CHAPTER ONE
INTRODUCTION
There is a need for alternative energy sources to petroleum-based fuels due to the depletion of the worlds’ petroleum reserves,global warming and environmental concerns. American standard testing and materials defined biodiesel as a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable vegetable oils or animal fats and meets the requirements of ASTM 6751(ASTM, 2008). Ozone depletion,global warming,greenhouse gases concerns have promoted biodiesel as an alternative renewable and eco-friendly fuel.The concept of biofuel is notnew. Rudolph Diesel was the first to use a vegetable oil(peanut oil) in a diesel engine in 1911(Akoh et al ., 2007 ; Antczak et al., 2009). The use of biofuels in place of conventional fuels would slow the progression of global warming by reducing sulphur,carbon oxides and hydrocarbon emissions (Fjerbaek et al., 2009). Because of its high viscosity and low volatility, the direct use of vegetable oil in diesel engines can cause problems including;high carbon deposits,scuffing of engine liner,injection nozzle failure,gum formation,lubricating oil thickening,high cloud and pour point (Fukuda et al., 2001; Murugesan et al.,2009). In order to avoid these problems, the feedstock is chemically modified to its derivatives which have properties more similar to conventional diesel (Fukuda et al., 2001).Transesterification is the process by which biodiesel is produced,in this process vegetable oil reacts with an alcohol(methanol) to form methyl ester (biodiesel) and another alcohol (glycerol) with NaOH as catalyst (Pinto et al., 2005). Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.
In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17% from 2009, and biofuels provided 2.7% of the world’s fuels for road transport, a contribution largely made up of ethanol and biodiesel. Global ethanol fuel production reached 86 billion liters (23 billion gallons US) in 2010, with the United States and Brazil as the world’s top producers, accounting together for 90% of global production. The world’s largest biodiesel producer is the European Union, accounting for 53% of all biodiesel production in 2010. As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states or provinces. The International Energy Agency has a goal for biofuels to meet more than a quarter of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal.There are various social, economic, environmental and technical issues relating to biofuels production and use, which have been debated in the popular media and scientific journals. These include: the effect of moderating oil prices the “food vs fuel debate, poverty reduction potential, carbon emissions levels, sustainable biofuel production, deforestation and soil erosion loss of biodiversity and impact on water resources (Mc Carthy et al., 2011).
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuelconsisting of long-chain alkyl (methyl, ethyl, or propyl) esters. Biodiesel is typically made by chemically reacting lipids(e.g., vegetable oil, animal fat (tallow) with an alcohol producing fatty acid esters (Fletcher et al., 2011). Biodiesel is meant to be used in standard diesel engines and is thus distinct from the vegetable and waste oils used to fuel converted diesel engines. Biodiesel can be used alone, or blended with petrodiesel in any proportions. Biodiesel can also be used as a low carbon alternative to heating oil (Monyem and Van Gerpen, 2001).
1.1.Blends
Blends of biodiesel and conventional hydrocarbon-based diesel are products most commonly distributed for use in the retail diesel fuel marketplace (Demirbas, 2007). Much of the world uses a system known as the “B” factor to state the amount of biodiesel in any fuel mix:
- 100% biodiesel is referred to as B100
- 20% biodiesel, 80% petrodiesel is labeled B20
- 5% biodiesel, 95% petrodiesel is labeled B5
- 2% biodiesel, 98% petrodiesel is labeled B2
