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Demirbas M.F.,Sila Science
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2010

Microalgae have long been recognized as potentially good sources for biofuel production because of their high oil content and rapid biomass production. The oil productivity of many microalgae exceeds the best producing oil crops. In recent years, use of microalgae as an alternative biodiesel feedstock has gained renewed interest from researchers, entrepreneurs, and the general public. Biodiesel produced from microalgae is being investigated as an alternative. The lipid and fatty acid contents of microalgae vary in accordance with culture conditions. The average fatty acid contents of the algal oils are 36% oleic (18:1), 15% palmitic (16:0), 11% stearic (18:0), 8.4% iso-17:0, and 7.4% linoleic (18:2). © Sila Science.


Balat H.,Sila Science
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2010

The purpose of this study is to discuss present challenges and future prospects for production and use of biofuels as alternative energy pathways to sustainable development. The dramatic increase in the price of petroleum, the finite nature of fossil fuels, increasing concerns regarding environmental impact, especially related to greenhouse gas emissions, and health and safety considerations are forcing the search for new energy sources and alternative ways to power the world's motor vehicles. Interest in the use of biofuels worldwide has grown strongly in recent years due to the high oil prices, concerns about climate change from GHG emissions and the desire to promote domestic rural economies. Developing countries have a comparative advantage for bio-fuel production because of greater availability of land, favorable climatic conditions for agriculture and lower labor costs. In developed countries there is a growing trend towards employing modern technologies and efficient bio-energy conversion using a range of bio-fuels, which are becoming cost-wise competitive with fossil fuels. © Sila Science.


Balat M.,Sila Science
Energy Sources, Part A: Recovery, Utilization and Environmental Effects | Year: 2010

This article presents a detailed review of thermochemical routes for hydrogen production from biomass as a renewable and alternative energy source. Hydrogen is currently derived from non-renewable natural gas and petroleum, but could, in principle, be generated from renewable resources such as biomass. The production of hydrogen from fossil fuels causes the co-production of CO2, which is assumed to be the main factor responsible for the so-called greenhouse effect. The production of hydrogen from biomass has several advantages compared to that of fossil fuels. The methods available for hydrogen production from biomass can be divided into two main categories: thermochemical and biological routes. Hydrogen can be produced from biomass by pyrolysis, gasification, steam gasification, and steam-reforming of bio-oils. Copyright © Taylor & Francis Group, LLC.


Demirbas A.,Sila Science
Energy Sources, Part A: Recovery, Utilization and Environmental Effects | Year: 2010

In this study, the effect of temperature on the yield of hydrogen from two mosses (Polytrichum commune and Thuidium tamarascinum) and two algae (Cladophora fracta and Chlorella protothecoid) by pyrolysis and steam gasification were investigated. In each run, the main components of the gas phase were CO2, CO, H2, and CH4. The yields of hydrogen by pyrolysis and steam gasification processes of the samples increased with temperature. The yields of gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 5.3 to 40.6%, 6.5 to 42.2%, 8.2 to 39.2%, and 9.5 to 40.6% by volume, respectively, while the final pyrolysis temperature was increased from 575 to 925 K. The percent of hydrogen in gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 21.3 to 38.7%, 23.0 to 41.3%, 25.8 to 44.4%, and 27.6 to 48.7% by volume, respectively, while the final pyrolysis temperature was increased from 650 to 875 K. The percent of hydrogen in gaseous products from the samples of Polytrichum commune, Thuidium tamarascinum, Cladophora fracta, and Chlorella protothecoides increased from 21.8 to 50.0%, 23.5 to 52.0%, 26.3 to 54.7%, and 28.1 to 57.6% by volume, respectively, while the final gasification temperature was increased from 825 to 1,225 K.


