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AALTO UNIVERSITY SCHOOL OF CHEMICAL TECHNOLOGY KE Introduction to biorefineries and biofuels. Assignment 4: Algae

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AALTO UNIVERSITY SCHOOL OF CHEMICAL TECHNOLOGY KE Introduction to biorefineries and biofuels Assignment 4: Algae Aino Siirala Assigment submitted 13th Table of contents 1 Types of algae...
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AALTO UNIVERSITY SCHOOL OF CHEMICAL TECHNOLOGY KE Introduction to biorefineries and biofuels Assignment 4: Algae Aino Siirala Assigment submitted 13th Table of contents 1 Types of algae Algae cultivation and production Open pond systems Closed systems Fermentation Other systems Benefits Problems and challenges The current status and the future of algal biofuels References 1 Types of algae To date, algae are cultivated for food, feed, chemicals, plastics and fertilizers, for instance [1]. Algae produce various oils, long carbon chains, carbonrings and alcohols. All of them can be utilized for biofuel production such as biodiesel and jet fuel. [2] There are tens of thousands of species of algae. It is beneficial for the algae industry as there is a wide range of algae with various properties to choose from. Macroalgae are seaweeds which are used widely in food production. Microalgae, which have gained more research in the biofuel field, include cyanobacteria, green, brown and red algae and many other species. [3] Algae can be classified into autotrophic, heterotrophic and mixotrophic algae. Autotrophic algae (most algae) use photosynthesis to grow. They need sunlight, CO2 and nutrients, such as nitrogen and phosphorus. Heterotrophic algae can grow in the dark by using sugar or starch and mixotrophic algae combine both methods. [4] 2 Algae cultivation and production Algae can be cultivated in many ways. It can use sea-, brackish- or wastewater as a habitat. Macroalgae are normally cultivated in nearshore systems. [4] 2.1 Open pond systems The most common way to cultivate algae is in open pond systems. In the US, they are already used commercially to produce nutritional products and treat wastewater. The shallow ponds are positioned in sunlight to grow autotrophic algae. The system uses water moving devices to keep the algae circulating, [5] 2 A typical way is to harvest a fraction of the pond water every day. The algal biomass in the water is concentrated and processed further. The remaining biomass can be dried and used for animal feeds. [5] 2.2 Closed systems Autotrophic algae can be cultivated also in enclosed photobioreactors. There are various sizes and shapes of these transparent vessels. Some systems use additional artificial light. It is possible to feed the algae with enriched CO2 such as flue gases from power plants or gases from other fossil fuel combustion. The main advantange in a closed system is that unwanted weed algae do not grow easily in the system. [6] 2.3 Fermentation Fermentation is used for cultivating heterotrophic algae which grow in the dark. The algae need sugar or starch to produce oils which can be converted into biofuels. [7] Solarzyme, a San Francisco pioneer company in algae fermentation, has already produced large amounts of biofuel from algae for marine diesel and aviation fuel. [7] 2.4 Other systems Hybrid systems combine open pond systems, closed systems and fermentation [8]. Integrated systems exploit the algae s ability to treat wastewater or polluted air. These algae production systems can be fed with nutrient rich wastewater such as sewage, animal wastes or industrial effluents. [9] Excretion processes could be used for algae, which have been modified to give the useful chemical into the culture. [10] 3 3 Benefits The oils algae produce and store are not the only useful substance for biodiesel industry. It is possible to convert bioethanol from carbohydrates or make biodiesel from hydrocarbons via gasification and fischer-tropsch synthesis. Algal biomass can be combusted for power generation. [11] Algae grow very fast. They can double in less than 24 hours [12] and thus they are more productive than any crop used for energy production. Also, the space algae need is many times smaller compared to the biofuel productivity per hectare of energy crops. CO2 emission sources such as power plants can be used as a CO2 feedstock for algae production. Also, algae can purify wastewaters. [1] Algae do not compete with agriculture as it can be cultivated on wastelands [1]. The dried algal biomass, which is left after exracting the wanted substances, can be pelletized and used as fuel [1]. 4 Problems and challenges Algal biofuel is not at a commercial stage yet, but a lot of research is being done. In the beginning, the costs of constructing the infrastructure and starting commercial production are high. These costs are likely to decrease in time. [13] Research amidst algae genome is now increasing. It is difficult to get the wanted substances such as oils out of the algae cells. The most typical way to extract oils from algae is to harvest it, dry it out and then collect the oil. However, by this method, new algae needs to be grown again and again. [14] Algae gene manipulating has a great potential, but the laws and attitudes in different countries 4 have to be taken into account. There is a threat that the gene manipulated, fast growing algae spread outside the culture. [12] 5 The current status and the future of algal biofuels Currently, algae are cultivated for food, feed and other purposes. Algal fuel production is only diminutive at the moment as a lot of research needs to be done at first. Centre for management technology has projected that the significant commercial production of algal biofuels will start around 2020 [15]. Since 2007, Neste Oil has studied the potential of algae as a feedstock for their NExBTL diesel. The suitable algae species for NExBTL are the ones which store fat. One aspect in their research is to try to increase the fat production of algae. [12] A significant and less costly option for algal biodiesel production could be producing biogas out of algal oils [16]. 6 References [1] Anonymous, All About Algae, 11 October [2] Anonymous, Advanced Biofuels USA, 8. [3] Anonymous, All About Algae, 11. [4] Anonymous, All About Algae, 11. [5] Anonymous, All About Algae, 11 October 2013 [6] Anonymous, All About Algae, 11 [7] Anonymous, All About Algae, 11 October [8] Anonymous, All About Algae, 11 [9] Anonymous, All About Algae, 11 [10] Anonymous, All About Algae, 11 [11] Anonymous, Algae.Tec Ltd, 11. [12] Salonen, J., Levästä tulevaisuuden polttoainetta, Neste Oil, (1 July 2010). [13] Anonymous, Csiro, Transport/biofuel/Algal-biofuel.aspx, 11 [14] Anonymous, Advanced Biofuels USA, 8. [15] Manninen, L., Uusi ja tehokas öljyntuottaja levät, Taloussanomat, (26 April 2011). [16] Manssila, P., VTT: Levistä polttoainetta ensi vuosikymmenellä, YLE Uutiset, (7 June 2012). 6
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