Because biodiesel and green diesel are both made from organic matter, many people think the two are the same. You can’t get any further from the truth with such an opinion. One major difference between the two is the manufacturing process. The varying processes lead to major distinctions in the chemical composition of the two fuels. Green diesel resembles petro diesel in its chemical composition. Biodiesel, on the other hand, is an ester with significantly different characteristics.
What is Green Diesel?
Green diesel, also referred to as renewable or second generation diesel, is processed from recently living organisms. There are three processes used to process green diesel; thermal conversion, hydro treatment, and biomass to liquid.
The green diesel process simply aims at removing impurities from the raw material and introducing hydrogen to the chemical structure of the substance. This significantly improves the quality of the fuel. The chemical composition of green diesel is similar to that of petro diesel, even though it is made from organic matter. Using green fuel significantly reduces greenhouse gas emissions, and is more environmentally-friendly compared to biodiesel. Besides, it burns more efficiently and has cleaner emissions.
Green diesel can be used in all diesel engines with no modifications whatsoever. It can also be utilised in high concentrations. With this type of fuel, there is no risk of microbial growth since it is free of impurities. It will, therefore, not cause any damage to the fuel system of an engine.
What is Biodiesel Fuel?
Biodiesel fuel, also known as fatty acid methyl ester (FAME), is also produced from organic matter. The biodiesel fuel source is vegetables, and animal fats and oils. Its production process involves transesterification of fats and oils with methanol or ethanol. Ethanol is commonly used in this process since it is cheap.
Unlike green diesel, the resulting chemical is a mono-alkyl ester. The chemical also contains oxygen atoms, which is not the case with green diesel. Again, unlike green diesel, biodiesel can only be used in diesel engines blended with diesel. This is because it is an ester. Very high concentrations of biodiesel fuel can lead to the damage of fuel systems and can also result in the excessive buildup of carbon in diesel engines. The blend percentage is not uniform across countries, and in the USA for example, diesel-powered vehicles are only allowed to use a 20 percent blend of biodiesel fuel. In Europe, biomass is limited to a maximum concentration of 7 percent.
The use of some biodiesel fuels necessitates frequent maintenance processes and creates a continuous need for oil changes. This does not occur with green energy.
A major issue with biodiesel fuel is its tendency to freeze at very low temperatures. That means you cannot use it to power your vehicle in winter or other cold periods of the year. The temperature at which biodiesel freezes is also not constant as it depends on the type of oil or fat that was used to process the fuel. Most characteristics of biodiesel in cold weather are measured using the cloud point, the cold filter plugging point, and the pour point.
The pour point is considered to be the lowest temperature at which there is movement in the car’s diesel engine. On the other hand, the cold filter plugging point of the fuel is that temperature at which its crystals start clogging the fuel filter plugs and the water pump set. With biodiesels, there is a very small gap between the cold filter plugging point and pour point, and the engine will usually break down at very low temperatures.
On the other hand, green diesel is very high in quality. That means it can withstand very low temperatures without leading to the breakdown of a vehicle. Unlike biodiesel, it can be used in very high concentrations with no risk of damage to the fuel filter plugs of the car.
Biodiesel fuel offers less energy per unit volume as compared to green diesel. With biodiesel fuel, the engine power is usually around 4 percent lower. In addition, biodiesel has lower fuel efficiency compared to green diesel.
Engine performance with biodiesel is further affected by the deposits and clogging of the engine. This is because many biodiesels are low in quality; and so, get oxygenated very easily. On the other hand, green diesel does not crystallise, and there is, therefore, no risk of clogging the engine.
Although both biodiesel and green diesel are made from organic matter, the two have very different characteristics. Green diesel is better at fuel efficiency and is generally more environmentally-friendly compared to biodiesel. In addition, the engine performs at its peak when running with green diesel. In cold weather, biodiesel fuel tends to freeze, and this leads to the breakdown of the car’s engine. Green diesel, being of very high quality, can run even under the lowest of temperatures.
Natural Fuel. 2015. How to Store Biodiesel. [ONLINE] Available at: http://naturalfuel.com.au/how-to-store-biodiesel/. [Accessed 29 May 2017].
Diesel Parts and Services. 2015. DIESEL ENGINES AS AN ECO-FRIENDLY OPTION. [ONLINE] Available at: http://dieselparts.com.au/blog/diesel-engines-as-an-eco-friendly-option/. [Accessed 29 May 2017].
Penn State Extension. 2016. Using Biodiesel Fuel in Your Engine. [ONLINE] Available at: http://extension.psu.edu/natural-resources/energy/biofuels/factsheets/using-biodiesel-fuel-in-your-engine. [Accessed 29 May 2017].