Coal in the Industrial Revolution and Beyond

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Coal was formed during the carboniferous period - roughly 360 to 290 million years ago - from the anaerobic decomposition of then-living plants. These plants ended up as coal because, upon their death, they failed to decompose in the usual way, by the action of oxygen to form eventually CO2 and water. As the carboniferous plants died, they often fell into oxygen-poor swamps or mud, or were covered by sediments. Because of the lack of oxygen they only partly decayed. The resulting spongy mass of carbon-rich material first became peat. Then, by action of the heat and pressure of geological forces, peat eventually hardened into coal.

During this process, the plants carbon content was trapped in coal together with the Sun's energy used in the photosynthesis of plants and accumulated over millions of years. This energy source was buried until modern man dug it up and made use of it. It is only very recently on the Earth's time scale that mankind has started to use coal. Historically, the use of coal began when the Romans invaded Britain. While it was used occasionally for heating purposes, the main use of this "black stone" was to make jewelry, since it could be easily carved and polished. It was only during the late 12th century that coal re-emerged as a fuel along the Tyne river in Britain, especially around the rich coal fields of Newcastle. The widespread use of coal however, would not be significant before the middle of the 16th century. At that time, England's population - and that of London especially - was growing rapidly. And, as the city was growing, the nearby land was deforested such that the wood had to be hauled from increasingly distant locations. Wood was used not only for home heating and cooking purposes but also in most industries, such as breweries, iron smelters and in ship building. As the shortage of wood became increasingly pronounced, its price increased such that the poorest of the population were increasingly unable to afford it. These were particularly hard times because Europe had just entered into a so-called "little ice age" which would last until the 18th century. However, a severe energy crisis never materialized thanks to coal, which became increasingly the country's main source of fuel by the beginning of the 17th century. This was not without problems; coal's thick smoke upon burning, made London's air one of the poorest in all of Europe. On some days, the Sun was hardly able to penetrate the coal smoke, and travelers could smell the city miles before they actually saw it.

What really brought about the power of coal as an energy source came along in the early 18th century with the invention of the steam engine. The steam engine was at the heart of the resulting industrial revolution, and it was fueled by coal. At the time, one of the main problems facing coal mining was water seepage and flooding from various sources. Rainwater seeping down from the surface accumulated in the tunnels, and once the mines reached below the water table the surrounding groundwater also contributed to the problem. Consequently, the

Georgius Agricola Metallica

A—axles. B—Wheel which is turned by treading. C—Toothed wheel. D Dkl'm hade or bundles. E—Drum to which are fixed iron clamf-s. F- Second wheel. G—Balls.

Figure 2.1 Water removal in mines during the middle ages. From an engraving by Georgius Agricola-De Re Metallica: book 6 ill. 36, 1556.

A—axles. B—Wheel which is turned by treading. C—Toothed wheel. D Dkl'm hade or bundles. E—Drum to which are fixed iron clamf-s. F- Second wheel. G—Balls.

Figure 2.1 Water removal in mines during the middle ages. From an engraving by Georgius Agricola-De Re Metallica: book 6 ill. 36, 1556.

mines became slowly submerged in water. If the mine was located on a hill, simple draining shafts could be used, but as the mines were pushed deeper into Earth, the water had to be removed by other means. The earliest method relayed on miners hauling the water up in buckets strapped to their backs. This was not really convenient, so various ways were designed to increase the effectiveness of the human labor. Among these were chains of buckets or primitive forms of pumps powered not only by human muscle but also in some cases by windmills, waterwheels (Fig. 2.1), or horse power. However, none of these was very economical or suitable.

One of the most pressing challenges for contemporary England was to find a way to keep its coal mines dry. This led eventually to the introduction of a device invented by Thomas Newcomen, who was not a scholar but a very inventive small-town ironmonger. His device consisted of a piston which moved up by steam generated by heating water with burning coal, and down by reduced pressure resulting from the condensation of steam with cold water. The piston was connected to the rod of a pump used to pump water.

