What petroleum product is gasoline made of


Lexicon> Letter B> Gasoline

Definition: a liquid fuel mainly used for gasoline engines

Alternative term: petrol

More general terms: fossil fuel

More specific terms: motor gasoline, aviation gasoline, regular gasoline, premium gasoline, summer gasoline, winter gasoline, equipment gasoline, white gas, alkylate gasoline

English: petrol, gasoline

Categories: Energy carriers, vehicles, engines and power plants

Author: Dr. Rüdiger Paschotta

How to quote; suggest additional literature

Original creation: 03/12/2010; last change: 08.05.2021

URL: https://www.energie-lexikon.info/benzin.html

petrol is a liquid fuel that is mainly used for the operation of gasoline engines (Motor gasoline), to a lesser extent for various other purposes, e.g. B. as a solvent. The term Petrol is not very precise, as gasoline engines can also be operated with other fuels such as ethanol or natural gas.

Did you know how harmful gasoline is and that you should be very careful when refueling?

Gasoline is essentially a mixture of relatively light hydrocarbons. It evaporates easily even at room temperature, is highly flammable (with a flash point below −20 ° C) and has a relatively strong smell. Petrol fumes are toxic and carcinogenic, partly because of their benzene (= benzene) content, which is now limited to 1% in the EU. In industry, strict safety regulations apply to the handling of liquids containing benzene; At petrol stations, on the other hand, these do not apply, and petrol can easily be splashed and inhaled there, which is extremely hazardous to health.

density0.72 to 0.78 kg / l
calorific value41 MJ / kg = 11.4 kWh / kg,
30.8 MJ / l = 8.5 kWh / l
Calorific value43 MJ / kg = 11.9 kWh / kg,
32.3 MJ / l = 9.0 kWh / l
(105% of the calorific value)
combustionAir requirement (for λ = 1):
8.84 m3 per liter of gasoline.
Combustion products:
CO2: 2.3 kg per liter of petrol
(269 g / kWh in terms of calorific value)
H2O: 1.1 kg per liter of gasoline
(128 g / kWh in terms of calorific value)
Manufacturingadditional emissions of around 10% of those during incineration (when manufactured from conventionally extracted petroleum)

The calorific value of gasoline is approx. 41 MJ / kg, the calorific value 43 MJ / kg; further data can be found in the table on the right. However, these values ​​depend somewhat on the type of gasoline (see below).

Petrol types

Motor gasoline is offered at the petrol stations in different sorts, which can differ in different ways:

  • An important feature is that Octane number (ROZ), which the Anti-knock indicates. Regular gasoline with RON 91 is hardly used anymore, however Premium gasoline (in Switzerland Unleaded 95) with RON 95 and Super Plus (Unleaded 98) with 98 RON. Petrol engines are designed for petrol with a certain knock resistance; If this is not achieved, the engine can be damaged by intense knocking. Few engines can automatically adjust to different octane numbers with the help of a knock sensor. There is a tendency for higher engine outputs and, above all, efficiencies to be possible with a higher octane rating, but only if the engine is designed for this, i.e. H. works with higher compression.
  • Petrol can contain an admixture of ethanol (often bioethanol) - up to 5% in Germany for a long time. The varieties offered since 2011 with the addition “E10” (e.g. “Super E10”) contain 10% bioethanol. The section “Adding Ethanol” below gives more details on this subject.
Also read the article "Save gasoline"!
  • Leaded gasoline contains lead-containing additives (mostly tetraethyl lead) to increase the octane number. Since it damages catalytic converters and leads to additional toxic exhaust emissions, in the EU only unleaded gasoline offered, except for Aviation fuel. Only very old engines lose their service life when they run on unleaded petrol.
  • For two-stroke engines Two-stroke mixture, Gasoline with added lubricating oil.
  • For small devices such as chainsaws and lawn mowers, there is often something special Equipment gasoline used (see below), which is much less harmful to health when inhaling the exhaust gases or petrol fumes. There is also a two-stroke mixture available for two-stroke engines.

