Additives

Lead

Gasoline, when used in high compression internal combustion engines, has a tendency to autoignite (detonation) causing a damaging "engine knocking" (also called "pinging" or "pinking") noise. Early research into this effect was led by A.H. Gibson and Harry Ricardo in England and Thomas Midgley and Thomas Boyd in the United States. The discovery that lead additives modified this behavior led to the widespread adoption of their use in the 1920s and therefore more powerful higher compression engines. The most popular additive was tetra-ethyl lead. Its use continued for decades despite the deaths of several members of the original research teams from lead poisoning. Marketing materials purposely avoided mentioning lead explicitly, and instead "Ethyl" was used. However, with the discovery of the extent of environmental and health damage caused by the lead, and the incompatibility of lead with catalytic converters found on virtually all newly sold US automobiles since 1975, this practice began to wane (encouraged by many governments introducing differential tax rates) in the 1980s. Most countries are phasing out leaded fuel; different additives have replaced the lead compounds. The most popular additives include aromatic hydrocarbons, ethers and alcohol(usually ethanol or methanol). In the US, where lead had been blended with gasoline (primarily to boost octane levels) since the early 1920s, standards to phase out leaded gasoline were first implemented in 1973 - due in great part to studies conducted by Philip J. Landrigan. In 1995, leaded fuel accounted for only 0.6% of total gasoline sales and less than 2000 short tons (1814 t) of lead per year. From 1 January 1996, theClean Air Act banned the sale of leaded fuel for use in on-road vehicles. Possession and use of leaded gasoline in a regular on-road vehicle now carries a maximum $10,000 fine in the US. However, fuel containing lead may continue to be sold for off-road uses, including aircraft, racing cars, farm equipment, and marine engines. Similar bans in other countries have resulted in lowering levels of lead in people'sbloodstreams.

A side effect of the lead additives was protection of the valve seats from erosion. Many classic cars' engines have needed modification to use lead-free fuels since leaded fuels became unavailable. However, "Lead substitute" products are also produced and can sometimes be found at auto parts stores. These were scientifically tested and some were approved by the Federation of British Historic Vehicle Clubs at the UK's Motor Industry Research Association (MIRA) in 1999.

In some parts of South America, Asia, Eastern Europe and the Middle East, leaded gasoline is still in use. Leaded gasoline was phased out in sub-Saharan Africa effective 1 January 2006. A growing number of countries have drawn up plans to ban leaded gasoline in the near future.

MMT

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used for many years in Canada and recently in Australia to boost octane. It also helps old cars designed for leaded fuel run on unleaded fuel without need for additives to prevent valve problems.

US Federal sources state that MMT is suspected to be a powerful neurotoxin and respiratory toxin, and a large Canadian study concluded that MMT impairs the effectiveness of automobile emission controls and increases pollution from motor vehicles.

In 1977 use of MMT was banned in the US by the Clean Air Act until the Ethyl Corporation could prove that the additive would not lead to failure of new car emission-control systems. As a result of this ruling, the Ethyl Corporation began a legal battle with the EPA, presenting evidence that MMT was harmless to automobile emissions-control systems. In 1995 the US Court of Appeals ruled that the EPA had exceeded its authority, and MMT became a legal fuel additive in the US. MMT is nowadays manufactured by the Afton Chemical Corporation division of Newmarket Corporation.

Ethanol

United States

In the United States, ethanol is sometimes added to gasoline but sold without an indication that it is a component.

In several states, ethanol is added by law to a minimum level which is currently 5.9%. Most fuel pumps display a sticker stating that the fuel may contain up to 10% ethanol, an intentional disparity which allows the minimum level to be raised over time without requiring modification of the literature/labelling. Until late 2010, fuels retailers were only authorized to sell fuel containing up to 10 percent ethanol (E10), and most vehicle warranties (except for flexible fuel vehicles) authorize fuels that contain no more than 10 percent ethanol.

