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We have seen that knowledge can “evaporate” our need for matter, but what of the other key component of progress: energy? While the invention of agriculture was an energy revolution of our stomachs, humanity would likely have remained agrarian if it were not for another energy revolution; one that fed the fires of our machines, the Industrial Revolution. Here, we chart the progress of engine technology, thermal efficiency, and how these heat machines changed our world and became increasingly efficient along the way.
As I discussed previously, technology is counter-entropic. It is the search for improbable combinations of atoms that work together in new, useful ways. In his book, More From Less,
writes that this requires a “crystallized” form of energy or power source. Until the Industrial Revolution, energy was largely limited to that which could be done by animal or human power. The key breakthrough to unlocking a future of growth was the capability to harness heat energy to do work.In the late 1600s, the idea that water could be heated into steam and used to make things move was not new. Indeed, thousands of years earlier, inventors had built devices that did just that. But these simple machines were little more than amusement pieces and curiosities. They were inventions, novel ideas that had unrealized potential. It took the hard work and ingenuity of engineers and entrepreneurs to find ways of transforming them into true innovations. And like most such innovations in the story of human progress, no single individual can lay claim to having invented them.
External Combustion
External combustion technology was the first to be commercialized. In external combustion, heat energy is directed into a medium (usually water) where it boils to do work. I begin this analysis with the Newcomen steam engine because it was the first heat engine to become widely used. Invented circa 1705, this simple steam engine was massive, inefficient, and difficult to operate. The design employed a piston in a cylinder that collected steam from the boiling of water using coal. The pressure of the steam pushed up upon the piston, at which point cool water was injected into the cylinder, creating a partial vacuum. This vacuum allowed the pressure of the air to push the piston back down to where the process could be repeated.
First installed commercially in 1712, the Newcomen engines were used primarily to pump water out of coal mines. They serve as a great example of how necessity breeds innovation but also the other way around. The machines enabled coal miners to explore deeper deposits for Britain’s rapidly growing coal demand and the machines themselves helped to fuel that demand with their voracious appetite of the fossil fuel. This was due to their poor thermal efficiency of roughly 0.5 percent. Thus, the Newcomen engines were generally only economically viable near cheap sources of coal.
It didn’t take long for some to address the Newcomen design’s limitations. In the 1760s, James Watt realized that most of the engine’s heat energy was wasted reheating the cylinder after it had been cooled. He designed a separate cylindrical condenser where cool water was injected, allowing the main cylinder to remain hot at all times. He also devised new seals, better machining techniques, and other innovations that increased thermal efficiency to between 2 and 3 percent. The first Watt engine went into operation in 1776.
Watt went on to further improve his design, developing a “double acting” engine by 1783, which admitted steam to both sides of the piston, alternating back and forth. This double action could be used to convert a simple “up and down” motion into a more useful circular motion with a broader range of use cases, including powering early factories. With the Watt engine, nascent factories could now operate their machines without the need to be located near sources of running water.
These early steam engines were “atmospheric,” most of the “work” was done by the weight of the atmosphere pushing down on a partial vacuum created when condensing steam. Watt and others remained resistant to using what was then called “strong steam” or high-pressure engines for safety reasons. But in theory, a strong steam engine could be more compact, lighter, and more efficient than an atmospheric engine ever could.
By 1811, continued technological advancement made high-pressure engines possible. The Cornish engine used high-pressure steam to push down on the piston (as opposed to atmospheric pressure), helped along by a vacuum underneath. This was aided by the advancement of boiler technology; new flued boilers were cylindrical and laid horizontally, and thus could take significantly more pressure than prior “haystack” designs.
By 1830, single-flued boilers gave way to multitubular designs that greatly increased the surface area in contact with water, heating the water into steam more efficiently. Additional improvements in design and materials more than tripled thermal efficiency to about 10 percent and made the steam engine compact enough for mobile applications. Enabling steam-powered ships and the first practical locomotives, including the famous “Rocket” (pictured below).
The last major iteration of the steam engine, the steam turbine, emerged in the closing decades of the 19th Century. Designed and promoted by Charles Algernon Parsons, the steam turbine eschewed pistons, and instead used hot high-pressure steam to rotate a turbine. This design breached over 20 percent thermal efficiency. The steam turbine was almost immediately put to use on ships enabling faster sea travel, but also became the method of choice for harnessing steam for the generation of electricity. Turbines began providing affordable electricity just as the first electric light bulbs were hitting the market.
