Tesla versus Edison: the conflict that gave us alternating current

The nineteenth century was the time of the great inventors. It was an exciting period, full of scientific advances, during which the vigorous development of capitalism caused struggles and confrontations between different ideas and patents.

One of these battlefields was electricity, where two very different visions clashed: Nikola Tesla, the proponent of alternating current (AC) and Thomas Alba Edison who advocated direct current (DC). But before the battle began, which the newspapers of the time called "The War of the Currents", some context is required.

Direct current and alternating current

Without going into too much technical detail, suffice to say that matter is formed by atoms and that their outer layers contain electrons that are only loosely attached to the nucleus of the atom. This means that they can leave, going from one point to another and generating electric current as they do.

All electric current is a flow of electrons that travels from a positive pole to a negative pole. These electrons flow differently in direct current and alternating current:

• Direct current: does not vary in time, since the flow is stable and unidirectional. It is the current stored in batteries.
• Alternating current: this flows cyclically, fluctuating in magnitude and direction at regular intervals. This is the current that travels through the power lines to the sockets in our homes.

The main advantage of direct current is that it tends to be safer than alternating current. It requires less insulation and lower voltages can be used. It also has the advantage that it can be stored in batteries.

The main advantage of alternating current is that, when transmitted over long distances, less energy is lost than with direct current. It is also easy to transform it into direct current.

The birth of a rivalry

Nikola Tesla, of Serbian origin, was born in 1856 in a small village in what is now Croatia. With a brilliant mind, at the age of 25 years he got his first job as an engineer in Hungary. From there he moved to France, where he worked in a subsidiary of what would be his biggest rival, Thomas Edison. In 1883 his huge talent took him to the United States to work with Edison himself.

The American, six years his senior, was already a highly prestigious inventor. He had just perfected and patented the light bulb. These two geniuses soon clashed.

In those years, electricity was making qualitative and quantitative strides. Demand was growing, larger power plants were being built and more energy needed to be transmitted over increasingly long distances. The vast American West needed to power ever larger cities and industries.

Thomas Edison advocated direct current, a more expensive and inefficient system due to dissipation of part of the energy in the form of heat. Nikola Tesla, on the other hand, was in favour of alternating current. The war began.

The war of the currents

Tesla proved that Edison's direct current was more expensive and inefficient. The greater the distance, the more energy was lost along the way. Tesla presented his own system as an improvement: alternating current.

Tesla's idea meant that electricity generated in the power plants could be increased to high voltage and transmitted over huge distances with hardly any energy loss. Once it reached its destination, it would be easy and cheap to use transformers to distribute it at medium and low voltage. This is the system used today to deliver energy from a power station to your home.

The rivalry between Tesla and Edison was more than a battle of ideas. It was also a financial war between companies. Thomas Edison allied with J.P. Morgan, the most powerful banker in the United States, to electrify the entire country with direct current. This was the beginnings of the almighty General Electric. Nikola Tesla created the Tesla Electric Company and partnered with inventor and entrepreneur George Westinghouse Jr.

Edison knew that his system was less efficient, but it would have meant losing huge sums of money. The Tesla company started winning more and more contracts, since the advantages were clear. But he encountered a serious obstacle: there were several fatal accidents involving engineers and operators, due to the high voltages of alternating current. Edison's side used each death as an excuse to discredit Tesla and his alternating current with the help of several widely-read newspapers.

These dirty dealings included circus-style public demonstrations, with Edison's supporters first applying a mild continuous current to an animal, leaving it stunned. Then they applied high voltage alternating current and electrocuted it. The intention was to spread panic about the consequences of electrifying the country with alternating current. Edison himself stooped to writing alarmist articles in which he described alternating current as a "constant threat" to homes and people.

Tesla's cause was not helped by the fact that during these years the electric chair was invented (patented by Edison's company) which used alternating current to execute condemned prisoners. The propaganda war was lost. It was fast and it was noisy.

However, as the years went by, alternating current was adopted as the best system to electrify the country, with additional safety measures on power lines and at substations. It was the system chosen for Chicago World's Fair in 1893 and for the electrical installations at Niagara Falls.

Tesla did not enjoy the fruits of victory, having been obliged to sell his patent to Westinghouse. But in the end Edison's company, already renamed General Electric, implicitly admitted defeat by applying for a Westinghouse patent license to use alternating current in its electrification projects.

Two geniuses in old age

The end of this "war" did not lead to peace between these two scientists - quite the contrary. In 1912, Nils Gustaf Dalén won the Nobel Prize for Physics in 1912 for inventing the solar valve which would switch the flame of street lamps on and off automatically at sunset and sunrise. There were rumours in the scientific community that the prize went to a "minor inventor" because of Tesla's refusal to share the Nobel with Edison for both their achievements in the field of electrical energy.

What happened to both geniuses? Although he "won" the war, Tesla was consigned to oblivion. He continued to devote his time to science, achieving developments such as the Tesla coil and wireless lighting - "extravagant" inventions. His ideas were ahead of their time and he failed to translate them into practical advances. He died penniless, the picture of a reclusive, eccentric scientist.

In contrast Edison became a millionaire thanks to dozens of patents such as the light bulb and the phonograph. He became one of the best known and admired inventors in history. Only in recent years has Tesla, whose name has been given to the best-known make of electric cars attracted renewed attention.