European Union

In the EU, 5% ethanol can be added within the common gasoline spec (EN 228). Discussions are ongoing to allow 10% blending of ethanol (available in French gas stations). Most gasoline sold in Sweden has 5-15% ethanol added, also there is sold petrol blended ethanol, 85% ethanol 15% petrol.

Brazil

In Brazil, the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP) requires that gasoline for automobile use has 25% of ethanol added to its composition, as dictated by the Ministry of Agriculture.

Australia

Legislation limits ethanol use to 10 per cent of gasoline in Australia. It is commonly called E10 by major brands and is less expensive than regular unleaded petrol. It is also required for retailers to label fuels containing ethanol on the dispenser.

Dye

In the United States the most commonly used aircraft gasoline, avgas, or aviation gas, is known as 100LL (100 octane, low lead) and is dyed blue. Red dye has been used for identifying untaxed (non-highway use) agricultural diesel.

The UK uses red dye to differentiate between regular diesel fuel, (often referred to as DERV from Diesel-Engined Road Vehicle), which is undyed, and diesel intended for agricultural and construction vehicles like excavators and bulldozers. Red diesel is still occasionally used on HGVs which use a separate engine to power a loader crane. This is a declining practice however, as many loader cranes are powered directly by the tractor unit.

In Australia, petrol tends to be dyed a light shade of purple.

In India, where leaded fuels are mainstream, petrol is dyed red.

In South Africa un-leaded fuel is dyed green and lead-replacement fuel is dyed red.

Oxygenate blending

Oxygenate blending adds oxygen to the fuel in oxygen-bearing compounds such as MTBE, ETBE and ethanol, and so reduces the amount of carbon monoxide and unburned fuel in the exhaust gas, thus reducing smog. In many areas throughout the US oxygenate blending is mandated by EPA regulations to reduce smog and other airborne pollutants. For example, in Southern California, fuel must contain 2% oxygen by weight, resulting in a mixture of 5.6% ethanol in gasoline. The resulting fuel is often known as reformulated gasoline (RFG) or oxygenated gasoline, or in the case of California, California reformulated gasoline. The federal requirement that RFG contain oxygen was dropped 6 May 2006 because the industry had developed VOC-controlled RFG that did not need additional oxygen.

MTBE use is being phased out in some states due to issues with contamination of ground water. In some places, such as California, it is already banned. Ethanol and to a lesser extent the ethanol derived ETBE are common replacements. Since most ethanol is derived from biomatter such as corn, sugar cane or grain, it is referred to as bio-ethanol. A common ethanol-gasoline mix of 10% ethanol mixed with gasoline is called gasohol or E10, and an ethanol-gasoline mix of 85% ethanol mixed with gasoline is called E85. The most extensive use of ethanol takes place in Brazil, where the ethanol is derived from sugarcane. In 2004, over 3.4 billion US gallons (2.8 billion imp gal/13 million m³) of ethanol was produced in the United States for fuel use, mostly from corn, and E85 is slowly becoming available in much of the United States, though many of the relatively few stations vending E85 are not open to the general public. The use of bioethanol, either directly or indirectly by conversion of such ethanol to bio-ETBE, is encouraged by the European Union Directive on the Promotion of the use of biofuels and other renewable fuels for transport. However since producing bio-ethanol from fermented sugars and starches involves distillation, ordinary people in much of Europe cannot legally ferment and distill their own bio-ethanol at present (unlike in the US where getting a BATF distillation permit has been easy since the 1973 oil crisis.)

Other additives

Gasoline, as delivered at the pump, also contains additives to reduce internal engine carbon buildups, improve combustion, and to allow easier starting in cold climates. The highest levels of detergent can be found in Top Tier Detergent Gasolines. The gasolines exceed the EPA minimum requirement for detergent content. The specification for Top Tier Detergent Gasolines was developed by four automakers GM, Honda, Toyota and BMW. According to the bulletin the minimal EPA requirement is not sufficient to keep engines clean.

