Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO 2 , wastewater treatment, in human health, as food additive, and for aquaculture.

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Microalgae for biodiesel production and other applications: A review

Biodiesel is gaining more and more importance as an attractive fuel due to the depleting fossil fuel resources. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst. The process of transesterification is affected by the mode of reaction condition, molar ratio of alcohol to oil, type of alcohol, type and amount of catalysts, reaction time and temperature and purity of reactants. In the present paper various methods of preparation of biodiesel with different combination of oil and catalysts have been described. The technical tools and processes for monitoring the transesterification reactions like TLC, GC, HPLC, GPC, 1H NMR and NIR have also been summarized. In addition, fuel properties and specifications provided by different countries are discussed.

Technical aspects of biodiesel production by transesterification—a review

http://aoatools.aua.gr/pilotec/files/bibliography/Biofuels%20(alcohols%20and%20biodiesel)%20applications%20as%20fuels%20for%20internal-4026835713/Biofuels%20(alcohols%20and%20biodiesel)%20applications%20as%20fuels%20for%20internal.pdf

Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines

A review on biodiesel production using catalyzed transesterification

Biodiesel processing and production

Biodiesel is an alternative fuel for diesel engines consisting of the alkyl monoesters of fatty acids from vegetableoils or animal fats. Most of the biodiesel that is currently made uses soybean oil, methanol, and an alkaline catalyst. The highvalue of soybean oil as a food product makes production of a costeffective fuel very challenging. However, there are largeamounts of lowcost oils and fats such as restaurant waste and animal fats that could be converted to biodiesel. The problemwith processing these low cost oils and fats is that they often contain large amounts of free fatty acids (FFA) that cannot beconverted to biodiesel using an alkaline catalyst. In this study, a technique is described to reduce the free fatty acids contentof these feedstocks using an acidcatalyzed pretreatment to esterify the free fatty acids before transesterifying the triglycerideswith an alkaline catalyst to complete the reaction. Initial process development was performed with synthetic mixturescontaining 20% and 40% free fatty acids, prepared using palmitic acid. Process parameters such as the molar ratio of alcohol,type of alcohol, acid catalyst amount, reaction time, and free fatty acids level were investigated to determine the best strategyfor converting the free fatty acids to usable esters. The work showed that the acid level of the high free fatty acids feedstockscould be reduced to less than 1% with a 2step pretreatment reaction. The reaction mixture was allowed to settle betweensteps so that the watercontaining alcohol phase could be removed. The 2step pretreatment reaction was demonstrated withactual feedstocks, including yellow grease with 12% free fatty acids and brown grease with 33% free fatty acids. After reducingthe acid levels of these feedstocks to less than 1%, the transesterification reaction was completed with an alkaline catalystto produce fuelgrade biodiesel.

/pdf/biodiesel-production-from-oils-and-fats-with-high-free-fatty-2vjopw370u.pdf

Biodiesel production from oils and fats with high free fatty acids

Vegetable oils and animal fats can be transesterified to biodiesel for use as an alternative diesel fuel.
Conversion of low cost feedstocks such as used frying oils is complicated if the oils contain large amounts of free fatty
acids that will form soaps with alkaline catalysts. The soaps can prevent separation of the biodiesel from the glycerin
fraction. Alternative processes are available that use an acid catalyst. The objective of this study was to investigate the
effect of process variables on acid-catalyzed transesterification. The molar ratio of alcohol, reaction temperature, catalyst
amount, reaction time, water content, and free fatty acids were investigated to determine the best strategy for producing
biodiesel. Food grade soybean oil was used to prepare esters using excess methanol and sulfuric acid as a catalyst. To
compare the effect of different alcohol types on ester formation, methanol, ethanol, 2-propanol, and n-butanol were
compared. The American Oil Chemists’ Society Method Ca 14-56 was used to measure the biodiesel’s total glycerin
amount as an indicator of the completeness of the reaction. It was found that acid catalysis can provide high conversion
rates but much longer times are required than for alkaline catalysts. The acid catalyst also requires the concentration of
water to be less than 0.5%, which is about the same as is required for alkaline catalysts. Water formed by the
esterification of free fatty acids limited their presence in the oil to 5%.

Biodiesel production via acid catalysis

https://seniordesign.engr.uidaho.edu/2007_2008/frenchfryfuel/Biodiesel%20from%20WVO%20Mustafa%20Canakci.pdf

The potential of restaurant waste lipids as biodiesel feedstocks.

Biodiesel, which is a new, renewable and biological origin alternative diesel fuel, has been receiving more attention all over the world due to the energy needs and environmental consciousness Biodiesel is usually produced from food-grade vegetable oils using transesterification process Using food-grade vegetable oils is not economically feasible since they are more expensive than diesel fuel Therefore, it is said that the main obstacle for commercialization of biodiesel is its high cost Waste cooking oils, restaurant greases, soapstocks and animal fats are potential feedstocks for biodiesel production to lower the cost of biodiesel However, to produce fuel-grade biodiesel, the characteristics of feedstock are very important during the initial research and production stage since the fuel properties mainly depend on the feedstock properties This review paper presents both biodiesel productions from various feedstocks and their effects on the fuel properties

Mustafa Canakci

Papers

Biodiesel production from oils and fats with high free fatty acids

Biodiesel production via acid catalysis

The potential of restaurant waste lipids as biodiesel feedstocks.

Biodiesel production from various feedstocks and their effects on the fuel properties.

Determination of the density and the viscosities of biodiesel–diesel fuel blends