What Is a Spark Plug? A Look at Its History

What Is a Spark Plug? A Look at Its History

A spark plug is a component that ignites the air/fuel mixture in an internal combustion engine. It accomplishes this by means of an electrical current crossing an air gap between two electrodes, causing a spark.

In other words, spark plugs play a crucial role in keeping your engine running. Without spark, the air/fuel mixture cannot ignite, halting the engine in its tracks. It is important to acknowledge the three fundamental things a gasoline-powered internal combustion engine needs to run: Air, fuel, and spark.

Knowing the answer to the question "what is a spark plug"? is only part of the story, however. Let's go in-depth about the history of spark plugs, their usage and innovation, and potential alternatives.

Who Invented and Introduced the Spark Plug?

Perhaps surprisingly, there is no clear answer to who invented the spark plug! Some sources point to a man by the name of Edmund Berger.

Berger was an African who immigrated to France and supposedly invented the spark plug in the year 1839. However, it is important to note that the internal combustion engine emerged in 1860, years after the supposed original spark plug.

Because Berger never patented his invention, it is unclear if it existed, and if it did, many historians believe it would not resemble modern spark plugs and would most likely have been experimental. Also, it preceded the internal combustion engine, so the plug itself could not have been designed for engines as we understand them.

Spark plugs as we understand them today were invented by German engineers Gottlob Holnold and Robert Bosch in 1901 and patented in 1902. However, others also had a hand in the development of the spark plug over the years.

What Was the First Engine with Spark Plugs?

The first internal combustion engine was invented in 1860 by Jean Joseph Etienne Lenoir, a Belgian-French engineer. This engine included spark plugs, powering a single cylinder, three-wheeled vehicle that could move at speeds of up to 2 miles per hour. While this sounds incredibly slow, it was quite a feat at the time.

This is arguably the very first engine with spark plugs, at least that we know of, because it is the first known internal combustion engine, and Lenoir held patents both for the engine itself as well as the spark ignition system. Moving on, all internal combustion engines had spark plugs, because the very design of the engine itself necessitated the presence of spark plugs.

What Major Innovations Have Been Introduced to the Spark Plug Since its Invention?

While what a spark plug does has been consistent, what a spark plug is has varied in terms of construction over the years.

Spark plugs, as mentioned above, use electrodes. Initially, these electrodes were made of nickel. However, they were not very efficient or long-lasting, needing to be replaced every 1,000 miles or so.

Additionally, the original spark plugs were created for low powered engines that operated with little compression and much slower speeds than modern vehicles. They were simply not designed to handle the types of conditions we regularly expect spark plugs to excel in today.

Over time, other materials were used, copper, platinum, and iridium. These different alloys have enabled greater efficiency and longevity of spark plugs as compared to the original design.

For example, copper electrodes were commonly used in older cars (think prior to 1980). Normally, only the center of the electrode was actually copper, and the surrounding material was nickel because the copper would otherwise melt due to the high temperatures generated while running the engine. Copper spark plugs were also less efficient, requiring more voltage to produce a spark than other materials did.

Another innovation came with platinum spark plugs, able to last up to 100,000 miles and much more durable than their copper counterparts. While platinum spark plugs are still used and by no means obsolete, iridium spark plugs are a further upgrade, tougher than even the platinum plugs as well as much more effective (they typically result in better, or more complete, combustion, than other types of spark plugs).

Along with these improvements in electrode construction has also come insulator and thermal conductivity enhancements. Without going deeply into the science behind this, it can most simply be described as engineering advancements leading to better materials being used not only on the electrodes but the entire spark plug in ways that only serves to increase the lifespan, durability, and efficiency of the plugs.

What Are the Alternatives to Spark Plugs?

If talking about a gasoline powered internal combustion engine, there are no alternatives to spark plugs. They are vital for the engine to run at all, because the spark created by the plug is the thing that ignites the air/fuel mixture.

However, there is research into alternatives. One such project involved using lasers. Laser spark plugs were designed and used to power an engine successfully. The engineers involved explained that the use of lasers means no need for a electrode protruding out, leaving more space in the combustion chamber, and several laser beams can be used at once to result in more complete combustion.

While laser spark plugs definitely sounds interesting and could indeed be something that is more widely used in the future, as of right now we are limited to the traditional spark plugs, at least for gasoline powered engines. Diesel engines, on the other hand, do not use spark plugs at all! Instead, they use something called a glowplug.

Glowplugs do not fire the entire time a diesel engine is running, instead only being used during ignition. The reason diesel engines can get away without spark plugs is because diesel fuel requires lower temperatures for ignition to occur than gasoline does, so the engine uses only compression and the glowplugs (which contain a heating element at their tip) to ignite the air/fuel mixture.

How Do Glowplugs Differ From Spark Plugs?

There are several differences between glowplugs and spark plugs:

  • Spark plugs are required for gasoline powered internal combustion engines, while diesel engines require glowplugs
  • Spark plugs operate the entire time the engine is running, while glowplugs are only needed during the initial ignition process
  • Spark plugs use electricity to create a spark and ignite the air/fuel mixture, while the glowplugs heat up and thus provide heat to the compressed air/fuel mixture, which then ignites
  • Spark plugs are absolutely necessary for a gas powered vehicle to start, while diesel engines can start even without functioning glowplugs if the outside temperatures are high enough

Do Electric Vehicles Use Spark Plugs?

Electric vehicles, like diesels, have no use for spark plugs, but for totally different reasons.

While a fully electric car appears similar to gas powered ones, it is missing an internal combustion engine altogether! Instead, it relies on batteries to function, removing the need for spark plugs as well as all other components that make up the engine.

It is important to note that hybrid vehicles still maintain an internal combustion engine and therefore will utilize spark plugs when the engine, as opposed to electric motor, is being used.


Clearly, the question "what is a spark plug?" can be answered by simply stating that it is the part of a vehicle's engine that keeps it running, but there is much more to the story. Spark plugs have been around since the middle 1800s, but do not appear to have reached their modern design until at least 1901. Moreover, this design has by no means spelled the end of the spark plug's journey.

Engineering research and innovations have led to using different materials for spark plugs, as well as perfecting their overall construction to make modern spark plugs much better than their original counterparts. For instance, these improvements have quite literally extended the lifespan of a spark plug from around 1,000 miles to over 100,000 miles!

As of today, the spark plug is still the only option for an internal combustion engine that runs of gasoline, although there are plenty of variations in the types (for example, copper, platinum, and iridium spark plugs) you can buy. Furthermore, there is research on alternatives to the spark plug, including using laser plugs. In fact, laser plugs have been used successfully in an experimental manner!

While no alternatives are fresh on the market for gasoline engines, other engines do not use spark plugs at all. Diesel engines do not require spark plugs due to diesel fuel being able to ignite at lower temperatures than gasoline. Diesel engines thus use glowplugs which help heat up the air/fuel mixture which ignites with compression alone, and only needs glowplug assistance during the starting of the vehicle, and not continuous operation like spark plugs which are used the whole time the engine is running.

Hybrid vehicles still rely on spark plugs for the engine portion of the vehicle. Fully electric vehicles, on the other hand, are able to operate without any plug whatsoever because these vehicles literally have no engine, using battery power instead.