Algal Biotechnology for Fuel Applications

The purpose of writing this book is to justify the production of biofuels from algae to minimize the emissions of fossil fuel technologies to reduce their environmental effects. Moreover, the use of algae, to reduce the amount of CO2 emissions from the global CO2 cycle is an alternative to existing biomass conversion technologies. The book covers the most efficient algae-to-oil conversion technologies, fuel characterization, and their reflection on different technologies. It is our hope that the topics here will not only help the scientific community for a more thorough understanding of alternatives to fossil fuels but also the civil society at large as well as policymakers at national and international level.

Biogas is produced with an anaerobic method, which involves live digestion of biomass in an oxygen-free environment. The second part of our book gives information about algae technology of the anaerobic process, which produces biogas by a biological process using animal fertilizers, food waste, and bioenergy products. In general, biogas can be used to produce heat and electricity, and its addition to the natural gas network is even considered as a vehicle fuel. It consists of 30-40% CO2 as content, 45-65% CH4. Conversion of CH4, which is 20 times more harmful than CO2 as a greenhouse gas, into energy is essential for the protection of environmental impact. In this sense, the burning of biogas emerges as a greenhouse gas reduction strategy.

Large amounts of residues are obtained after lipid extraction when producing biodiesel from microalgae. From these residues, animal feed or bioethanol production may be obtained. Another alternative biofuel that can be obtained from microalgae biomass residues is bio-oil from pyrolysis or hydrothermal processes. Out of these, microalgae for biofuel production stand out due to the high thermal value of Algal biomass of around 24 MJ / kg. The organic components of the biological mass can be thermally decomposed in the production of fuel by thermochemical applications, such as direct combustion, gasification, pyrolysis, and liquefaction. With the hydrothermal liquefaction process, microalgae are converted into liquid crude oil with or without a catalyst. The reaction takes place at 280-370 °C and 10-25 MPa pressure on wet biomass in water. Biological oil production by hydrothermal liquefaction method from microalgae has gained considerable attention in recent years. Compared to the biodiesel obtained mainly due to the lipid content, hydrothermal liquefaction converts not only the lipid content but also carbohydrates and proteins.

In this study, biodiesel production was investigated by the transesterification reaction from algae oil. For biodiesel production, the oil obtained from Chlorella protothecoides type algae grown in freshwater with 5% thermal water was added to fully automated closed-loop system high-tech pyramid photobioreactors and adapted for oil production, which had a low acid value (0.23 mg KOH/g). Because of this, base catalyst transesterification was applied. For the transesterification reaction, 99.7% purity of methyl alcohol as alcohol and 99.9% purity of potassium hydroxide (KOH) was used as a catalyst. In order to determine the most suitable conditions for the production of biodiesel from algae oil, a series of laboratory-scale preliminary experiments have been carried out. As a result of the optimization studies, the 6:1 methyl alcohol/oil molar ratio, the use of KOH up to 0.75% of the oil by mass, the reaction temperature of 60 °C, and the reaction time of 60 minutes were determined as the most suitable conditions for biodiesel production. Under these conditions, 96.4% methyl ester yield was obtained, and kinematic viscosity and density values of the final biodiesel product were measured as 4.493 mm2/s and 882 kg/m3. As a result of the physical and chemical analysis of the produced biodiesel, it has been determined that it has an ester content of over 96% and that the free and total glycerol content with methanol, mono-, di- and tri-glyceride is well below the maximum values specified in the EN 14214 and ASTM 6751 biodiesel standards. However, properties such as viscosity, density, flash point, cetane number, acid value, sulfur and water content were found to be compatible with the specified standards. In addition, besides having the standard fuel properties of the produced biodiesel, its high cetane number (57) and good cold filter clogging point (-11 oC), makes it an important alternative diesel engine fuel.

Algae have been produced or evaluated as a nutritional supplement in animal husbandry, rather than as an alternative energy source for many years. As a result of biomass energy research, which has accelerated in recent years with the impact of rising oil prices, algae have started to be seen as a promising energy source. Despite being successful in laboratory research, pilot, and small-scale experiments, also called third-generation biofuel technologies and aiming to use many algae species in nature as an energy source, the desired yield cannot be obtained if ideal processes cannot be created in large-scale local productions. In general, algae may contain about 15-77% fat although the volume varies by species. Compared to other oil plants, their high oil content and growth efficiency make algae attractive for biodiesel and biogas production. The production of these fuels from algae has the potential to respond to the increasing global energy need and, in part, to contribute to the prevention of global warming by converting more than enough carbon dioxide in the atmosphere into efficient products through photosynthesis.

