www.ccsenet.org/jsd Journal of Sustainable Development Vol. 5, No. 4; April 2012 Published by Canadian Center of Science and Education 59 Engine Emissions and Performances with Alternative Biodiesels: A Review A. E. Pillay (Corresponding author) Department of Chemistry, The Petroleum Institute PO Box, 2533, Abu Dhabi, UAE Tel: 971-2607-5417 E-mail: apillay@pi.ac.ae S. C. Fok, M. Elkadi, S. Stephen, J. Manuel, M. Z. Khan & S. Unnithan The Petroleum Institute PO Box, 2533, Abu Dhabi, UAE Received: February 14, 2012 Accepted: March 5, 2012 Published: April 1, 2012 doi:10.5539/jsd.v5n4p59 URL: http://dx.doi.org/10.5539/jsd.v5n4p59 The research is financed by PI-Research Initiation Grant Abstract Smoke opacity, CO, NO x and other engine emissions can vary appreciably with the use of biodiesels obtained from different feedstock. Biofuel density, viscosity and bulk modulus are linked to engine performance and emissions. This paper represents an up-to-date review of engine performances and emissions with biodiesels derived from different feedstock and conventional diesel. The data indicate that biodiesel is an attractive renewable alternative fuel for diesel engines in terms of environmental benefits. Physical and chemical properties of biodiesels can have significant effects on the combustion process, which will impact on the engine performance and emissions. Based on this information, major issues in the search for suitable ingredients and processes to produce quality biodiesels have been presented. The study is of interest to sustainable development. Keywords: Biodiesel, Viscosity, Calorific value, Cetane number, BSFC, Stoichiometric ratios 1. Introduction Interest in biodiesel as an alternative engine fuel has widely increased globally due to political, financial, and environmental reasons. After the oil crisis in the 1970s, many non-oil producing countries initiated efforts to lessen their dependency on fossil fuels by encouraging the development of alternative energy sources such as the production of biodiesel using locally available oil bearing crops. Investors were tempted by the potential returns of investments in these ventures. Feedstock costs constitute the major part of the biodiesel production expenses. By converting unutilized agricultural land to produce high oil-yield crops that are cheap, abundant and can be grown rapidly without restricted growing seasons, analysts believed that the economical production of biofuels for domestic consumption could not only be sustained, but could also be also profitable. This is based on the assumption that the price of biofuels will progressively increase with time owing to the continuous depletion of the limited available fossil fuel reserves and the growing demand for energy. Driven by potential financial gains, the derivation of biodiesels has gained much attention. Extensive research has been conducted on the extraction of biodiesels from different feedstock and the characteristics of biodiesels of different origins on engine performances and emissions have become topics of increasing importance. To date, hundreds of oil bearing crops have been identified. Among them, oils from rapeseed, cottonseed, sunflower, soybean, and palm are generally considered to be among the top contenders for use in diesel engines (Goering et al., 1982). Although these plant oils can be directly used in diesel engines, they are sensitive to cold weather and start to gel as temperature decreases. This causes clogging of filters, sticking of pistons, jamming of valves, rapid wearing and contamination of lubricating oil. One way to overcome these problems is to process the plant oils to biodiesels. Biodiesel can be derived from a variety of animal and vegetable oils (Ozsezen & Canakci, 2010; Buyukkaya, 2010; Aydin & Bayindir, 2010; Celikten et al., 2010; Sayin, 2010; Wu et al., 2009; Lin & Li, 2009; Qi et al., 2009; Lin et al., 2009; Raheman & Ghadge, 2007; Rakopoulos et al., 2006; Usta, 2005; Ilkilic & Yucesu, 2005; Rodjanakid & Charoenphonphanich, 2004; Kalam & Masjuki, 2002; Masjuki et al., 1997;