What is the difference between biodiesel and fossil diesel

Failure to activate ADP-glucose pyrophosphorylase in a pseudomonas starch-free mutant resulted in triacylglycerol being 10 times higher, indicating that sharing of photosynthetic carbon partition from starch to triacylglycerol synthesis may be more successful than lipid synthesis pathway manipulation against triacylglycerol overproduction [ 41 ].

The Synechococcus elongatus is capable of producing butanol directly from CO 2 by altering the coA-dependent 1-butanol process pathway to cyanobacterium [ 42 , 43 ]. Any biodiesel or green diesel may be similar to the original biomass oils. Hydro-treated oil is a high-quality, sulphur-free diesel with a very large proportion of Cetane 88—95 [ 47 ]. As glycerine is a co-product of the latter process, the net yield of hydrolysed organic oils is much higher than that of the esterification reaction.

Oil refiners use hydrolysis to eliminate impurities through the treatment of gaseous hydrogen feed [ 48 ]. Some chemical reactions are improved by the use of solid catalysts, product selectivity is improved and total hydrogen consumption is optimised [ 49 ]. Hydrolysis process involves heat and pressure and ultimately reduces the molecular weight of the feed [ 50 ]. In triglyceride-containing oils, four hydrocarbon molecules, for example, are reduced by propane molecules and three hydrocarbon molecules under hydrotreatment [ 51 ] in the range C12—C Green diesel processing includes the hydrogenation of triglycerides for the removal of metals, oxygen and nitrogen compounds by the current refinery [ 52 ].

These diesels which can be used for production by dedicated hydro-treatment plants do not use conventional fuel. As a result, the investment cost of developing this renewable diesel is relatively lower than the process of transesterification that produces biodiesel [ 53 ].

Renewable fuel may be used as a partial solution or combination with any percentage of petroleum-based diesels, without altering the engines or vehicle fuel tank design [ 54 ]. The simplest form of hydrocarbon molecules with combination of straight chain and branched paraffin in renewable diesel, is considered to be safe fuel based on complete combustion perspective.

Standard carbon numbers are C12—C18 [ 56 ]. Paraffin, which contains a large amount of aromatic and naphthenic substances, is often present in diesel oil. The EN petrol diesel fuel standard is suitable for different types of diesel engines. This specification has seven different grades and No.

Biodiesel is a mono-alkyl ester produced from the long-chain, carbonic fatty acid. It is formed by transesterification of oil-rich fats or biomass. It is possible to convert triglycerides to esters with more gasoline-like properties [ 59 ].

Triglycerides react with alcohol, such as methanol and ethanol, in the presence of alkaline catalyst, such as potassium hydroxide and at certain temperatures [ 60 ]. It produces methyl or ethyl esters and is a co-product of glycerine.

Renewable diesel is a similar process, except that vegetable oil is processed at high pressure and high temperature in the presence of hydrogen and strong catalyst [ 61 ]. This process can also be carried out with any crude oil. Palm oil, pine oil, potato oil, corn oil is the most common vegetable oil [ 62 ]. However, renewable diesel can be generated from a broader variety of feed stocks than biodiesel.

Two key reasons why this is supported are as follows:. The level of unsaturation of feedstock molecules is not considered as the effects as hydrotreatment result in fully saturated paraffin hydrocarbons that are not sensitive to oxidative instability throughout the biodiesel containment of unsaturated methyl esters [ 63 ]. Thus, the production of Hydrogenated Vegetable Oil does not rely on the free fatty acids of the feedstock [ 64 ].

The fatty acid methy esters are tested based on ASTM standards [ 65 ]. Multiple studies argued that the prices of FAME are very different. This variation in properties, as with the fatty acid profiles, is primarily due to the use of various analytical techniques and varying degrees of performance. All sources of uncertainty are the chemical method used for the production of FAME, the cleaning and washing process used for raw FAME and the storage period prior to the testing [ 67 ].

The oxidation stability of FAME is a key property of biodiesel, but this review has not been taken into account, as the cleaning and storage activities of FAME strongly influence the same [ 68 ].

In addition, some of the biodiesel samples included antioxidant additives which had altered the inherent stability of FAME. There are some other FAME for which standards have been developed, but which also rely mainly on production and handling practises and not on FAME itself [ 69 ]. These include water, sediment, methanol content, ash, metal, acid count, glycerin and cold soak filtering.

