States. Unlike other crops, microalgae grow extremely fast and double the biomass in 24 hours. The oil content in the range of 20–50 % is typical for many species of algae.

Some of their species contain up to 80 % oil. Depending on the type of microalgae contain different types of lipids, hydrocarbons and complex oils [10].

There are different designs of cultivators, but in the general scheme contain: reactor – a tank in which the growth and reproduction of culture; lighting unit, culture power, harvest, control.

Figure 4 shows the general scheme of the microalgae cultivation system.

The general scheme of the system of cultivation of microalgae

1 – storage tank; 2 – pump; 3 – bioreactor; 4 – settling tank; 5 – mechanical stirrer; 6 – sludge tank.

Figure 4 – The general scheme of the system of cultivation of microalgae
(animation: 5 frames, 7 cycles of recurrence, 92 KB)

The bioreactor has built-in side pipes for inflow and outflow. The inflow of final effluents is continuously pumped into the bioreactor, which is controlled by the pump. The outflow is unlimited to maintain a constant volume in the bioreactor. The feed flows from the bottom up, here the drains flow through the outlet pipe into the sump. Treated wastewater overflow in the wastewater, and the kelp is gathered on the bottom and are recycled back to the bioreactor. Algae and wastewater in the bioreactor are mixed with a mechanical agitator to preserve the movement and suspension of algae cells.

Conclusion

Improvement of the processes of chemical processing of plant biomass is aimed at improving the efficiency of its main components, as well as the creation of new methods of complex processing of plant waste.

At this stage of the study, the main goal is to achieve efficiency and control of photobioreactor.Grading and selection of nutrient medium compositionplaysa huge role in this, as well as the technology of effective cultivation of a strain of microalgae. As a result it will be possible to obtain environmentally friendly and widespread occurrence biofuel in the use.

This abstract refers to a work that has not been completed yet. Final completion: June 2020. The full text of the work and materials on the topic can be obtained from the author or his head only after the specified date.

References

  1. Виноградова А.В. Биотехнология топлива: учеб. пособие / А.В. Виноградова, Г.А. Козлова, Л.В. Аникина. – Пермь: Изд-во Перм. гос. техн. ун-та, 2008. – 212 с.
  2. Сидорович В. Мировая энергетическая революция: как возобновляемые источники энергии изменят наш мир. М., 2015.
  3. Безруких П.П. Возобновляемая энергетика: сегодня – реальность, завтра – необходимость. М.: Лесная страна, 2007. – 120 с.
  4. Гельфанд Е.Д. Технология биотоплив: учебное пособие для магистрантов. – Архангельск, 2012. – 60 с.
  5. Биоэнергетика: мировой опыт и прогноз развития: науч. аналит. обзор / под ред. д.э.н. С.Г. Митина – М.: ФГНУ Росинформагротех, 2007. – 204 с.
  6. Егорова Т.А. Основы биотехнологии: учеб. пособие для высш. пед. учеб заведений / Т.А. Егорова, С.М. Клунова, Е.А. Живухина. – М.: Издательский центр Академия, 2003. – 208 с.
  7. Биотехнология: принципы и применение / И. Хиггинс, Д. Бест и Дж. Джонс – М.: Мир, 1988. – 480 с.
  8. Гайсина Л.А. Современные методы выделения и культивирования водорослей / Л.А. Гайсина, А.И. Фазлутдинова, P.P. Кабиров. – Уфа: БГПУ, 2008. – 152с.
  9. Росс М.Ю. Биодизельное топливо из водорослей / М.Ю. Росс, Д.С. Стребков; под ред. проф. Ю.М. Щекочихина. – М., 2008. – 252 с.
  10. Кофман В.Я. Энергоэффективные очистные сооружения [Электронный ресурс]. – Режим доступа: Микроводоросли для биодизельного топлива