The world is confronted with the twin crises of fossil fuel depletion and environmental degradation. The indiscriminate extraction and consumption of fossil fuels have led to a reduction in petroleum reserves. Petroleum based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain region of the world. Therefore, those countries not having these resources are facing a foreign exchange crisis, mainly due to the import of crude petroleum oil. Hence it is necessary to look for alternative fuels, which can be produced from materials available within the country. Although vegetative oils can be fuel for diesel engines, but their high viscosities, low volatilities and poor cold flow properties have led to the investigation of its various derivatives. Among the different possible sources, fatty acid methyl esters, known as Biodiesel fuel derived from triglycerides (vegetable oil and animal fates) by transesterification with methanol, present the promising alternative substitute to diesel fuels and have received the most attention now a day. The main advantages of using Biodiesel are its renewability, better quality exhaust gas emission, its biodegradability and the organic carbon present in it is photosynthetic in origin. It does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the green house effect. This paper reviews the source of production and characterization of vegetable oils and their methyl ester as the substitute of the petroleum fuel and future possibilities of Biodiesel production.

Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: A review

Microalgae provide various potential advantages for biofuel production when compared with ‘traditional’ crops. Specifically, large-scale microalgal culture need not compete for arable land, while in theory their productivity is greater. In consequence, there has been resurgence in interest and a proliferation of algae fuel projects. However, while on a theoretical basis, microalgae may produce between 10- and 100-fold more oil per acre, such capacities have not been validated on a commercial scale. We critically review current designs of algal culture facilities, including photobioreactors and open ponds, with regards to photosynthetic productivity and associated biomass and oil production and include an analysis of alternative approaches using models, balancing space needs, productivity and biomass concentrations, together with nutrient requirements. In the light of the current interest in synthetic genomics and genetic modifications, we also evaluate the options for potential metabolic engineering of the lipid biosynthesis pathways of microalgae. We conclude that although significant literature exists on microalgal growth and biochemistry, significantly more work needs to be undertaken to understand and potentially manipulate algal lipid metabolism. Furthermore, with regards to chemical upgrading of algal lipids and biomass, we describe alternative fuel synthesis routes, and discuss and evaluate the application of catalysts traditionally used for plant oils. Simulations that incorporate financial elements, along with fluid dynamics and algae growth models, are likely to be increasingly useful for predicting reactor design efficiency and life cycle analysis to determine the viability of the various options for large-scale culture. The greatest potential for cost reduction and increased yields most probably lies within closed or hybrid closed–open production systems.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2009.0322

Placing microalgae on the biofuels priority list: a review of the technological challenges

Progress in biodiesel processing

Algae biofuels may provide a viable alternative to fossil fuels; however, this technology must overcome a number of hurdles before it can compete in the fuel market and be broadly deployed. These challenges include strain identification and improvement, both in terms of oil productivity and crop protection, nutrient and resource allocation and use, and the production of co-products to improve the economics of the entire system. Although there is much excitement about the potential of algae biofuels, much work is still required in the field. In this article, we attempt to elucidate the major challenges to economic algal biofuels at scale, and improve the focus of the scientific community to address these challenges and move algal biofuels from promise to reality.

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Biofuels from algae: challenges and potential.

Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 1: Pyrolysis systems

Pyrolysis of triglyceride materials for the production of renewable fuels and chemicals.

The primary objective of this work was to study the pyrolytic conversion of fatty acids to produce deoxygenated, liquid hydrocarbon products for use as renewable chemicals or fuels. Stearic acid (n-octadecanoic acid) was chosen as a model compound for the free fatty acids liberated through the hydrolysis of beef tallow. Batch pyrolysis of stearic acid was conducted over a range of temperatures and times, and the reaction products were extracted and identified through gas chromatography and mass spectrometry. Under mild conditions, n-heptadecane was the main product, with concurrent production of CO2, showing that decarboxylation was likely the first reaction to occur. Distinct series of n-alkanes and 1-alkenes developed and shifted to lower carbon numbers with increased temperature and time, consistent with hydrocarbon cracking reactions. Eventually, the series decomposed to aromatics, insoluble solids, and unidentified low-molecular-weight species. Semiquantitative analysis of the chromatographic data co...

Kelly D. Maher

Papers

Pyrolysis of triglyceride materials for the production of renewable fuels and chemicals.

Pyrolytic Decarboxylation and Cracking of Stearic Acid