Lead is an essential raw material in the production of numerous essentials from car batteries to aviation fuel thanks to its malleability and anti-knock properties. However, over the years, scientists have exposed the toxic nature of lead and its adverse effects on our environment.
In 2014, 12 people lost their lives as a result of lead poisoning in the Flint water crisis. Ever since, the toxicity of the element has become more of a well-known fact. This then begs the question, if lead is as toxic as scientists have demonstrated it is, why does aviation fuel have lead in it?
The case for lead as an additive in aviation fuel is quite a complicated issue. In simple terms, lead is used in aviation fuel because its anti-knock properties enhance the octane rating of aviation fuel, which is necessary for the efficient combustion of fuel.
Although aviation engineers agree on the toxicity of lead, it is difficult to ignore the obvious advantages lead offers aviation fuel.
As already stated, it is difficult to just dismiss lead as a toxic substance in the face of the numerous gains it offers us in aviation. Therefore, to understand the use of lead in aviation fuel, as aviation enthusiasts, we must take a wholesome approach in examining these benefits as we also look into its adverse effects on the environment.
In a bid to achieve a deeper understanding of this subject matter, we will explore the complexities surrounding the use of lead in aviation fuel. Going beyond the reason for the continued use of lead in aviation fuel, we will touch on the pros and cons of using lead, and its exact effects on the environment.
Table of Contents
The Benefits of Using Lead in Aviation Fuel
Lead is a very malleable metal, which is ductile, dense, and a poor conductor of electricity. These characteristics, coupled with its valuable anti-knock properties, make it a very important additive in aviation fuel.
Lead offers aviation fuel a wide range of benefits. These benefits also stand as the reason why lead has become so hard to phase out in the aviation industry despite its obvious shortcomings. That said, the benefits of using lead in aviation fuel include:
- Octane rating enhancement: The octane rating of a fuel defines the combustion efficiency of that fuel in a combustion chamber. In other words, it is a measure of the performance of this fuel as it burns in a combustion chamber. Lead in the form of tetraethyl lead (TEL) is used as an additive in aviation fuels to improve or increase their octane ratings.
- Combustion regulator: The presence of lead in aviation fuels allows it to serve as a combustion decelerating agent. This benefit prevents the premature ignition of the fuel-air charge in the combustion chamber.
- Efficient combustion of fuel: The slower combustion benefit provided by lead (TEL) in aviation fuel means that the fuel expands more during ignition, thus leading to smooth and efficient combustion.
- Anti-explosion: Owing to the possible presence of impurities in aviation fuels, they can still be prematurely ignited in the combustion chamber and explode. Lead serves as a shield and an anti-explosion agent in the event of pre-ignition. This benefit helps to prevent damage in the engine.
- Engine cycle efficiency: Thanks to its benefit as an octane rating enhancer, the presence of lead in aviation fuel increases its useful compression ratio or supercharge ratio, thus leading to a more efficient engine cycle. In other words, the fuel can be
Adverse Effects of Using Lead in Aviation Fuel
Despite the obvious advantages of using lead in aviation fuel, it also poses a number of challenges. Although there is no real technological disadvantage to the airplane caused by the presence of lead (TEL) in aviation fuel, TEL emissions pollute the environment with lead, which can be inhaled or ingested by humans. Lead in all forms is a toxic substance and can cause adverse effects on humans.
A few of these effects on humans include:
- Breakdown of nervous systems and immune systems: If inhaled directly into the system of adults, lead in all forms can cause a breakdown of the nervous system. This breakdown is a result of lead’s ability to mimic and limit the actions of calcium in the body. After paralyzing the nervous system, it goes ahead to attack the red blood cells and immune systems of the body.
- Poor muscle coordination: The breakdown of the nervous system caused by the presence of lead in the body leads to poor muscle coordination in infants or muscle and joint pains in adults.
- Learning disabilities and decrease in IQ: Studies have demonstrated that children are more sensitive to lead poisoning as it leads to various adverse effects in their bodies. One of these adverse effects is the emergence of learning disabilities and a reduction in IQ. Infants exposed to lead in any form, especially in very high doses, have manifested learning disabilities and low IQs over the years.
- Harm to a fetus: When a pregnant woman inhales a lethal dose of lead, it leads to a breakdown of her nervous system, red blood cells, and the immune system as stated above. Consequently, the breakdown of her systems can cause great harm to her fetus including brain damage or death in extreme cases.
Why Has Lead Not Been Phased Out Yet?
Since scientists and aviation engineers agree on the toxic nature of lead, there has to be a good reason why its use is still sustained in aviation fuel.
However, from politics to the benefits of lead in aviation fuel and the need to re-train chemical engineers in this practice, so many factors come into play when we try to explain the reason why lead has not been phased out yet.
Above all, the phasing out of lead is a question that comes down to predicting the emergence of a replacement for Lead as a vital fuel additive.
Although so many researchers have carried out various studies on the phasing out of lead in aviation fuel, the following count as the major factors that must be considered:
- The slow emergence of a viable alternative: Scientists have not come to a general consensus on an alternative for the replacement of lead. This has led to the slow emergence of a viable alternative that will replace lead as an important aviation fuel additive.
- The lack of political will by governments: Most governments lack the political will to create policies that will fast-track the replacement of lead.
- The lack of fiscal incentives: Virtually no fiscal incentive or policy exists that will create the right atmosphere for an alternative fuel additive to strive.
- The lack of price incentives: Money is a major factor in every project. Currently, there are no price incentives to encourage investors to invest in an alternative fuel additive.
- Lack of general consensus: No general consensus exists among major stakeholders in the aviation cum aviation fuel industry on the phasing-out of lead in aviation fuel.
- The lack of public sensitization and education on the issue: It took public awareness for the dangers of global warming to be discussed on the political stage, such an awareness will be needed to create an urgency that will eventually move world governments to take active steps in the phase-out of lead in aviation fuel.
Jet Fuel and Av-Gas
Although much has been said about the use of lead in aviation fuel, it is important to stress that the only aviation fuel type that currently adopts lead as an additive is Aviation gas (Av-Gas).
Therefore there is a need to draw a distinction between Jet fuel and Av-Gas.
Jet fuels
Jet fuels are kerosene-based fuels rich in hydrocarbons with high enough octane ratings to run compression or turbine engines. This aviation fuel type does not need lead additives because it already possesses an octane rating that is high enough to ensure efficient combustion in combustion chambers. Although they are more unstable than Av-gas, their combustion efficiency makes them a good choice for big commercial flights.
Av-gas
Av-Gas, on the other hand, is a gasoline-based fuel. Gasoline on its own has a low octane rating. However, with the addition of TEL, Av-Gas possesses a higher octane rating than normal car gasoline. Its anti-knock properties provided by the presence of lead makes it a stable and very reliable fuel.
Furthermore, its stability, safety, and reliability in most environments make it most suitable for small piston-powered aircraft used for a select number of purposes that require a lot of maneuvers. These aircraft include light aircraft like Cessna 172 Skyhawk, Aviat Husky, Rockwell Commander, and so on.
Summary
In summary, it is evident that lead as a vital additive to aviation fuel (Av-Gas) is essential in aviation. Therefore, it would be counterproductive to rush into phasing this vital resource out. Consequently, scientists, engineers, and aviation enthusiasts must be willing to take a wholesome look at the issue and come up with effective and efficient ways of finding an alternative to lead that will not just increase octane ratings but be good enough to ensure smooth and environmentally safe combustions.
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