In 1712, one of these Newcomen engines was first used in a coal mine and became an almost immediate hit among mine operators, largely because it was much cheaper to operate than horses and could pump water from a much greater depth than ever before. The drawback was that the engine needed large amounts of coal to generate the steam necessary to keep it going, and therefore found little use outside of the coal mines.

At about this time, James Watt, a carpenters son from Scotland, improved New-comen's steam engine dramatically. Watt realized that as steam was injected and then cooled with water, heat was wasted in the constant reheating and cooling of the cylinder. The installation of a separate condenser immersed in cold water connected to the cylinder kept it hot and avoided unnecessary heat losses (Fig. 2.2). This improved the efficiency of the steam engine by at least a factor of four, and allowed it to move out from the coal mines and find its place in factories.

To really move the industrial revolution ahead, however, another technologic advance was needed: the manufacture of iron using coal-based coke. Until that time, the iron needed to build engines and factories was essentially made using charcoal obtained by burning huge amounts of wood, which was increasingly becoming scarces in Britain. Charcoal provided both the heat and the carbon needed for the reduction of the iron ore. The use of coal to smelt iron was hindered by the impurities it contained, which made it unsuitable. After more than a century of experimentation, however, the key to making iron using coal was found. In the same way that wood was turned into charcoal, coal had first to be baked to drive off the volatiles and form coke. By the 1770s, the technology had advanced to the point where coke could be used in all stages of iron production. With this breakthrough, Britain - rather than being dependent upon iron imports - became, in just a few years, the most efficient iron producer in the world. This allowed it to build its powerful industries at home and its vast empire abroad.

The "coal economy" resulted in a concentration of the ever-larger and mechanized factories, as well as their workforces, into urban areas, making them more

Figure 2.2 Watt's engine, 1774.

Industrial Revolution Locomotive

efficient. The epicenter of this industrial revolution was Manchester, which became the premier center of manufacture in England. The city also became home of the first steam locomotive-driven public railway, the Liverpool and Manchester railway, which opened in 1830 (Fig. 2.3). The "father of the railways" was George Stephenson, who first envisioned moving large quantities of coal over land. It was through the steam locomotive that this became possible, although this invention would in time have revolutionary consequences far beyond the coal industry.

The Liverpool and Manchester Railway became a huge success, transporting hundreds of thousands of passengers during the first months of operation.

This established a bright future for railway as a transportation system and triggered massive investment in this industry. Although other European nations followed its example, Britain had a good 50 years head start in industrialization, and maintained its lead for most of the 19th century. In 1830, Britain produced 80% of the world's coal and, in 1848, more than half of the iron of the world, making the nation the most powerful on Earth until the end of the 19th century. Across the Atlantic, however, the United States - having even more coal and other resources than England - also began to undergo an even faster industrial transformation.

