The elimination of harmful exhaust emissions from cars and trucks has been a cornerstone of US environmental policy. Air pollution in the urban environment have been reduced by millions of tons thanks to EPA rules on mobile sources. Octane has been the subject of several EPA gasoline restrictions. Octane is a gasoline ingredient that is required for modern engines to work properly. Octane has been produced in a variety of ways over the years, including renewable and petroleum-based sources. Lead, methyl tertiary butyl ether (MTBE), benzene, toluene, ethyl-benzene, and xylene (BTEX), as well as ethanol, are among them (a biofuel). Lead and petroleum-based octane suppliers have been eliminated from the fuel supply or reduced as negative health and environmental effects have been revealed. The BTEX complex (a petroleum refining product generally referred to as gasoline aromatics) and ethanol are the two principal sources of octane used in the United States today.
The ability of a fuel to avoid knock is measured by its octane rating. Knock happens when fuel is ignited early in the engine’s cylinder, reducing efficiency and potentially damaging the engine. Knock is a term that most current drivers are unfamiliar with. This is due to the presence of an oxygenate in the fuel, which reduces knock by supplying oxygen to the fuel. Octane is the popular name for this oxygenate.
Most retail gas stations provide three octane grades: 87 (normal), 89 (mid-grade), and 91-93 (high-grade) (premium). The octane number indicates how resistant the fuel mixture is to knocking. Higher compression ratios, turbocharging, and downsizing/downspeeding are all possible with higher octane fuels, resulting in improved engine efficiency and performance. High-octane gasoline is now marketed as “premium,” although automakers have expressed interest in boosting the minimum octane pool in the United States to allow for smaller, more efficient engines. This would improve vehicle efficiency while also lowering greenhouse gas emissions by reducing fuel consumption.
Lead
Automobile makers were looking for a chemical that would lessen engine knock in the early twentieth century. In 1921, General Motors engineers discovered that tetraethyl lead (commonly known as lead) added octane to gasoline, avoiding engine knock. While aromatic hydrocarbons (such as benzene) and alcohols (such as ethanol) were also known to provide octane at the time, lead was favored due to its lower cost of manufacturing. Until the mid-1970s, when the US Environmental Protection Agency (EPA) began phasing it out due to documented negative health effects, leaded gasoline was the most common fuel type in the United States.
Health concerns about lead in gasoline were highlighted early on in its use as a fuel additive. In 1924, 15 refinery workers died of probable lead poisoning in New Jersey and Ohio. As a result, the Surgeon General put a temporary halt to the production of leaded gasoline and formed a team to look into the potential effects of lead in gasoline. While the panel found no evidence of lead poisoning over a short period of time, it warned that prolonged lead exposure could cause “chronic degenerative disorders of a less evident type.”
Despite these concerns, the Surgeon General established a voluntary lead content threshold, which the refining sector has met successfully for decades. The fatal health effects of low-level lead exposure were not discovered until the 1960s, after intensive health research. Low-level, ambient lead exposures are especially harmful to children’s developing bodies. Anemia, behavioral issues, low IQ, reading and learning impairments, and nerve damage are among health effects of lead exposure in children. Lead poisoning is linked to hypertension and cardiovascular disease in adults. The overall amount of lead used in gasoline was over 200,000 tons per year prior to the lead phase-out.
In 1970, Congress passed the Clean Air Act, which paved the way for the creation of the Environmental Protection Agency and, eventually, the removal of lead from gasoline. According to the EPA, 68 million children were exposed to dangerous levels of lead from leaded gasoline alone between 1927 and 1987. Between 1970 and 1987, the phase-out of lead in gasoline lowered the number of children with dangerous levels of lead in their blood by 2 million each year.
The Clean Air Act is passed by Congress in 1970. The Environmental Protection Agency (EPA) is established and granted the ability to regulate substances that damage human health.
1973: The EPA mandates a gradual reduction in lead levels in all gasoline grades.
