Contributed by Todd Perry, Principal, PPM Consultants
The history of gasoline and octane additives mirrors technological advancements, evolving public health knowledge, and environmental awareness. Initially a byproduct of oil refining, gasoline rose to prominence with the invention of the automobile in the late 19th century. As car engines became more powerful, the need for octane additives to prevent engine knocking became paramount. The story of gasoline’s evolution is also the story of how octane additives, once dominated by toxic substances like lead, have shifted toward more sustainable and environmentally friendly alternatives such as ethanol.
The Early Days: Gasoline as a Waste Product
When Edwin Drake drilled the first oil well in Pennsylvania in 1859, gasoline was not the intended product. Oil was distilled for kerosene, an essential fuel for lamps. Gasoline and other light petroleum products were discarded because they had no practical use at the time. It wasn’t until the invention of the automobile in the 1890s that gasoline found its place as a valuable fuel. By the 1920s, gasoline-powered vehicles had become the standard, and the fuel was in high demand.
The Role of Octane in Gasoline
As engines became more sophisticated, engineers realized that gasoline needed to burn at a specific rate to avoid engine knocking, a condition where fuel combusts unevenly, causing a rattling sound and potentially damaging the engine. This need led to the development of octane ratings, a measure of a fuel’s ability to resist knocking. Fuels with higher octane ratings allow engines to operate more efficiently and with higher performance. In the early 20th century, the search for an effective and cheap octane booster began.
Gasoline: A Toxic Solution
In 1921, engineers at General Motors discovered that tetraethyl lead (TEL) could be used to boost the octane level of gasoline, significantly reducing engine knock. Leaded gasoline quickly became the standard fuel in the United States and around the world. However, it didn’t take long for the public health consequences of lead exposure to become evident. Workers in TEL production facilities began experiencing symptoms of lead poisoning, and it was clear that lead in gasoline posed a serious health risk.
By the 1960s, studies showed that even low-level exposure to lead, particularly in children, could lead to developmental issues, including lower IQ, learning disabilities, and behavioral problems. Lead exposure also caused cardiovascular problems in adults. Despite the known risks, leaded gasoline continued to be widely used until the 1970s, when mounting pressure from public health advocates led to its gradual phase-out in the United States. The Clean Air Act of 1970 marked the beginning of this process, and by 1996, the use of leaded gasoline in on-road vehicles was banned.
The Rise and Fall of MTBE
As lead was phased out, the petroleum industry needed a new octane booster. Methyl tertiary butyl ether (MTBE) became the preferred alternative during the 1990s. MTBE raised octane levels and helped reduce emissions, making it a popular choice in reformulated gasoline designed to meet new air quality standards under the Clean Air Act Amendments of 1990.
However, MTBE has proven to have its own environmental issues. Its high solubility in water meant that when gasoline containing MTBE leaked from storage tanks or spilled during transport, it dissolved readily into water and therefore migrated off site contaminating groundwater supplies. By the early 2000s, numerous states had reported widespread water contamination, and the EPA began phasing out MTBE. Ethanol, a biofuel made from corn and other plant materials, emerged as the primary replacement for MTBE.
The BTEX Complex and its Health Impacts
Another octane-boosting alternative to lead and MTBE was the BTEX complex—a combination of benzene, toluene, ethyl-benzene, and xylene. These aromatic hydrocarbons are derived from petroleum and have high octane ratings. However, like their predecessors, they came with significant health risks. BTEX compounds are volatile organic chemicals, and their combustion produces harmful byproducts, including polycyclic aromatic hydrocarbons (PAHs) and ultra-fine particulates (UFPs), both of which are known carcinogens.
Exposure to BTEX compounds has been linked to respiratory problems, cancer, and developmental issues. In response to these risks, the EPA began regulating benzene levels in gasoline in 2007, capping it at 0.62%, while the other aromatic compounds in the BTEX complex remain regulated at various levels.