The usual types of gasoline are anything but harmless to health. The often considerable content of benzene, which has been recognized as carcinogenic, is particularly problematic. Not only various pollutants that occur as combustion products of gasoline are ecologically questionable, but also so-called evaporative emissions, which occur primarily when fueling gasoline-powered vehicles and sometimes also when parking, especially in the sun. However, there are various technical measures to minimize such evaporative emissions.

Manufacture of gasoline

The production of gasoline involves several steps:

  • Crude oil is extracted in various countries (e.g. in the Middle East and Russia) and transported in tankers to oil refineries, which are usually closer to the consumers.
  • Various products are made from it in the oil refineries, but not the fuels ultimately sold. In addition to fractional distillation, various other process steps (e.g. cracking, isomerization and reforming) are necessary there.
  • Gasoline is in Blending stations blended from refined products. In particular, various additives are used to avoid corrosion, deposits, carburetor icing and the formation of vapor bubbles. This mixture can be slightly different depending on the brand of fuel, but the fuels produced must comply with state-set standards.

During the production of gasoline from conventionally obtained crude oil (crude oil production, transport and refining), emissions that are harmful to the climate are around 10% of the CO2-Emissions that are later created by burning the gasoline. (The majority of these additional emissions arise in the refinery, the second largest in the production of crude oil; the transport of the oil tanker and is less important.) The energy consumption of energy during production is around 18% of the energy content of the fuel. When extracting crude oil using non-conventional methods, however, energy consumption and emissions can be much higher.

Tool petrol - a good solution for your lawnmower and for small appliances such as hedge trimmers.

Equipment gasoline is also a petroleum product, but is obtained differently: not by mixing different distillation fractions, but by chemical synthesis from gases that arise during the distillation of the crude oil. The petrol in the device consists largely of alkanes (= paraffins) and contains practically none of the carcinogenic aromatics such as benzene (= benzene); it is also called Alkylate gasoline or green gasoline designated. Therefore, its use is significantly less hazardous to health. However, its production is considerably more complex and therefore more expensive.

Other synthetic gasoline can be obtained by liquefying coal from coal or from natural gas. In both cases, a significant part of the energy of the primary raw material is lost. In the case of coal liquefaction, the environmental impact is massively higher than in the production of gasoline from crude oil, although the fuel produced tends to be less harmful to the environment in use.

Admixture of ethanol

Gasoline consists largely of petroleum products, but a certain amount of ethanol can also be added - usually so-called bioethanol, i.e. ethanol-alcohol made from plants. This was already practiced during the economic crisis after the First World War; At that time, ethanol obtained from potatoes was used as a so-called Strength spirit. Afterwards, ethanol was barely used for a long time, but in recent years it has been increasingly used again. An admixture of 5% is widespread without the fuel being labeled accordingly. Since 2011, according to the EU biofuel directive, petrol stations have also had to offer types of petrol with the suffix “E10” (e.g. “Super E10”), which contain an increased proportion of 10% bioethanol.

The addition of bioethanol reduces the CO2Emissions?

The first advantage of adding bioethanol is that less crude oil is required, so that dependency on crude oil producers is reduced accordingly. The climate-damaging CO2Emissions a little lower. However, the latter effect is rather insignificant, because on the one hand the ethanol production also causes certain emissions and other additional environmental pollution (e.g. from pesticides, agricultural machinery and slash and burn) and on the other hand the fuel consumption is slightly increased due to the lower calorific value of the ethanol. It is hoped that the proportion of ethanol will result in at least 35% lower CO2Emissions, which makes up only a few percent for the fuel. Despite regulations for the sustainability of ethanol production, there are doubts whether z. B. the additional damage to rainforests can actually be prevented. It is therefore controversial to what extent the addition of ethanol has overall ecological advantages. In addition, there may be competition with the cultivation of food. This can lead to an increase in food prices and thus aggravate hunger in the world. The articles on biomass and biofuels contain more details on this.