In order to be compatible with 1975 make and model year automobiles, the EPA requires that at least one grade of unleaded gasoline be available. The catalytic converters employed in these new vehicles to regulate exhaust emissions are damaged by lead. Vehicles with catalytic converters are still on the road today.
The EPA bans the use of leaded gasoline in on-road automobiles in 1996. (leaded gasoline was down to 0.6 percent of 1996 gasoline sales). Some aircraft fuels still contain lead.
Lead is no longer present in gasoline in most parts of the world, thanks to concerted efforts. Following the phase-out of lead in the United States, the oil refining industry decided to build more refining capacity to make octane from other petroleum products rather than renewable sources like ethanol.
Methyl Tertiary Butyl Ether (MTBE)
The Clean Air Act Amendments of 1990 (CAAA) were the next major fuel restriction. CAAA mandates the use of reformulated gasoline in places that do not meet ground-level ozone requirements, among other things (RFG). RFG has a higher oxygenate concentration, which aids in full combustion. As a result, during combustion, RFG reduces the generation of ozone precursors and other air toxics.
Because of its ease of shipping and mixing, a petroleum derivative, methyl tertiary butyl ether (MTBE), was utilized in 87 percent of RFG by the late 1990s. Ethanol was a more common component of RFG in the Midwest. MTBE was taken out of the gasoline pool despite its success in lowering ozone precursors owing to worries about its solubility in water, which resulted in the poisoning of water supplies in several states. According to the EPA, MTBE was not utilized in large quantities in the United States as of 2005. Reformulated gasoline accounts for 30% of all gasoline sold in the United States. The extra octane required by RFG is provided by ethanol.
1998: The Environmental Protection Agency (EPA) convenes a Blue Ribbon Panel, which concludes that MTBE poses a threat to groundwater resources. The United States Geological Survey (USGS) discovered MTBE in 20% of groundwater supplies in RFG zones at the time.
The EPA announces the phase-out of MTBE in order to preserve drinking water in the year 2000. At the same time, the Environmental Protection Agency (EPA) and the United States Department of Agriculture (USDA) advocate for a greater usage of ethanol to protect air quality.
From 2000 to 2005, seventeen states outlawed or severely restricted the use of MTBE in gasoline pools.
The BTEX Complex
A hydrocarbon combination of benzene, toluene, xylene, and ethyl-benzene makes up the BTEX complex. These compounds, often known as gasoline aromatics, are processed from low-octane petroleum products to create a high-octane gasoline additive. While some BTEX is naturally present in gasoline, it is also added to finished fuel to increase its octane rating. The overall amount of BTEX (aromatics) in finished gasoline is determined by the octane value and other fuel qualities needed.
The increase in BTEX in gasoline was a result of the phase-out of lead. When it came to replacing lead as the principal source of octane in gasoline, refiners had two options: BTEX or ethanol. To replace lead with BTEX, a high-octane petroleum refining product, the refining sector invested in more refining capacity. By 1990, BTEX had risen from 22% to almost a third of the gasoline pool as a result of its replacement for lead. The BTEX volume percentage in premium gasoline grades reached as high as 50%. The EPA has lowered the volume of aromatics in normal gasoline to between 25 and 28 percent of the pool through reformulated gasoline and other efforts, while some health professionals dispute the safety of even these levels.
There were early concerns about the BTEX complex after the lead phase-out. Senator Tom Daschle stated his alarm about gasoline aromatics in 1987, saying, “In the gasoline industry, a revolutionary change is taking place that poses a severe threat to the environment and human health: rising concentrations of benzene and other aromatics.”
Even very low-level exposure to the BTEX complex from gasoline additives and other petroleum products, according to current health studies, may cause detrimental developmental, reproductive, and immunological reactions, as well as cardio-pulmonary impacts. Ultra-fine particles (UFP) and polycyclic aromatic hydrocarbons (PAHs) are generated when the BTEX complex in gasoline is incompletely burned, and they have their own negative health effects even at low levels. UFP and PAHs are mutagenic and carcinogenic. Both UFP and PAHs have been related to developmental and neurological problems, as well as cancer and cardio-pulmonary consequences. Because benzene is so harmful, it has received a lot of attention in the gasoline industry. At the same time, partial replacement of benzene with other aromatic chemicals (xylene, ethyl-benzene, toluene) might not be enough to reduce BTEX exposure.
