Gasoline

• 1. Introduction

  ›

  Gasoline sits at the center of modern life in a way few substances can match. It is a transparent, yellowish liquid, flammable and faintly sweet-smelling, and yet the world has arranged itself almost entirely around its combustion. Roughly 19 gallons of it can be wrung from a single 42-gallon barrel of crude oil. Worldwide, cars and vans burn through about 7 litres of it for every 100 kilometres driven. And in the United States alone, transportation powered largely by gasoline accounts for 30 percent of the entire country's carbon footprint.

  How did a byproduct of petroleum refining become so central to global civilization? What is actually in the fuel that goes into an engine? And what price, measured in health, environment, and geopolitics, has the world paid to keep it flowing? Those are the questions this documentary sets out to answer.

• 2. Origins and Early Engines

  ›

  Otto engines, developed in Germany during the last quarter of the 19th century, gave the world its first practical internal combustion machines suited to transportation. The fuel that fed them was not gasoline as we know it today. It was a volatile hydrocarbon obtained from coal gas, with a boiling point near 85 degrees Celsius, which made it well matched to the primitive evaporator-style carburettors of the era.

  The invention of a spray nozzle carburettor changed what fuels were usable, opening the door to less volatile liquids derived from crude oil. Engineers then pushed toward higher compression ratios to extract more power, but a stubborn problem blocked progress: at higher compressions, fuel ignited prematurely, causing a destructive hammering inside the engine known as knocking. That single engineering obstacle would drive a century of chemistry.

  In 1891, the Shukhov cracking process became the world's first commercial method to break heavier hydrocarbons in crude oil into lighter fractions. It was a turning point. Cracking allowed refiners to increase the proportion of lighter, more usable products from each barrel of crude, and it laid the technical foundation for the high-volume gasoline industry that followed.

• 3. What the Fuel Actually Contains

  ›

  Commercial gasoline is not a single compound. It is a complex mixture of hydrocarbons, with the bulk of a typical blend made up of molecules carrying between four and twelve carbon atoms per molecule, a range the industry shortens to C4-C12. Within that range sit paraffins, olefins, naphthenes, and aromatics, each contributing differently to the fuel's performance.

  Refineries blend several distinct streams to build finished gasoline. Straight-run gasoline, sometimes called naphtha, is distilled directly from crude and has a low octane rating on its own. Reformate, produced by running naphtha through a catalytic reformer, carries a high octane rating and elevated aromatic content. Alkylate, made from isobutane and olefins, contains no aromatics or olefins at all and was used in aviation fuel during World War II; since the late 1980s it has been sold as a specialty fuel for handheld gardening and forestry tools. Each stream's proportion in the final blend depends on the refinery's equipment, the crude oil it processes, and the octane grade being targeted.

  Oxygenates are also blended in. In the United States, ethanol has largely replaced earlier additives; most retail gasoline now sold there contains about 10 percent ethanol. Brazil mandates 27.5 percent ethanol by composition. In the European Union, the limit under the common gasoline specification is 5 percent, though Finland already sells a blend called 95E10 containing 10 percent ethanol at most stations. The safety data sheet for a 2003 Texan unleaded gasoline listed at least 15 hazardous chemicals, including benzene at up to 5 percent by volume and toluene at up to 35 percent by volume.

• 4. The Octane Wars

  ›

  Octane rating measures a fuel's resistance to premature ignition, and for much of the 20th century, militaries and engineers treated it as a strategic resource. The metric is calculated relative to a reference mixture of 2,2,4-trimethylpentane and n-heptane, and different countries use different conventions, so the same physical fuel can carry several different numerical ratings depending on where it is sold.

  In 1943, the Rolls-Royce Merlin aero engine produced 1,320 horsepower running on 100 RON fuel from a displacement of just 27 litres. By the time of Operation Overlord, both the RAF and the USAAF were flying some operations on 150 RON fuel, a blend called 100/150 avgas made by adding 2.5 percent aniline to 100-octane aviation gasoline. The Rolls-Royce Merlin 66, using that fuel, reached 2,000 horsepower. Some scientists of the era predicted that a nation with a reliable supply of high-octane gasoline would hold the decisive edge in air power.

  For consumer fuels, the geography of octane is uneven. In Finland, Sweden, and Norway, 95 RON is the standard for regular unleaded, with 98 RON available as a premium option. In the United Kingdom, over 95 percent of gasoline sold carries 95 RON, while branded high-performance fuels such as Shell V-Power and BP Ultimate reach 99 RON. In South Africa, the Automobile Association recommends 93-octane for use in Johannesburg, which sits on the Highveld at 1,753 metres above sea level, because lower air pressure at altitude reduces the performance benefit of higher octane.

