What is Biofuel?

Are Biofuels Here to Stay? 

Alternative energy sources are becoming more and more popular, creating renewable resources and reducing "greenhouse gases" (CO2 emissions). Biodiesel in the form of FAME (Fatty Acid Methyl Ester) is the most popular petro diesel alternate. It can be used pure in specialized engines, but is usually blended with petro diesel. The percent of biodiesel in the blend is expressed as Bxx, where xx is the percent biodiesel. Up to 5% biodiesel (B5) is common in most markets. When used in such low doses, there is generally no obligation to inform the consumer of its presence in the fuel. In small concentration, it qualifies as an additive. Biodiesel quality has noticeably improved in recent years, but occasional off-specification biodiesel does reach the market. Users of poor quality biodiesel can expect to experience operational issues including internal injector deposits, combustion chamber deposits, sticking of piston rings and fuel filter clogging. 

The end products of the biodiesel or FAME production process are B100 and glycerin (and associated substances). ASTM standards require that the vast majority of the glycerin be removed; but even in very small quantities, it can create big problems for equipment operators. A typical 10,000 gallon (38,000 liter) tanker truck of in spec B5 blended diesel can contain almost a gallon (+/- 3.5 liters) of glycerin (0.240% max %mass, ASTM D6751 B100). It only takes a few spoonful of solidified glycerin to completely disable a fuel filter, starving the engine of diesel and bringing your vehicle to a halt. 
biodiesel chart  

Due to their many advantages over petro-diesel, governments worldwide have become major champions of bio fuels.
Less pollution: Due to its higher oxygen content and lack of “aromatics” and sulfur, biodiesel burns more completely and produces less air pollution than petro diesel. It has been fully tested in compliance with the U.S. Clean Air Act and is required to be used in many municipal and other government vehicles. In addition to being less polluting, it is nontoxic and biodegradable.
Renewable energy source: Reduced reliance on fossil fuels and foreign energy sources is attractive to many nations. 
Economics: The advantages of supporting local economies and agriculture are frequently cited. 
Reduced engine wear: Biodiesel has much better lubricity than petro diesel. In fact, it sometimes eliminates the need for additional lubricity improvers, even in ULSD.
High flash point: makes biodiesel safer to handle. 

Higher cetane number: for faster ignition. 

Along with the advantages of biodiesel, come several potential disadvantages:
Fuel efficiency: Biodiesel has less energy per unit volume than petro diesel. This results in a 3-5% reduction in fuel efficiency and engine power. 

Cold weather performance: Significant filter clogging and injector coking are reported. This can be improved through the use of high quality vegetable oil based biofuels and "winter" blends with cold flow improvers, but it remains an issue in colder climates. 

​Reduced shelf life: Biodiesel oxidizes and goes rancid, just like home cooking oil. This effect is dramatically accelerated by a number of factors including an increased percentage of biodiesel, warm storage temperatures (over 68°F/10°C), water contamination, metals (copper, brass, tin, zinc, lead and bronze) and air contact. We recommend using biofuels within 3 months of production to avoid these problems. 

Higher water content: Biodiesel holds a much greater concentration of water in solution than petro diesel and therefore a greater quantity can fall out as free water when the fuel cools or when it is combined with petro diesel. 

Microbial growth: Higher incidences of microbial growth in fuel tanks have been observed since the use of biofuels became common. Biodiesel is better quality “food” for micro organisms than petroleum. 

Solvent effects: Biodiesel is an aggressive solvent. It is incompatible with certain elastomers (such as Buna Nitrile rubber) and can cause leaking seals in older equipment. New equipment uses different materials to prevent this problem. Also, since it is a solvent, biodiesel will “clean out” fuel tanks of gums and sediments, passing this debris along in the fuel stream. 

Deposits: Engine deposits and clogged injectors are frequently blamed on biodiesel. Much of the time this is caused by lower quality or oxidized biofuels. But even good quality biodiesel can contain certain elements that while soluble in biodiesel, are not soluble in petro diesel. When petro diesel is combined with the bio diesel, these substances can sometimes fall out as soft solids that will plug filters or form deposits. 

Inconsistent quality: Biodiesel production quality issues are much improved from years ago, but there are still isolated incidences of incomplete processing, trace chemicals from the production process or excess water in the fuel. 

Environmental concerns: Ironically, some say that biofuels do more harm than good, driving up food prices and harming the environment in order to produce more crops for fuel stock. Deforestation, risking ecosystems and reducing biodiversity are cited as reasons to cease producing biofuels for transportation purposes.