Demirbas M.F.,Sila Science
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2011

Scenarios are important tools for long term planning and policy settings. Renewable energy is a promising alternative solution because it is clean and environmentally safe. Approximately, half of the global energy supply from renewables in 2040. Photovoltaic (PV) systems and wind energy will be able to play an important role in the energy scenarios of the future. The most significant developments in renewable energy production are observed in photovoltaics (from 0.2 to 784 million ton oil equivalent, Mtoe) and wind energy (from 4.7 to 688 Mtoe) between 2001 and 2040. Geothermal and solar thermal sources are more important energy sources in future. PV will then be the largest renewable electricity source with a production of 25.1% of global power generation in 2040. Gasoline, LPG, methanol, ethanol and natural gas can be converted to electricity via fuel cell. The law generation of energy from renewable resources has been accepted on December 29, 2010. New law also aims to encourage domestic production in the systems that using renewable energies for producing electrical energy. © Sila Science.


Balat M.,Sila Science
Energy Sources, Part A: Recovery, Utilization and Environmental Effects | Year: 2011

The aim of this article is to discuss the properties of pyrolysis liquid products and their primary applications. The pyrolysis of biomass is a promising route for the production of solid (charcoal), liquid (tar and other organics), and gaseous products. These products are of interest as they are possible alternate sources of fuels and chemicals. Pyrolysis liquid is referred to in the literature by terms, such as pyrolysis oil, bio-oil, bio-crude oil, bio-fuel oil, wood liquid, wood oil, liquid smoke, wood distillates, pyroligneous tar, and pyroligneous acid. Bio-oil from biomass pyrolysis mainly consisted of aromatic, aliphatic, and naphthenic hydrocarbons and oxygenated compounds, such as phenols, furans, alcohols, acids, ethers, aldehydes, and ketones. Bio-oil has a higher energy density than biomass, can be readily stored and transported, and can be used either as a renewable liquid fuel or chemical production. Copyright © Taylor & Francis Group, LLC.


Demirbas B.,Sila Science
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2011

Biomass upgrading processes include fractionation, liquefaction, pyrolysis, hydrolysis, fermentation, and gasification. Refined bio-oil from biomass pyrolysis can be used in vehicle engines as fuel. Bioethanol and biodiesel are two competing liquid biofuels with gasoline and diesel. The biofuels can be obtained from biomass materials by biomass thermochemical and biochemical conversion methods. Sound economic and technical design is needed to make sustainable biomass-toenergy business and realise successfully operated bioenergy systems. The right strategy to successful business includes sustainable developing processes. © Sila Science.


Balat M.,Sila Science
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2011

Biodiesel is an alternative to petroleum-based fuels derived from vegetable oils, animal fats, and used waste cooking oil including triglycerides. At present, the high cost of biofuels is the major obstacle to their commercialization. Biodiesel production costs are highly dependent on feedstock prices, with feedstock representing approximately 70% to 95% of the finished product cost. One major problem with biodiesel production is the availability of raw materials for the production. More than 95% of global biodiesel production is made from edible vegetable oils. However, extensive use of vegetable oils may cause other significant problems such as starvation in developing countries. © Sila Science.


Demirbas M.F.,Sila Science
Energy Education Science and Technology Part A: Energy Science and Research | Year: 2012

Transesterifications of vegetable oils in supercritical methanol are carried out without using any catalyst. Anchovy oil was transesterified with supercritical methanol to produce biodiesel. The most important variables affecting the methyl ester yield during the transesterification reaction are molar ratio of alcohol to vegetable oil and reaction temperature. The viscosity values of anchovy oils are between 20.18 and 25.38 mm 2/s whereas those of anchovy oil methyl esters are between 4.16 and 4.48 mm 2/s. © Sila Science.


Demirbas M.F.,Sila Science
Energy Education Science and Technology Part B: Social and Educational Studies | Year: 2011

After the year 2037, it is believed that the Otto and Diesel engines will replace the electric motors. Electric vehicles will work with hydrogen and fuel cells. The vehicles running on batteries and fuels are called hybrid electric vehicles. The cars with hybrid engines promise great hope for the future. The use of foodstuffs as raw materials for energy production, such as ethanol from corn, increases the prices of meat and milk. The drought and soil infertility increases the risk of human and animal nutrition. The rise in the production of biofuels based on food grains has contributed to global food price increases since 2006. The global food crisis is hitting with alarming speed and force, challenging the USA, other nations. The root causes of the global food crisis are complex, fluid, persistent, and multidimensional. This is not a simple problem. For this purpose a food using protocol must be organized with broad participation. © Sila Science.

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