Health concerns

Uncontrolled burning of gasoline produces large quantities of soot.

Many of the non-aliphatic hydrocarbons naturally present in gasoline (especially aromatic ones like benzene), as well as many anti-knocking additives, arecarcinogenic. Because of this, any large-scale or ongoing leaks of gasoline pose a threat to the public's health and the environment, should the gasoline reach a public supply of drinking water. The chief risks of such leaks come not from vehicles, but from gasoline delivery truck accidents and leaks from storage tanks. Because of this risk, most (underground) storage tanks now have extensive measures in place to detect and prevent any such leaks, such as sacrificial anodes. Gasoline is rather volatile (meaning it readily evaporates), requiring that storage tanks on land and in vehicles be properly sealed. The high volatility also means that it will easily ignite in hot weather conditions, unlike diesel for example. Appropriate venting is needed to ensure the level of pressure is similar on the inside and outside. Gasoline also reacts dangerously with certain common chemicals.

Gasoline is also one of the sources of pollutant gases. Even gasoline which does not contain lead or sulfur compounds produces carbon dioxide, nitrogen oxides, andcarbon monoxide in the exhaust of the engine which is running on it. Furthermore, unburnt gasoline and evaporation from the tank, when in the atmosphere, react insunlight to produce photochemical smog. Addition of ethanol increases the volatility of gasoline.

Through misuse as an inhalant, gasoline also contributes to damage to health. Concentrations of gasoline as low as 0.25 ppm (0.000 025%) can be smelled by most people. Petrol sniffing is a common way of obtaining a high for many people and has become epidemic in some poorer communities and indigenous groups in America, Australia, Canada, New Zealand and some Pacific Islands. In response, Opal fuel has been developed by the BP Kwinana Refinery in Australia, and contains only 5% aromatics (unlike the usual 25%) which inhibits the effects of inhalation.

Like other alkanes, gasoline burns in a limited range of its vapor phase and, coupled with its volatility, this makes leaks highly dangerous when sources of ignition are present. Gasoline has a lower explosion limit of 1.4% by volume and an upper explosion limit of 7.6%. If the concentration is below 1.4% the air-gasoline mixture is too lean and will not ignite. if the concentration is above 7.6% the mixture is too rich and also will not ignite. However, gasoline vapor rapidly mixes and spreads with air making unconstrained gasoline quickly flammable. Many accidents involve gasoline being used in an attempt to light bonfires; rather than helping the material on the bonfire to burn, some of the gasoline vaporises quickly after being poured and mixes with the surrounding air, so when the fire is lit a moment later the vapor surrounding the bonfire instantly ignites in a large fireball, engulfing the unwary user. The vapor is also heavier than air and tends to collect in garage inspection pits.

Environmental concerns

One US gallon of gasoline, when used as a fuel, produces about 19.4 pounds of carbon dioxide (converts to 2.33 kg/litre), a greenhouse gas.

Usage and pricing

UK petrol prices

The US accounts for about 44% of the world’s gasoline consumption. In 2003 The US consumed 476.474 gigalitres (1.25871×10¹¹ US gal; 1.04810×10¹¹ imp gal),which equates to 1.3 gigalitres of gasoline each day (about 360 million US or 300 million imperial gallons). The US used about 510 billion litres (138 billion US gal/115 billion imp gal) of gasoline in 2006, of which 5.6% was mid-grade and 9.5% was premium grade.

Western countries have among the highest usage rates per person.

Based on externalities, some countries, e.g. in Europe and Japan, impose heavy fuel taxes on fuels such as gasoline.

United States

Because a greater proportion of the price of gasoline in the United States is due to the cost of oil, rather than taxes, the price of the retail product is subject to greater fluctuations (vs. outside the US) when calculated as a percentage of cost-per-unit, but is less variable in absolute terms. From 1998 to 2004 the price of gasoline was between $1 to $2 USD per U.S. gallon. After 2004, the price increased until the average gas price reached a high of $4.11 per U.S. gallon in mid-2008, but has receded to approximately $2.60 per U.S. gallon as of September 2009. Recently, the U.S. has experienced an upswing in gas prices of 13.51% from Jan 31st to March 7, 2011.