The method used to evaluate the biodiesel properties reported in the literature was close to that used for the above fuel [ 70 ].

Initially, without a prior judgement on the validity of the data, all recorded values were recognised. The mean and standard deviations for each FAME are determined from this raw data [ 71 ]. Careful inspections were then carried out, in particular for values which varied significantly from the average. Since the viscosity varies significantly with the temperature, the non-normal temperature values have been omitted when deciding the mean and standard deviations [ 73 ].

However, several authors have recorded energy content values, but the measurements used are very contradictory. For example, lower heating, higher heating value, gross energy content and net energy content were all noted, usually without specific measurements [ 75 ]. Some sources have not suggested the exact metric.

The average chain length was determined by multiplying the mass fraction of the FA portion by the corresponding carbon number, and then adding the entire component [ 76 ]. Similarly, the mean degree of unsaturation was determined and summarised by multiplying the corresponding amount of carbon double bonds by the mass fraction of each FA component [ 77 ].

Biodiesel properties can differ considerably from one feedstock to another [ 78 ]. However, the characteristics of conventional diesel are also useful for a brief comparison of some critical properties of biodiesel fuels as shown in Table 7. Renewable diesel is as clear and bright as water with high heating value.

Low sulphur and metal-free content make it suitable for various applications. The impurity that causes precipitation over the cloud point makes it a clear fuel. The aromatic linearity makes it almost equivalent to the stability of diesel oil [ 80 ]. The renewable diesel is similar to diesel water solubility and the sustainability of the fuel is not the major concern [ 81 ].

Density also remains almost constant at a low cloud point [ 82 ]. As with conventional bio-diesel, some precipitation of paraffins from the renewable diesel may take place if the temperature is below cloud point for a long period.

It is recommended to store all diesel fuels above cloud point [ 83 ]. Due to the influence of high cetane and low density, CI engines are more widely used. The Cetane index also shows a linear increase with the mixing ratio [ 84 ]. Direct blending limitations could not be applied to other fuel properties such as density, viscosity, the concentration of water. In contrast, reductions in density may result in some fuel savings and flexibility in the refinery process [ 85 ].

They are safe for storage and transport as renewable diesel flash points are above diesel. There is no microbial development of renewable diesel [ 86 ]. Green diesel and diesel oil are highly compatible [ 87 ].

Without impacting fuel processing, engines and exhaust emissions, treatment of vegetable oil is a new way of producing high-quality bio-based diesel fuel. Vegetable oils that are chemically hydrolyzed are paraffin hydrocarbon blends that are free from sulphur and fragrance. By changing the process intensity or further catalytic processing, the cold characteristics of HVO may be modified in accordance with local specifications [ 89 ].

The amount of Cetane is very high and the other properties of liquid and biomastic-liquid diesel fuel are very similar to Fischer—Tropsch synthesis gas. Table 8 shows the properties of Hydrogenated Vegetable Oil. Table 8 Hydrogenated Vegetable Oil properties [ 80 ]. As HVOs are hydrocarbons, they comply with conventional diesel fuel requirements EN , with the exception of a low-density value.

The lower heat output of HVO is significantly higher than ethanol. One litre or one gallon of HVO will drive the vehicle almost twice as long as ethanol-based fuel, such as E60, compared to spark ignition engines, where greater efficiency is also considered [ 91 ]. When examining the properties of biodiesel extracted from different feedstocks, it is necessary to take into account the essential requirements laid down by the various organisations of the basic fuel institutions, in particular the European Committee for Standardization CEN [ 92 ].

Mixtures of B15 and below are permitted under the European Standard Conditions for conventional diesel fuel EN and negotiations are on-going to increase the volume of B20 [ 93 ]. Emissions of GreenHouse Gases GHG from biofuels depend not only on the gas produced by the combustion of carbon but also on the combined impact of GHG emissions during the various stages of supply, such as biomass processing, transport to the industrial conversion unit and distribution [ 94 ].

Direct and indirect land use and biomass improvements are well considered in terms of GHG emissions. As bio-energy plants are grown on land previously abandoned for crop cultivation, a direct land-use change takes place [ 96 ]. This applies to grasslands, forests, soil or degraded soil.