Historically, coal has probably been the most important fossil fuel as it triggered the industrial revolution that led to our present-day modern industrial society. During the 20th century, coal has been supplemented and displaced progressively by oil and natural gas, as well as nuclear power, for electricity generation. Coal was increasingly considered as a "dirty fuel" of the past, and was deemed to have a limited future. Only with the energy crisis in the 1970s and the growing concerns about the safety of nuclear energy, did coal again become an attractive energy source especially for electricity production. Because the reserves of coal are geographically widespread and coal is a heavy and bulky solid which is costly to transport, it is mainly utilized close to its source. The economically recoverable proven coal reserves are enormous, and estimated as being close to one trillion tonnes [2, 3] - enough at current rates of consumption to supply our needs for more than 170 years. This Reserve over Production (R/P) ratio is about three times as large as the one for natural gas, and more than four times as high as that for oil. Unlike oil and natural gas, our coal resources should last at least for the next two centuries. The total coal resources are estimated to be more than 6.2 trillion tonnes [4]. The main reason why the R/P ratio for coal is not even higher is the limited incentive to find new exploitable reserves, given the size of already-known reserves. Production has increased ten-fold over the past 100 years, without any significant increase in coal price. In contrast, the implementation of advanced mining technologies has improved, and will continue to improve productivity and steadily lower the cost of coal extraction and treatment. Higher efficiency in coal transportation, which can represent as much as 50% of the import cost into Europe or Japan, are also improving [5]. Furthermore large reserves, coupled with competition between coal-producing countries, makes a sustained price increase unlikely and should result in relatively flat coal prices in the foreseeable future. In the case of coal, neither the abundant resources nor the competitive prices are determining factors in the fuel's future. The rate of extraction of coal is presently only a function of its relative limited demand. In industrialized countries, where coal is used mainly to generate electricity, the demand will be governed by the ability of coal to compete with natural gas, not only from an economic point of view but also increasingly from environmental considerations. One of the reasons why we no longer rely heavily on coal is that, from an environmental aspect, it is the most polluting fossil fuels in comparison to oil and gas. It usually emits significant levels of pollutants, especially sulfur dioxide, nitrogen oxides, and particulates. Heavy metals such as mercury, lead, arsenic or even uranium are difficult to remove from coal, and are generally re leased into the air upon combustion. In a continuous effort to diminish the environmental impact of coal burning, the development and progressive introduction of new separation technologies applied to existing or new power plants can greatly reduce or nearly eliminate the emissions of SO2, NOx and particulates. Emission regulations for mercury and other impurities present in coal are under evaluation in several nations, including the United States. However, at the present time there are no CO2 emission capture technologies operating in a large-scale power plants. Given the growing concerns about global warming, coal-burning power plants face a major challenge. Compared to oil and gas, coal is the fuel that produces the most CO2 per unit of energy released. To tackle this problem, so-called "clean coal technologies" are being developed to improve the thermal efficiency and reduce emissions and, consequently, the environmental impact of coal-fired power plants [4,6]. Among these technologies, some are already commercially available.

In the Atmospheric Fluidized Bed Combustion (AFBC process), coal is burned in a fluidized bed at atmospheric pressure and the heat recovered to power steam turbines. An improved version of that system, Pressurized Fluidized Bed Combustion (PFBC), in which gas produced by the combustion of coal is used to drive directly a gas turbine, is currently under development. Supercritical and ultra-Supercritical power plants operate under supercritical conditions at steam pressure above 22.1 MPa and 566 °C, where there is no longer any distinction between the gas and liquid phases of water as they form a homogeneous fluid. Such plants are well established and operate routinely at pressures up to 30 MPa with efficiencies above 45%. The introduction of special metal alloys that are more resistant to corrosion (but also are more expensive) to increase the operation pressure to 35 MPa and the thermal efficiency of power generation to over 50% are under development.

Integrated Coal Gasification Combined Cycle (IGCC) is an other emerging technology that has been demonstrated on a commercial scale, but not yet widely deployed. In this case, the coal is first gasified to produce syn-gas, which is then combusted under high pressure in a gas turbine to generate electricity. The hot exhaust gas from this turbine is used to generate steam that can produce additional electricity using a steam turbine. The goal, for the United States using this technology, is to reach a 52% efficiency by 2010. Nevertheless, even with this level of efficiency, an IGCC plant would still produce twice as much CO2 per kWh generated than a combined cycle natural gas turbine [5], the current favored option for power generation. However, the process has also a longer-term strategic importance because it is the first electric power-generating technology to rely on gasified coal. It could therefore act as a bridge to more advanced coal gas-based power plants such as the ambitious "FutureGen", a $1 billion dollar project initiated by the U.S. Department of Energy to develop an economically viable plant which would have zero emissions [7,8]. Beside electricity, this plant would also produce hydrogen from the syn-gas generated during coal gasification, whereas CO2 would be captured and sequestered underground (see also Chapter 12, the use of CO2 and H2 in producing methanol).

From an energy perspective, coal has a major advantage as its resources are still vast and are widely distributed around the world. Furthermore, the outlook for coal supply and prices are subject to less fluctuation than are those for oil and gas. However, coal could be penalized for its high carbon content, and the key uncertainty affecting the future of coal is the impact of environmental policies. Longer-term prospects for coal may therefore depend on the development and introduction of clean coal technologies that would reduce or even eliminate carbon emissions. In any case, coal resources will not last for more than two or three centuries - longer than oil and gas, but still a short period on the time scale of humanity.

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  • efrem
    Who invaded Britain for coal?
    8 years ago

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