The knock resistance of the fuel is increased by the addition of ethanol, or other additives for this purpose (such as tetraethyl lead or the carcinogenic benzene) are required less or not at all. With a high proportion of ethanol (e.g. 85% in E85), the knock resistance is much higher than that required for conventional gasoline engines. This makes it possible to operate engines with a significantly higher compression ratio and correspondingly higher efficiency and higher power. However, these are then no longer suitable for petrol operation.

Another advantage of adding ethanol is that the exhaust gases from vehicles contain less carbon monoxide than when running on pure gasoline.

Can Older Cars Take E10 Fuel? What if they don't?

A technical problem is that E10 is not suitable for many older vehicles because the ethanol contains certain materials such as e.g. B. attack natural rubber, PVC and aluminum in the fuel system and thus cause serious damage (even if you refuel once). Drivers of such vehicles must therefore absolutely fill up with petrol with little or no ethanol. (Retrofitting the vehicle is unlikely to be possible or worthwhile.) You can find out which vehicles are affected from the car manufacturers or from other sources such as DAT [2]. The filling stations are obliged to continue to offer normal premium gasoline. However, this would often require the expensive installation of an additional tank and possibly additional fuel pumps, which is why often only the “Super plus” variety is offered with a lower proportion of ethanol. So many drivers will be forced to fill up with the more expensive “Super plus”, even though the higher knock resistance is actually not needed.

Another technical problem can arise if the gasoline gets very cold. The proportion of ethanol tends to absorb water, which is then separated out again at low temperatures. If such a pure water content is sucked in in sufficient quantity by the engine, the engine can shut down. Although this is a very rare case in road traffic (because it hardly ever gets cold enough, at least in Central Europe), it should not normally be a serious problem. When used as aviation fuel in a propeller aircraft, however, a failure of the engine is very problematic in terms of safety.

Since the calorific value of the gasoline decreases by almost 2% due to the ethanol admixture, an additional fuel consumption of approx. 3.5% is to be expected with Super E10 compared to pure super gasoline. Since petrol that is not specially labeled can already contain 5% ethanol, the difference is likely to be just under 2%. This means that if the price difference is close to 2%, which is usually the case, using Super E10 is about equally cheap financially.

Is the bioethanol admixture really ecologically motivated, or is it a gift for the agricultural lobby?

There is a suspicion that the interests of agriculture played a more important role in the energy policy decision on the mandatory E10 offer than the minor climate protection effect, which is offset by ecological disadvantages anyway. The German government also viewed the addition of ethanol as a substitute for a correspondingly greater reduction in consumption in cars, which was supported by the car industry. In the event that the obligation to add ethanol is abandoned or reduced, it would be necessary for the consumption of new vehicles to be reduced more in order to achieve the climate targets that have been set.

A certain political pressure in the direction of reducing ethanol blends arises in Europe from the fact that oil refineries generate increasing excess gasoline, which threatens their economic viability. This is not least a consequence of the preferential tax treatment for diesel fuel.

Prices and Taxes

Like most other fuels, petrol is subject to mineral oil tax in most countries. B. heating oil. Often the tax component of the gasoline price is well over 50%. The proceeds from the mineral oil tax are generally used to a certain extent for road construction and similar purposes, but partly also for general state financing.

Comparison with diesel fuel

The article on diesel fuel contains an in-depth comparison of diesel and gasoline.

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See also: fuel, hydrocarbons, benzene, saving fuel, carburetor, fuel injection, aviation fuel, gasoline engine, diesel fuel, bioethanol, knock resistance, petroleum refining, tank tourism, coal liquefaction, mineral oil tax, evaporative emissions
as well as other items in the categories of energy carriers, vehicles, engines and power plants