As the development of energy crops changes prior to land operation, indirect land-use changes occur [ 97 ]. The land use change results in soil carbon sequestration to increase the mitigation of biofuel. Several studies have shown that, for several decades, converting cropland to grassland for grass cultivation usually raises soil carbon at a rate of 0. In addition to the two main environmental issues referred to above, the production of biofuels will either directly or indirectly affect the supply of water and nutrients [ ].

Biomass feedstock farming requires water and nutrients, regardless of the method of biofuel processing [ ]. The use of sea water or wastewater for bio-mass cultivation may be a potential option instead of freshwater. Seawater is readily available, but its high salinity in a variety of species precludes its application [ ].

Biofuel feedstocks of first and second generation in raw waste water are difficult to produce. However, as described above, with the use of nutrients in waste water and seawater, algae can grow, which reduces the need for freshwater [ ]. Algae cultivation thus provides an optimised system for waste water or water use for the production of biofuels. Engines working with ethanol fuel emit less carbon monoxide than petrol engines. A number of studies have been conducted to reduce net GHG emissions from lignocellulosic ethanol relative to fossil fuels [ ].

The corn stovers had reduced GHG emissions by about 7 and 18 compared to natural gas and coal as a source of heat and energy [ ]. Net emissions of GHGs vary by source of biofuel and are correlated with significant volumes of by-products produced during the processing of biofuels, which involves a Life-Cycle Assessment of the treatment of biofuels from multiple sources to quantify the net emissions of GHGs [ ].

LCA analyses on lignocellulosic ethanol from switchgrass and corn stover in Canada have shown that corn stover are more desirable than switchgrass for net GHG emissions when using Cradle-to-Grave analysis for the processes [ ]. Table 9 represents Life Cycle Assessment of biodiesel [ ]. Biodiesel and petroleum diesel are very similar fuels, but they are not identical.

However, the differences are remarkably small when we consider the radically different procedure for making biodiesel as compared to petroleum diesel. Many additives are available that can modify the properties of biodiesel fuel, and biodiesel can be easily blended with petroleum diesel fuel if desired.

For additional information, please refer to the following Penn State Extension fact sheets and reports:. Agarwal, A. Bijwe, and L. Bhale, P. Deshpande, and S. Bruwer, J. Hugo, L. Fuls, C.

Hawkins, A. Cetinkaya, M. Tekin, and F. Fernando, S. Karra, R. Hernandez, and S. Flitney, R. Graboski, M. Hancsok, J. Bubalik, A. Beck, and J. Knothe, G. Lapuerta, M. Armas, and J. Ryan, T. Dodge, and T. Singh, and S. Zheng, M. Mulenga, G. Reader, M. Wang, D. Ting, and J. Penn State Biomass Energy Center. Let's Stay Connected. By entering your email, you consent to receive communications from Penn State Extension.

View our privacy policy. Thank you for your submission! What's So Different about Biodiesel Fuel? This article compares biodiesel with traditional petroleum diesel fuel, discussing properties, quality, blends ,and enhancement additives. Introduction Biodiesel is a liquid fuel that is created by chemically processing vegetable oil and altering its properties to make it perform more like petroleum diesel fuel.

Many motorists are not aware of the differences between Neste's renewable diesel and traditional biodiesel, even though they should be. They are, however, different products, even though both are made from organic biomasses.

The differences can be found, for example, in their production process, cleanliness, and quality. In the production process, impurities are removed from the raw materials which are then hydrotreated at a high temperature.

The outcome is a colorless and odorless fuel of an even quality that has an identical chemical composition with fossil diesel. It is also often called an "advanced biofuel" or "second-generation biofuel". Traditional, first-generation FAME-type biodiesel, on the other hand, is produced by esterifying vegetable oils or fats. The esterification process restricts the use of poor quality or impure raw materials, such as waste and residues.

The quality of traditional biodiesel varies also in other respects according to the raw materials used. Even though both bio-based fuels help in replacing fossil fuels with renewables and thereby reduce global climate emissions, only renewable diesel can be used in high concentrations and even as a standalone product in all diesel engines.

The use of renewable diesel in high concentrations and as such became recently even easier in Europe thanks to a new EN standard. In the U. From the perspective of chemical composition, conventional fossil diesel and renewable diesel are both hydrocarbons.

Traditional biodiesel is an esther, which may cause problems in some motor engines.