1990: The Clean Air Act Amendments are passed by Congress, requiring, among other things, that benzene levels in locations that do not meet ground-level ozone criteria be reduced. S.1630, the Clean Octane Amendment, was included in the CAAA and grants the EPA the ability to employ “to replace the hazardous aromatics that are now used to raise octane in gasoline with non-toxic additives.”
2007: The Environmental Protection Agency (EPA) modifies the Control of Hazardous Air Pollutants from Mobile Sources (MSAT2), lowering the overall concentration of benzene in gasoline to 0.62 percent, down from 1.3 percent on average. Toluene and xylene, for example, are not capped aromatics.
Ethanol
Plant-based alcohol fuels, such as ethanol, piqued the curiosity of early automakers. The first Model T to run on ethanol was designed by Henry Ford. However, gasoline was a more cheaper fuel at the time. Standard Oil was also “hesitant… to promote the development and distribution of a competing fuel produced by a business unrelated to petroleum.” Since then, the petroleum industry has dominated the fuels market.
During the 1973 oil embargo, ordinary unleaded gasoline prices rose by 57%, and there were regular gasoline shortages. These events generated fresh interest in fuel efficiency, electric vehicles, and renewable fuels like ethanol, which were considered as methods to fulfill the new restrictions and minimize petroleum consumption. In the United States, the bulk of ethanol is now combined with gasoline to make E10 (10 percent ethanol, 90 percent gasoline). E10 is found in almost 95% of gasoline sold in the United States.
Ethanol is a great octane supplier, with neat (pure) ethanol having an octane rating of over 100, in addition to having lower lifecycle greenhouse gas emissions than conventional gasoline. Refineries currently produce’sub-octane gas,’ which has a lower octane value than what is required. The cheapest octane source, ethanol, is then utilized to raise the gasoline’s octane rating up to the indicated octane value on the gas pump. For example, to meet the minimum octane requirement of 87 for retail gasoline, 84 octane gasoline is commonly blended with 10% ethanol.
Increasing the octane content of gasoline currently has two options: increasing the volume of gasoline aromatics or increasing the volume of ethanol.
Ethanol & Health Concerns
While ethanol has a higher volatility than gasoline, which means it vaporizes faster, it is a more environmentally friendly option to petroleum-based octane boosters. Furthermore, when compared to the health impacts of BTEX and its combustion products, such as ultrafine particles (UFPs) and polycyclic aromatic hydrocarbons, ethanol has a low toxicity (PAHs). A 6.6 percent reduction in cancer risk from tailpipe emissions would result from a small increase in ethanol concentration in fuel from 10% to 15%.
Increased ethanol concentration in gasoline increases nitrous oxide (NOX) emissions, an ozone precursor, according to inconsistent studies. Several studies have found no link between ethanol blending and NOX emissions, or that NOX emissions decrease as ethanol volumes increase. Other research suggests that when utilizing ethanol blends, older cars generate greater NOX. However, a study of 2012 make and model year automobiles found no difference in NOX emissions between E10, E15, and E20 blends, implying that NOX emissions are influenced by both engine design and engine age. In contemporary engine pollution control systems, the effect of ethanol on NOX and carbon monoxide (CO) emissions is modest.
1975: The Energy Policy and Conservation Act (EPAct) is passed by Congress, setting CAFE (Corporate Average Fuel Economy) rules for vehicles and trucks.
1988: The Alternative Motor Fuels Act introduces alternative fuel vehicle incentives under CAFE.
1992: The Energy Policy Act of 1992 defines alternative fuels and provides federal programs to promote alternative fuel use and development.