• 5. The Lead Chapter

  ›

  Tetraethyl lead was widely adopted as a gasoline additive in the 1920s because it solved the knocking problem cheaply and effectively. For decades it worked exactly as intended. Then the evidence against it accumulated.

  Lead compounds proved incompatible with catalytic converters, which began appearing on cars in the 1970s. More pressingly, research linked lead exposure to serious health and cognitive harm. In the United States, the Environmental Protection Agency issued regulations to reduce lead content in stages, originally scheduled to begin in 1973 but delayed by court appeals until 1976. By 1995, leaded fuel made up only 0.6 percent of total U.S. gasoline sales and involved under 2,000 short tons of lead per year. The U.S. Clean Air Act banned the sale of leaded fuel for on-road vehicles from January 1996. European countries began removing lead additives at the end of the 1980s, and by the end of the 1990s leaded gasoline was banned across the entire European Union, with one exception: Avgas 100LL for general aviation.

  In August 2021, the UN Environment Programme announced that leaded gasoline had been eradicated worldwide, with Algeria being the last country to deplete its reserves. UN Secretary-General Antonio Guterres described it as an international success story and stated that ending leaded petrol would prevent more than one million premature deaths each year from heart disease, strokes, and cancer. Greenpeace called the announcement the end of one toxic era. Leaded gasoline continues in aeronautic, auto racing, and some off-road uses, because the required octane ratings for aviation formulations remain difficult to reach without lead additives.

• 6. Health and the Sniffing Crisis

  ›

  Gasoline carries acute hazards beyond the tail-pipe. The National Institute for Occupational Safety and Health has designated gasoline a carcinogen, and benzene, one of its components, can cause leukaemia at concentrations above 40 parts per million. Carbon monoxide produced by combustion binds to haemoglobin in the blood at an affinity 300 times greater than oxygen, causing hypoxia, headache, dizziness, and, in severe cases, death.

  A separate and less-discussed health crisis involves the deliberate inhalation of gasoline vapour. Sniffing gasoline as an intoxicant has become epidemic in some poorer communities and indigenous groups in Australia, Canada, New Zealand, and parts of the Pacific Islands. In 1993, children in the isolated Northern Labrador community of Davis Inlet became the focus of national concern in Canada after many were found to be sniffing gasoline. The Canadian and Newfoundland and Labrador governments intervened repeatedly, sending children for treatment. The community was relocated to the new settlement of Natuashish in 2002, but serious inhalant abuse continued there. Similar problems emerged in Sheshatshiu in 2000 and in Pikangikum First Nation, and the issue made the news again in Canada in 2012.

  In Australia, the problem runs deep across remote Aboriginal communities in the Northern Territory, Western Australia, northern parts of South Australia, and Queensland. In 2005, the Government of Australia and BP Australia began distributing Opal fuel in areas prone to petrol sniffing. Opal is a non-sniffable formulation far less likely to produce intoxication, and it has made a measurable difference in some communities.

• 7. The Environmental Reckoning

  ›

  Burning one litre of gasoline produces about 2.35 kilograms of carbon dioxide. In the United States, transportation is the largest single source of carbon emissions, at 30 percent of the national total. Oil products, including gasoline, were responsible for about 32 percent of emissions worldwide in 2021.

  The costs go beyond climate. Gasoline exhaust contains nitrogen oxides that irritate lung tissue and eyes, aromatic hydrocarbons that cause blood toxicity and neurological harm, and fine particulates linked to respiratory disease. Unburnt gasoline and tank evaporation, when exposed to sunlight in the atmosphere, react to produce photochemical smog. The social costs of gasoline use, covering premature deaths, asthma, higher healthcare costs, reduced crop yields, missed school and work days, and extreme weather linked to climate change, have been estimated at 3.80 dollars per gallon, on top of what consumers pay at the pump.

  Storage also poses environmental risks. Leaks from underground storage tanks are the chief threat, not vehicle spills. Most storage tanks now carry monitoring systems to detect and prevent contamination of soil and groundwater. When gasoline does reach groundwater, people can be exposed through drinking water near spill sites, through skin contact, or simply by breathing fumes while refuelling at a station. The International Energy Agency stated in 2021 that governments must continue regulatory efforts to monitor and reduce the gap between real-world fuel economy and the rated performance figures that are used to set emissions standards.