Biocombustibles

Energy Conversion and Management 50 (2009) 2239–2249

Contents lists available at ScienceDirect

Energy Conversion and Management
journal homepage: www.elsevier.com/locate/enconman

Biofuels securing the planet’s future energy needs
Ayhan Demirbas *
Sila Science, University Mah, Mekan Sok No: 24, Trabzon, Turkey

a r t i c l e

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a b s t r a c t
The biofuels includebioethanol, biobutanol, biodiesel, vegetable oils, biomethanol, pyrolysis oils, biogas, and biohydrogen. There are two global biomass based liquid transportation fuels that might replace gasoline and diesel fuel. These are bioethanol and biodiesel. World production of biofuel was about 68 billion L in 2007. The primary feedstocks of bioethanol are sugarcane and corn. Bioethanol is a gasoline additive/substitute. Bioethanol is by far the most widely used biofuel for transportation worldwide. About 60% of global bioethanol production comes from sugarcane and 40% from other crops. Biodiesel refers to a diesel-equivalent mono alkyl ester based oxygenated fuel. Biodiesel production using inedible vegetable oil, waste oil and grease has become more attractive recently. The economic performance of abiodiesel plant can be determined once certain factors are identified, such as plant capacity, process technology, raw material cost and chemical costs. The central policy of biofuel concerns job creation, greater efficiency in the general business environment, and protection of the environment. Ó 2009 Elsevier Ltd. All rights reserved.

Article history: Received 24 September 2008 Accepted 16 May2009 Available online 16 June 2009 Keywords: Biofuel Bioethanol Biodiesel Economic and environmental impacts

1. Introduction Liquid biofuels such as bioethanol and biodiesel may offer a promising alternative [1–3]. Because of increase in petroleum prices especially after petrol crisis in 1973 and then gulf war in 1991, geographically reduced availability of petroleum and more stringentgovernmental regulations on exhaust emissions, researchers have studied on alternative fuels and alternative solution methods [4–6]. The use of biofuels decreases the external energy dependence, promotion of regional engineering, increased R&D, decrease in impact of electricity production and transformation; increases the level of services for the rural population, creation of employment, etc. [7–9]. Theterm biofuel or biorenewable fuel (refuel) is referred to as solid, liquid or gaseous fuels that are predominantly produced from biomass [10–17]. Liquid biofuels being considered world over fall into the following categories: (a) bioalcohols [18–21], (b) vegetable oils [22–24] and biodiesels [25–27]; and (c) biocrude and synthetic oils [28–37]. Biofuels are important because they replace petroleumfuels. It is expected that the demand for biofuels will rise in the future. Biofuels are substitute fuel sources to petroleum; however, some still include a small amount of petroleum in the mixture [38,39]. Biofuels are generally considered as offering many priorities, including sustainability, reduction of greenhouse gas emissions, regional development, social structure and agriculture, securityof supply [40–43].

* Tel.: +90 462 230 7831; fax: +90 462 248 8508. E-mail address: ayhandemirbas@hotmail.com 0196-8904/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2009.05.010

Today bioethanol is the most used non-fossil alternative engine fuel in the world. The choice of raw material depends on local conditions. Bioethanol is good alternate fuel thatis produced almost entirely from food crops. The primary feedstock of this fuel is corn. An important advantage of crop-based ethanol is its greenhouse benefits [18,28]. Due to the increasing concern on environmental protection, numerous researches on the usage of biodiesel are carried out in recent years. Biodiesel has become more attractive recently because of its environmental benefits...