The purpose of this book chapter is to provide general information regarding microbial fuel cell (MFC) systems, an important type of fuel cell of environmentally friendly energy conversion systems as an alternative to fossil fuel technologies. Besides, it is one of the main motivations of this study to include the academic literature on microbial fuel cells, which is a very popular field of study in recent years. In this context, the history, principles, and different approaches of MFCs are discussed. After that, the materials (anode, cathode, membrane, etc.) that make up the system are examined. Finally, different types of microbial fuel cells that can be varied by material design are discussed and presented.

Since algae are simple organisms that contain chlorophyll, they can be found anywhere on earth where they can use light for photosynthesis. Although pool-type open systems are generally used, closed photobioreactors are also used in the cultivation of algae. The low investment and operating costs of the outdoor pools made the system preferable in the industry. However, the difficulty of controlling the production conditions and the risk of contamination appears as the disadvantages of the system. It is necessary to compare fundamental aspects such as effective use of light in large-scale culture systems, temperature, hydrodynamic balance in algae culture, and maintaining the continuity of the culture. The ideal growth of each algae species takes place in culture media with its specific conditions. For example, Spirulina grows best at high pH and bicarbonate concentration, Chlorella in nutrient-rich media, and Dunaliella salina at very high salinity.

Since MFC degrades simple carbohydrates i.e. glucose, acetate, and butyrate, and countless organic substances such as pig wastewater, domestic wastewater, and manure sludge waste, the biochemical energy generated by the catalytic reactions of microorganisms and converts the waste produced into energy. It promises a sustainable wastewater treatment to balance the operating cost. This chapter is a review of the advantages of microbial fuel cell treatment of food industry wastewater, which creates high organic pollution in the industrial field.

It is well known that the use of algae-based fuels is not widespread as they do not meet the necessary fuel standards. The amount of oil products obtained from traditional biomass sources exceeds that obtained from algae. However, ecology can provide more assistance in increasing the current efficiency of oil production from algae. Depending on the species, effective results can be obtained through the production of fatty acids and biofuels. The amount of fuel produced by a single species should be weighted against the amount of oil produced by a combination of species. The presence of genetic diversity, particularly in two types of algae mixtures, is unavoidable in order to improve the quality of fuel produced. The lipid obtained under genetically diverse population is highlighted in this study.

Energy is becoming one of the most expensive production inputs nowadays. Energy reserves are starting to run out and their polluting effects have been seen around the world. Therefore, there is an urgent need for renewable energy sources instead of fossil fuels. One of these energy sources is algae biomass, which is seen as promising for biofuel production.

The oil yield of many microalgae species varies. Therefore, the selection of algae species is important. Features that are effective in selecting the appropriate species for algae production are growth and productivity, minimum contamination, and easy harvesting. However, the percentages of carbohydrate, fat, and protein in the structure of algae provide preliminary information about the oil yield to be obtained from that algae species.

Microalgae, which are considered to be the living group that uses water and solar energy most effectively, have attracted the attention of researchers. Researches on efficient production of microalgae from starter cultures in the laboratory environment to outdoor ponds and photobioreactors continue in many countries. In addition to the known microalgae species, studies to search for new microalgae species that are rich in nutrient content and ease of production are ongoing. Of course, the researches also include more economical algae production studies. Algae and algae produced as larval food in aquaculture can be used as food support, as well as in the production of nutraceuticals and pharmaceuticals, like food coloring, soil fertilizer, and plant diseases. Algal oils and algal biomass have been gaining interest in renewable energy sources, especially in recent years, and studies in this area continue. The implementation of all these issues is based on well-known algal physiology and the realization of successful algae cultures.

CO2, which is a gas produced as a result of combustion, has an important share in greenhouse gases such as SOx, CO, and NOx and causes global warming. As biodiesel produced from algae converts CO2 within the biological carbon cycle, it accelerates the carbon cycle, as a result of which the greenhouse gas effect decreases. C16-C18 methyl esters in biodiesel whose degradability feature resembles dextrose (sugar) do not show any negative microbiological affect up to 10000 mg/L, they decompose rapidly in nature. 40% of diesel in water and 95% of biodiesel in 28 days can be degraded. In the production of biodiesel, catalysts that break the triglyceride bonds allow the esters to become free.

This chapter provides basic economic information that readers will need during the operation phase before establishing any algae business. The subject has been reinforced with simple examples.

In order to better evaluate the water potential of our world, we will now take a look at the various aquatic products that have had a significant impact on the biotech industry, from research materials to nutritional additives.