Ethanol: The Cleaner Alternative
Ethanol, a plant-based biofuel, has long been considered a potential alternative to gasoline. Henry Ford, the famous automobile pioneer, was an early advocate of ethanol. He designed the Model T to run on ethanol, envisioning a future where fuel would be produced from renewable agricultural products. However, gasoline’s lower cost and the petroleum industry’s dominance pushed ethanol out of favor until the 1970s.
During the oil embargo of 1973, when gasoline prices soared and fuel shortages hit the U.S., interest in alternative fuels, including ethanol, was reignited. The U.S. government began promoting ethanol as a way to reduce dependence on foreign oil and lower greenhouse gas emissions. Ethanol blends, such as E10 (10% ethanol, 90% gasoline), became standard, and today, more than 95% of gasoline sold in the U.S. contains ethanol.
Ethanol’s Role as an Octane Booster
Ethanol is an excellent octane booster, with a rating of over 100. Refiners often produce sub-octane gasoline, which is then blended with ethanol to raise the octane rating to the level required for retail gasoline. This process, known as ethanol blending, was the markets default replacement of the more harmful octane boosters like lead and BTEX compounds.
In addition to its high-octane rating, ethanol burns cleaner than petroleum-based additives, reducing the emission of harmful pollutants like UFPs and PAHs. Studies have shown that increasing the ethanol content in gasoline from 10% to 15% could reduce cancer risks associated with emissions by 6.6%. Ethanol also has lower lifecycle greenhouse gas emissions compared to gasoline, making it a more sustainable fuel.
The Future of Gasoline and Octane Additives
As the world seeks to reduce its reliance on fossil fuels and cut greenhouse gas emissions, ethanol’s role in the gasoline supply will likely expand. Automakers and policymakers are exploring higher ethanol blends, such as E15 (15% ethanol) and E30 (30% ethanol), which would allow for even more significant reductions in emissions while maintaining high engine performance. A national transition to mid-level ethanol blends, such as E25 or E40, could further lower consumer fuel costs and reduce dependence on petroleum.
The transition to higher ethanol blends would also enable the design of more efficient engines, which could operate at higher compression ratios, further improving fuel efficiency. Ethanol’s renewable nature, combined with its ability to boost octane and reduce harmful emissions, makes it a key player in the future of transportation fuels.
Conclusion
The history of gasoline and octane additives reflects the evolving priorities of the automotive and energy industries. From the toxic days of leaded gasoline and MTBE to the cleaner promise of ethanol blending, each step has been driven by the need for more efficient, cost-effective, and environmentally friendly fuels. Ethanol stands as a renewable alternative to petroleum-based additives, contributing to reduced emissions and energy independence.
However, ethanol brings its own set of challenges. The cost of refining ethanol is nearly double that of gasoline, and without the financial value generated by EPA Renewable Identification Numbers (RINs) through the Renewable Fuel Standard (RFS), its economic viability is difficult to sustain. Ethanol’s hygroscopic nature also poses risks, as it absorbs water from the atmosphere, leading to phase separation in fuel. This can result in water contamination, corrosion, and leaks, especially in equipment that isn’t ethanol compatible. Furthermore, ethanol has about 33% lower energy density than gasoline, which reduces fuel efficiency in vehicles running on higher ethanol blends. Additionally, the widespread use of corn for ethanol production raises concerns about food prices and agricultural land use.
Thus, while ethanol offers environmental benefits, it requires careful management to address its economic, environmental, and technical challenges. The future of gasoline will depend on balancing ethanol’s promise with the practical realities of its impact on the fuel supply.
Sources
- S. Energy Information Administration – “History of Gasoline”
- Kendrick Oil – “The History of Octane Additives (Besides Lead) In The United States”
- Energy Resourcefulness – “History of Ethanol Used as a Fuel in Internal Combustion Engines”
- Fact Sheet – “A Brief History of Octane in Gasoline: From Lead to Ethanol” by Jessie Stolark