2005: The Energy Policy Act of 2005 is passed by Congress, establishing the Renewable Fuel Standard (RFS). The Renewable Fuel Standard (RFS) establishes a minimum volume of renewable biofuels that must be blended into the transportation fuel supply.
2007: The Energy Independence and Security Act (EISA) is passed by Congress, raising the volume of renewable fuels mandated under the RFS from 12 billion gallons to 36 billion gallons by 2022.
2013: The EPA proposes decreasing the volume of renewable fuels under the RFS, citing a shortage of renewable fuels infrastructure.
Renewable fuel levels for 20142016 are decided by the administration in 2015. The final renewable fuel quantities for 2016 are 18.11 billion gallons, up around 1 billion gallons from the 2013 request and accounting for little over 10% of total fuel supply. Renewable fuels, cellulosic biofuels, advanced biofuels, and biomass-based diesel are all included.
Conclusions
For more than a century, lead and other petroleum chemicals have contributed octane to gasoline, but new health and environmental concerns have prompted regulators to reexamine their extensive usage. Increasing the octane value of gasoline, which would enable more fuel-efficient engines, is a possible path for the United States as it seeks to lower the transportation sector’s greenhouse gas intensity. However, the health and environmental effects of the octane sources used must also be considered. Splash blending, which involves adding ethanol to finished gasoline, raises octane ratings while minimizing hazardous octane sources.
A countrywide transition to an optimum mid-level ethanol mix, such as E25 (25 percent ethanol, 75 percent gasoline) or E40 (40 percent ethanol), would reduce consumer fuel costs and standardize the supply. The Department of Energy understands that increasing the ethanol percentage of gasoline could help boost the octane rating of the fuel supply. A mid-level ethanol blend would allow for the development of very fuel-efficient engines, reducing petroleum usage, greenhouse gas emissions, and helping to satisfy increasing fuel efficiency criteria. Currently, the Department of Energy and the Environmental Protection Agency have allowed the use of E15 in vehicles with a make and model year of 2001 or later, which account for approximately 80% of all vehicles on the road today.
Clean octane sources are being investigated by automakers as a solution to meet efficiency and greenhouse gas restrictions. In the short term, this is where the greatest benefit to health, the environment, and vehicle efficiency may be obtained.
Why was lead added to gasoline, and how did it get there?
Beginning in 1922, tetraethyl lead was added to gasoline to improve engine performance. Humans, on the other hand, are poisoned by lead. Exposure to leaded gasoline can cause serious neurological damage, which was known for the entire time it was in use.
Nonetheless, for decades, leaded gasoline was the standard in the United States. According to a BBC News report, firms with a stake in ongoing lead use, such as General Motors, funded research to create the misleading impression that leaded gasoline was safe. Competition with leaded gasoline was also one of the reasons why E10 (a mixture of 10% ethanol and 90% gasoline) failed to catch on in the 1930s, only to reappear decades later.
Is there still lead in gasoline?
Leaded gasoline for automobiles and trucks has been phased out globally, but it is still used in aviation, motor sports, and other off-road applications.
What effect does lead additive have on gas?
While lead is added to gasoline to increase the octane number, allowing for higher compression and consequently more efficient engines, it also has additional affects on engine function. The combustion of lead additives produces lead salts, which are deposited on the combustion chamber walls.
When did it become illegal to add lead in gasoline?
When health concerns about lead became apparent in the 1970s, unleaded gasoline was introduced. Leaded gasoline for use in on-road cars was totally phased out in the United States on January 1, 1996. Leaded gasoline is no longer used in most other countries’ cars. Gasoline is now commonly sold in three grades at retail stores.
When was the first time lead was used in gasoline?
Lead gasoline was widely used throughout the mid-twentieth century. It wasn’t: lead is toxic, and burning it had disastrous results. But how did it end up in gasoline to begin with?