Internal Combustion
Steam engines remained an important source of power into the 20th Century and through the so-called “Second Industrial Revolution,” but their limitations had been reached. Unlike the first, the second industrial revolution was not defined by coal and external combustion. It was instead driven by petroleum and internal combustion. Liquid petroleum could be refined into specialty fuels like kerosene, diesel, and gasoline and be easily transported via pipelines. Petroleum products emit fewer pollutants and about 30 percent less carbon dioxide for a given amount of energy compared to coal.
In addition, internal combustion engines could harness that energy more efficiently than external combustion because they removed the intermediary medium (water) and directly combusted the fuel instead. Like the steam engine and many other innovations, the history of internal combustion is convoluted with no clear “inventor.” It was instead a series of good ideas whose time had come in the latter half of the 19th Century.
Two basic engine designs would come to dominate. Both would direct a fuel/air mixture into a series of pistons where it was ignited, and the pressure used to draft a shaft connected to a flywheel. In diesel engines, pressure alone was enough to ignite the mixture. In gasoline engines, on the other hand, a carefully timed ignition spark was required. The first successful four-stroke engine, also known as the “Otto cycle,” began production in 1876.
These early engines were less thermally efficient than steam but were more compact, lightweight, and better suited to mobile applications. For this reason, gasoline won in a three-way race with steam and electricity to power the automobile that would go on to replace horses. More efficient diesel engines became the engine of choice for trucks, ships, and trains. But the single greatest achievement of internal combustion was the unlocking of powered flight.
While unpowered gliders had been experimented with for some time, powered flight was thought, by many, to be impossible due to the limitations of engine technology. This was among the primary challenges that the Wright Brothers faced. They needed a powerful, compact, and lightweight engine; something that steam simply couldn’t provide. In fact, at the time, internal combustion engines couldn’t either. The Wrights were forced to innovate and fashion a custom engine out of an aluminum block. In another example of how innovation can be self-reinforcing, it is notable that the Wright’s aluminum engine would have been impossible just a generation earlier.
Aluminum deposits on Earth are rarely pure, thus extraction of the metal was historically extremely expensive; aluminum was worth more than gold. By the turn of the 20th Century, however, aluminum prices had fallen due to the development of the Bayer refining process in 1889. This energy-intensive process was made possible by…you guessed it…the proliferation of relatively efficient steam-powered generation plants.
By the 1930s, internal combustion engines controlled the skies and broke past the efficiency of steam turbines. By the 1950s, diesel engines were achieving thermal efficiency ratings of nearly 50 percent, or roughly double that of the most capable steam turbines a few decades earlier. And like external combustion engines that began with pistons, internal combustion eventually found its way to rotating turbines as well.
The jet engine, simultaneously and independently invented in both Germany and Britain in the 1930s, used a turbine-driven compressor to compress incoming air where it was mixed with kerosene fuel and ignited. The high-pressure gasses drove a turbine that operated the engine while providing a forward propulsive force. Lacking pistons, jet engines created little vibration, reducing wear and tear, and enabling them to reach higher speeds. The jet turbine ultimately made air travel faster, safer, and affordable for the masses.
Atoms to Bits
Engine innovation did not stop there, but the vast leaps in thermal efficiency were over. In part, this is likely because we approached the physical limits of using heat energy to do work. At the same time, the third industrial revolution, the information technology revolution, focused more on bits instead of atoms. The IT revolution augmented our minds, not our bodies; it doesn’t take much energy to run a computer. Nonetheless, computers have been instrumental in designing new gas turbine blades and other engine parts, making them lighter, cheaper, and able to withstand higher pressure and heat.
In this era, a new fossil fuel is emerging front and center: natural gas. Natural gas continues a trend of decarbonization, emitting fewer pollutants and about 30 percent less carbon emissions for a given unit of energy. Engineers have also developed the Combined Cycle Gas Turbine to better harness this energy. Here, natural gas is ignited and used to drive a turbine, much like a jet engine. But instead of dumping the hot exhaust, the heat energy is then collected by water where it is transformed into steam and used to drive a separate turbine. CCGT devices have broken 60 percent thermal efficiency, providing low-cost, low-environmental impact energy for this new world of bits.
Charting all of this, we see that the “problem solving machine” has not only led us to rely on increasingly less carbon-intensive and less polluting fossil fuels, but our ability to extract energy from them greatly improved. I hope, and believe that this trend will continue with solar, wind, and nuclear helping to further mitigate the environmental impact of human progress. This is crucial because without energy abundance, there is no progress to be had at all.
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The future of fuel-to-energy efficiency is bright! Thermoelectrics could help capture more energy from waste heat and things like solid oxide fuel cells or companies like Lightcell energy might squeeze more energy out of fuels.
https://en.wikipedia.org/wiki/Thermoelectric_generator
https://en.wikipedia.org/wiki/Solid_oxide_fuel_cell
https://www.lightcellenergy.com/