The Electrification of Production Plants

What This Article Covers

  • Use of Fossil Fuels in Production
  • The Second Industrial Revolution
  • The Steam Turbine
  • The Growth of Power Stations
  • Understanding the Line Shaft
  • The Steam Turbine Improves and the Factory Changes

Factory Electrification


Fossil fuels and the growth of manufacturing that occurred during the fist and second industrial revolutions are often written about as separate phenomena, but in fact, they reinforced one another. The first industrial revolution was powered with by the localized combustion of fossil fuels. This greatly increased the power that was available to manufacturing and allowed production to be flexibly located, instead of having to find manufacturing next to natural energy sources, such as rivers. In Europe, mills, such as those designed for grinding grain, malt and meal were most often located next to rivers so that the waterpower could be harnessed to perform the grinding. However waterwheels — where the shaft was connected to gears and a series of belts and pulleys, was also used in manufacturing. In the first industrial revolution, most factories either had their on-site steam engine or a power building placed in the middle of small factories that could be rented, with a single steam engine powered a shaft for each rental factory that surrounded the power building.[1]

The Second Industrial Revolution

The second industrial revolution (marked by the assembly line and mass production) was powered by the far more efficient centralized combustion of fossil fuels at power stations. The first central power station was built in Surrey in the UK in 1881. In 1884 the invention of the steam turbine greatly improved the efficiency of power generation, particularly central power generation, which could more easily leverage the power generation economies of very large steam turbines.

The Steam Turbine

Steam Turbine

The steam turbine, which converts fossil fuel energy into mechanical energy — which is subsequently converted into electrical power was one of the technological advances that made the relatively efficient conversion of fossil fuels in both central power stations (that powered factories) and in ships and rail. As time passed the temperature of the steam used increased, as did the rotational speed of the shaft, and the size of the steam turbines. All of this lead to increased efficiency and lower electrical prices. Centrally run steam turbines run by power utilities can also be run continuously – the so-called base power, with peak power provided by internal combustion engines. Interestingly, a steam turbine is based on the same principle as the water wheel, humanity’s first attempt to leverage the mechanical power of the stored energy of the sun for purposes of manufacturing. 

The Growth of Power Stations

By 1890, there were 1000 central power stations in operation in the US and 3620 in 1902.

Growth in Electical Stations

This graphic shows the extreme growth industry that power generation was at one time. 

Growth in Power Sources

This graphic show has steam turbines, and partially internal combustion engines came to replace steam engines. Central power plants began with steam engines, just as were used in factories. However, the actual growth in the authority plants came with the introduction of steam turbines, which had tremendous economies of scale. Steam engines were one of the great growth areas of the economy up until roughly 1917.  Something else we can see from this graphic is that the power output from each steam turbine was larger than that for each steam engine, because even while power use is significantly increasing, the number of steam engines is declining rapidly, while the number steam turbines are increasing far more slowly. The rise of the steam turbine even displaces the rise in internal combustion engines (that is internal combustion engines for power generation, not internal combustion engines for transportation – which is not counted on this graph)[2]

Direct Versus Indirect Drives

This shows how electrical drives (unit drives) took over for direct drives in factories. From roughly 1919 being completely inconsequential in factories, electrically drive unit drives surpass direct drives (line shaft was driven) by 1920

This was enabled through the invention of electrification and the electrical grid. Electrification or the development of the electrical grid occurred from the 1880s to 1950 in the US and the UK. On-premises steam engines drove manufacturing machinery in 1900. However by 1920 electricity —  that is power generated from a distance which was produced, at first by a remote steam engine and then later by a remote steam turbine. A transition from engine to turbine being mostly complete by 1917 driving electrical motors on the factory floor, was more common in driving machinery than locally generated power. The growth of centralized power generation was very fast. By 1914 the power generated by electrical utilities surpassed all the power produced at factories in the US.

Understanding the Line Shaft

Before electrification, power was supplied from a steam engine through something called a line shaft. This was named so because there was a single main shaft in the factory. This concept goes far a back in time when similar systems were used to distribute power from a single source – such as an animal or waterwheel to multiple workstations.