The explanation may be traced back to this day in 1921, when a GM engineer called Thomas Midgley Jr. informed his boss Charles Kettering that he’d discovered a new additive that helped to minimize the friction between two metal surfaces “Knocking” is a term used to describe the sound of a car engine. The ingredient in question is tetraethyl lead, sometimes known as TEL or lead tetraethyl, a very poisonous chemical discovered in 1854. His revelation continues to have a far-reaching impact on those who aren’t car owners.
According to James Lincoln Kitman of The Nation in 2000, Kettering had designed the self-starter a decade ago, and the knocking was an issue he couldn’t wait to address. Because of the loud noise, cars became less efficient and more intimidating to buyers. However, there were other anti-knock compounds that were successful. Midgley himself claimed that in his pursuit for an antiknock, he tried any material he could discover, according to Kitman “From melted butter and camphor to ethyl acetate and aluminum chloride,” says the author. Ethanol was by far the most appealing option.
However, ethanol was not an option for GM, according to Kitman. It was impossible to patent, and GM had no control over its manufacture. He wrote that oil companies like Du Pont “hated it,” seeing it as a threat to their control of the internal combustion engine.
TEL, he said, performed the same technical function as ethanol: it reduced knock by increasing the fuel’s combustibility, or “octane.” However, unlike ethanol, it could not be utilized as a gasoline substitute, as it had been in some early autos. The disadvantage was that it was a recognized poison, described by a Du Pont executive in 1922 as “a colorless liquid of sweetish odor, exceedingly toxic if absorbed via the skin, resulting in lead poisoning very instantly.” That statement is significant, according to Kitman: subsequently, major players would deny knowing TEL was so harmful.
The task committee looked at the hazards that drivers, car attendants, and gas station owners face on a daily basis and found that they were negligible. Lead traces were discovered in dusty parts of garages by the researchers. Furthermore, all of the drivers who were examined had trace quantities of lead in their blood. However, the scientists stated that a low quantity of lead might be tolerated.
Exposure levels may climb with time, according to the report. “But, of course, that would be a problem for a future generation,” she writes. Those early measures established a precedent that was difficult to reverse: it wasn’t until the mid-1970s that a growing body of data concerning the risks of leaded gasoline prompted the EPA to launch a years-long legal battle with gasoline manufacturers over its phase-out.
In the United States and other nations where leaded gasoline wasor still isused, the effects of so much lead being burned and forced into the air are still being felt.
“Children are the earliest and worst victims of leaded gas; their immaturity makes them particularly vulnerable to systemic and neurological harm,” Kitman noted. According to Kevin Drum of Mother Jones, research has connected lead exposure in youngsters to “a whole host of issues later in life,” including lower IQ, hyperactivity, behavioral disorders, and learning disabilities. He adds that a large body of studies has linked lead exposure in youngsters to violent criminality. Much of the lead from the unleaded era is still present in places affected by gasoline fumes. Drum writes that this is a problem that can’t be put off for another generation.
Is leaded gasoline still available?
“It took two years to put lead into gasoline and 60 years to take it out,” a specialist investigating lead poisoning in children once said. It took a long debate between scientists, regulatory agencies, and industry to get a consensus on leaded fuel’s intolerable harm to human health. It appears that the world has finally turned a corner on the usage of this harmful chemical in fuel, according to recent encouraging news.
Lead has been used in gasoline since the 1920s, when tetraethyl lead was added to minimize engine knocking. Tailpipes in the UK emitted an estimated 140,000 tonnes of lead into the atmosphere between 1970 and the end of the century. The use of lead in petrol has been prohibited since 1999.
Lower-income countries, particularly Algeria the last holdout have found it more difficult to phase out lead. According to the United Nations, leaded petrol has been officially eradicated as of July 2021, which means it is no longer available for vehicles or lorries anywhere in the world.
Though lead-containing gasoline hasn’t been seen at UK station pumps this century, lead contamination remains a persistent threat. Lead was found in airborne dust collected in London between 2014 and 2018, over two decades after tailpipe emissions of the metal had stopped.