Unlike most consumer goods, the prices of which are listed before tax, in the United States, gasoline prices are posted with taxes included. Taxes are added by federal, state and local governments. As of 2009, the federal tax is 18.4¢ per gallon for gasoline and 24.4¢ per gallon for diesel (excluding Red diesel). Among states, the highest gasoline tax rates, including the federal taxes as of 2005, are New York (62.9¢/gal), Hawaii (60.1¢/gal), & California (60¢/gal). However, many states' taxes are a percentage and thus vary in amount depending on the cost of the gasoline.

About 9 percent of all gasoline sold in the US in May 2009 was premium gas, according to the Energy Information Administration. Consumer Reports magazine says “If your car can run on regular, run it on regular.” The Associated Press said that premium gas—which is a higher octane and costs several cents a gallon more than regular unleaded—should be used only if the manufacturer says it is “required.” 

Stability

Good quality gasoline should be stable almost indefinitely if stored properly. Such storage should be in an airtight container, to prevent oxidation or water vapors mixing, and at a stable cool temperature, to reduce the chance of the container leaking. When gasoline is not stored correctly and is left for a period of time, gums and varnishes may build up and precipitate in the gasoline, causing "stale fuel". This may cause gums to build up in the fuel tank, lines, and carburetor or fuel injection components making it harder to start the engine. However upon the resumption of regular vehicle usage, the buildups should eventually be cleaned up by the flow of fresh petrol. A fuel stabilizer may be used to extend the life of the fuel that is not or cannot be stored properly. Fuel stabilizer is commonly used for small engines such as lawnmower and tractor engines to promote quicker and more reliable starting. Users have been advised to keep gasoline containers and tanks more than half full and properly capped to reduce air exposure, to avoid storage at high temperatures, to run an engine for ten minutes to circulate the stabilizer through all components prior to storage, and to run the engine at intervals to purge stale fuel from the carburetor.

Gummy, sticky resin deposits result from oxidative degradation of gasoline. This degradation can be prevented through the use of antioxidants such as phenylenediamines, alkylenediamines (diethylenetriamine,triethylenetetramine, etc.), and alkylamines (diethylamine, tributylamine, ethylamine). Other useful additives include gum inhibitors such as N-substituted alkylaminophenols and colour stabilizers such as N-(2-aminoethyl)piperazine, N,N-diethylhydroxylamine, and triethylenetetramine.

Improvements in refinery techniques have generally reduced the reliance on the catalytically or thermally cracked stocks most susceptible to oxidation. Gasoline containing acidic contaminants such asnaphthenic acids can be addressed with additives including strongly basic organo-amines such as N,N-diethylhydroxylamine, preventing metal corrosion and breakdown of other antioxidant additives due to acidity. Hydrocarbons with a bromine number of 10 or above can be protected with the combination of unhindered or partially hindered phenols and oil soluble strong amine bases such as monoethanolamine, N-(2-aminoethyl)piperazine, cyclohexylamine, 1,3-cyclohexane-bis(methylamine), 2,5-dimethylaniline, 2,6-dimethylaniline, diethylenetriamine and triethylenetetramine.

"Stale" gasoline can be detected by a colorimetric enzymatic test for organic peroxides produced by oxidation of the gasoline.

Other fuels

• Biofuels are anything made with natural or organic waste EX; wheat, corn
  • Biodiesel, for diesel engines.
  • Refined vegetable oil
  • Fischer-Tropsch diesel from biomass
  • Biobutanol, for gasoline engines.
  • Bioethanol.
  • Biogasoline.
• Compressed air
• Hydrogen fuel
• Electricity
• Fossil fuels:
  • CNG (Compressed Natural Gas)
  • Petrodiesel