Line Shaft

Notice the line shaft. The shaft here is multiple connected pulleys (the cylinders) which transfer the power to another pulley below which was connected to what was called the driving spindle, which the drives the machine.[3] A pulley not attached to the driving spindle was called the “idler” and was essentially neutral. The belt was put on the idler either when the operator needed to switch gears, or when the machine was not in use. Not consuming any of the power from the steam engine. However, the top pulley still needed to turn, and any turning pulley still consumed energy in the form of friction. It is estimated that the power loss across the shaft was normally more than 25%, and roughly 1/3 to 2/3s of the power created in the factory’s steam engine was consumed in the friction of turning the various shafts. From their invention, many improvements were made in the belt (changed to rope) and to the pulley (The diameter of the pulleys were increased to improve mechanical efficiency.)[4]

Different pulleys would be connected to multiple workstations. Any single shaft could run close to the width of the factory. Belts could connect shafts together so that rows shafts with workstations at each row. Some factories reached more than mile of line shaft. The Queen Street Mill had 600 looms driven by a single 500 horsepower coal-fired steam engine.[5] Clearly, the line shaft design would have limited the layout of the factory because the machine layout had to partially be based up the limitations of the shaft locations and the belts.[6]

Multi Drum Belts

Here is how power was transferred from one shaft to another. The workstations had different “gears” based upon different circumference lower pulleys, which the belt could be transferred to the receiving side.

If a manufacturing item had a few number of single workstation types the line shaft method of power distribution was not all that complex to design. However, other manufacturing environments there were both many machines and a great variety of machines – and this means a complex design for distributing this power from a single source of power in the factory.

The Rise of Electrification

With the rise of electrification, local electrical motors enabled unit drives. Unit drives – which were connected directly to the drive shaft of the machine greatly reduced the power loss caused by the multiple shafts, belts, pulleys and transfers between shafts. They’re as also no power loss in turning pulleys for machines that were not being operated. This transition from line shaft driven factories was not smooth. Machines that had been designed to be powered by belts and shafts had to be redesigned to accept input from the electrical motors. Existing factories needed to be reconfigured, the plant layout philosophy had to be rethought. The many implications for the change in how power was delivered to factories was a major adjustment that took decades to sort out in a way that the new and more convenient and sophisticated power source was fully leveraged for manufacturing efficiency. It drove improvements in many areas, as well as evolved as new improvements from many areas (such as improved metallurgy and machine tools) were incorporated into successive new factories and factory retrofits. In fact, the Detroit Edison Company, in 1905 lent motors to manufacturers and then performed the installation to properly apply the motors.[7] In essence, the power company was providing consulting along with their motors. They undoubtedly did this because they knew the value of the motors, knew they would drive electrical consumption, and also knew that the manufacturers for which they installed the motors could not do it themselves.

What became clear is that the electric motor and the tool needed to be essentially designed for each other. These are capabilities that we all take for granted today. For instance, when we buy a laptop or cellphone, we receive a power supply (and battery) that has been designed specifically for the needs of that item.

As I will describe in the next article, the power benefits to electrification and unit drive was just one small part of the overall value proposition.

The Steam Turbine Improves and the Factory Changes

As more advancement occurred in steam turbines, the cost advantage continually migrated to the central production of power. In fact, according to the publication From Shaft to Wires, it was not even the primary motivation. This is because the cost of electricity was generally around .5 to 3 percent of the total production cost of the item. However electrically delivered remote power allowed for the following:

  • Reduced the fire hazard of having a power generator right in the factory. This lowered risk allowed manufacturing companies to build much larger buildings, without the concern that a local power generation fire could consume the entire building — and this lead to further increases in manufacturing efficiency.
  • A factory of the same size could hold more productive machinery if it did not need to have a power plant contained within it. 
  • At first, electrical power was used in manufacturing environments where cleanliness was more critical such as textiles. This was a switch between power sources, but not much else. However, as time passed companies began to take advantage of electrical power in ways that made the plant layout more efficient. “Machinery could be arranged on the factory floor according to the natural sequence of manufacturing operations, minimizing the handling of material. The ability to arrange machinery irrespective of shafting made all space in the factory equally useful and not only for storage, as heretofore.” – From Shaft to Wires
  • The manufacturing environment improved “Lights could be provided in spaces formerly occupied by belts, pulleys, and shafts. Factories were vastly cleaner and brighter after the adoption of the unit drive (electrification), and many observers felt this had a very positive impact on the quantity and quality of work.” -From Shaft to Wires
  • With the removal of overhead shafts, cranes could be used to perform lifting that was previously performed manually. Cranes have a very positive effect on factory productivity.
  • Unit drive improved the ability to perform precision manufacturing and to have less waste. It eliminated one of the major problems, which was belt slippage.
  • Productivity was enhanced with a unit drive as there was much more control over the drive speed of the machine. While pulleys had few gears, unit drives had a gearbox, which could be increased and decreased in rotation far more incrementally. This allowed the speed to be matched very carefully with the best speed for the manufacturing process. This was very much true with direct current motors. However with the introduction of alternating current electrical motors which had some advantages over direct current motors, and the fact that alternating current was increasingly supplied because of its easier transmit ability over distance, the alternating current induction motor was introduced.[1]
  • Instead of having to run power through the entire factory to just power a group of machines, any group of machines could be run independently of the rest of the factory. On the other hand, any group of machines could be turned off.
  • Without concern for the requirements of housing a power plant in the building, factories could be built more simply and less expensively.
  • Electrically driven motors were more efficient than single shaft steam engines regarding the reduced shafting the reduced number of belts.
  • Factories could be built in more geographic locations than they could previously, as power could be delivered to any location where the power grid reached. “…large factories did not have to be located adjacent to sources of water power, nor did they have to be designed for a large steam engine if it was particularly inconvenient to supply the engine with coal.” From Shafts to Wires
  • Electrification also meant more uptime, as the entire factory was not dependent upon a single line shaft. This was true in two different but related ways. First, the power from the central power plant was more consistent and reliable than power generated locally at the factory.
  • Henry Ford leveraged electrification in all of these dimensions when he introduced the most automated assembly line to date in his automotive factory. Henry Ford is on record as saying that he could not have setup his assembly lines, at least the way that he did, without electrification.
  • Ford was certainly not the only one to adjust their factories, electrification of factories changed factory layout in many different areas, and not only for assembly line operations.

As the graphic above shows, centralized power generation became so efficient – and the ability to transport energy so much easier with the development of alternating current — that is becoming more efficient to import and export power between areas serviced by a centralized power plant rather than increasing production at one power plant. That is continuous production —  but at specific level, was simply so efficient, that it made sense for the construction of power plants to build in excess capacity, which could be sold and sent to other regions during periods of low power consumption, and to buy power when the opposite was the case. Unbelievably, power is now shared across countries and even across continents. Some plants are referred to as base load plants and are in continual operation – which includes nuclear and coal-fired. Other plants are called peak power plants — which are powered with higher cost energy sources such as natural gas power plants which can perform batch power generation — bringing up power when needed and cycling down when it is not. Even across thousands of miles, energy can be transported at roughly 1/2 the cost of its generation. Therefore, it simply makes sense to sell energy to the grid if a power plant has excess and vice versa. Electricity can be transferred at very close to the speed of light — therefore transmission from any point to any point — as long as the transmission lines exist, can handle the load and are in good functioning order — can occur essentially instantaneously.

Long distance power lines enabled power stations to connect to one another and to manage and balance the load by sending energy — at a cost — across these lines.

Not only was fossil fuel deeply connected to the first and second industrial revolutions, but the method of generation and delivery of this energy changed the configuration of manufacturing, with electrification (the delivery over distance of the combustion of fossil fuels) enabled the development of non-water powered assembly lines. (see more here)


[1] An induction motor is an alternating current motor where the electric current is induced with by electromagnetic induction from the magnetic field of the stator winding. Induction motors that pre-dated semiconductors were difficult to scale up or down the rotation of the shaft.


February 26, 2013

July 27, 2013
The 1960s: Isolated Systems

July 12, 2013

May 27, 2013

August 1, 2013

July 27, 2013

July 27, 2013

July 25, 2013

From Shafts to Wires: Historical Perspective on Electrification, Warren D. Define, Jr., Journal of Economic History, Volume 43 Issue 2 June 1983

July 21, 2013

July 18, 2013

July 22, 2013

July 22, 2013

July 15, 2013

May 22, 2013


[1] This design continued into the second industrial revolution, but the power building’s steam engine was replaced with electricity, and a connection to the central power station miles away.

[2] Statistics from Electrical Power in American Manufacturing 1889 – 1958, Richard B. Duboff, University of Pennsylvania, 1964

[3] I use the term “top” or “bottom” pulley, but that just the design pictured previously. Mostly line shafts were above the machinery, but not always. There are also examples of underground shafts or even vertical shafts.

[4] Wikipedia

[5] Wikipedia

[6] This shaft is from Queen Street manufacturing. This factory was built in 1894. This is early transitory period between line shafts and electrification. Courtesy of Clem Rutter and Wikimedia Commons.

[7] From Shafts to Wires

Leave a Reply 0 comments