Using biodiesel fuel as of 2011 has typically centered around the farming and construction industries. This means that biodiesel equipment like heavy-duty pickup trucks, tractors, and forestry equipment like grapple skidders and harvesters have typically had a steady demand for biodiesel fuel. Any diesel engine, however, can be run on biodiesel fuel, so the increasing trend among types of biodiesel equipment involve the consumer truck and car fleet as well as aircraft and boats. The industry also supplies large amounts of fuel for biodiesel equipment not involved in transportation, construction, or recreation as well, including using it to run electrical generators and as a direct source of heating fuel for buildings.
Worldwide, biodiesel production has been on a steady increase since 2004 due to the advantages that it offers as an alternative energy source. In 2004, estimates are that 2,800,000 tons of biodiesel fuel were generated globally, and, by 2008, that number had risen to 11,100,000 tons of fuel being produced with production capacity rising even higher, to a potential to produce 32,600,000 tons a year. As of 2009, projections are that the global demand for biodiesel fuel will double again in five more years, with 30 countries currently in the business of manufacturing the fuel. Europe has seen one of the fastest growth rates for the use and production of biodiesel fuel, with about a 600% increase in actual production of the fuel between 2002 and 2007 and a 1,200% increase in the continent's raw ability to produce the fuel during the same time period.
The main disadvantage of biodiesel equipment is that it was often previously run by petroleum-based diesel that leaves a deposit of wax and heavier compounds behind in fuel lines and engines over time. The biodiesel fuel will dissolve these compounds and carry them to fuel filters, where the filters then become clogged. Over long periods of time, biodiesel fuel can also cause rubber hoses or seals to begin to break down, though automotive engines manufactured after the 1980s period have improved rubber compounds that don't demonstrate this problem.
The primary advantages of biodiesel are that it produces less pollution than petroleum-based fuels do and it can be a renewable energy resource harvested from otherwise waste byproducts. It generates roughly the same amount of energy as traditional diesel fuel and doesn't require any extensive engine modifications to be used. It can also serve as a local energy source, especially for farms where it can be produced on site, which eliminates the need to truck fuel around from great distances. A wide variety of plant sources can be used to produce it as well, from soybean oil to hemp oil and oil harvested from sunflower seeds.
The primary chemical component of biodiesel fuel is a fatty acid methyl ester. This is refined from virgin plant oils from crops such as avocados, pecans, or rapeseed and canola-based oils, or recycled waste plant oils from commercial food and other industrial processes. In the US alone, it is estimated that 5,000,000,000 gallons (19,000,000,000 liters) of waste cooking oil are produced annually as of 2006 by restaurants, which could all be converted to biodiesel fuel.
The methodology for making biodiesel can be repeated on a hobby basis, but government standards also exist in the US and Europe to generate reliably formulated compounds for the commercial market labeled as B2, or B5 and B7 biodiesel used for the consumer auto and truck fleet. The B10 mixture, for instance, used by heavy-duty logging equipment, conforms to American Society for Testing Materials (ASTM) D7467 specifications. Converting waste oil to usable fuel in biodiesel equipment requires a four-step process of esterification, transesterification, a settling period, and a washing period. The first two steps involve chemical reactions with sulfuric acid and catalysts like sodium hydroxide to separate the methyl ester compound from fatty acids like glycerol, which is then removed along with impurities in the settling and washing processes.
