When society began embracing coal as a source of fuel, it brought benefits of efficiency to industry and manufacturing alongside problems in environmental effects and safety concerns. As science and technology progressed, these methods were refined to address safety concerns. Looking at the coal gasification process as a story that has both positives and negatives can show the true nature of how it happened.
History of Coal Gasification
Though scientists had studied the process of emitting gas from burning coal since 1780, it would take until the early 1900s when the processes would become commercialized for use across industries in cities worldwide.
Converting coal to gas in the coal gasification process dates back to 19th-century England. During these decades, coal miners used processes that crushed coal in the presence of oxygen and steam at high temperatures to produce gas.
By the 1860s, the United States had risen as an industrial giant thanks to large-scale coal mining processes across the Appalachian Mountains, the Midwestern prairies and even the Cascades and Rockies.
Disadvantages and Advantages of Coal
The nation stood as the largest producer of coal in the world, but history also remembers a darker side to the story. Steam shovels, tractors and equipment used in coal mining eroded the soil while railroads, industrial plants and homes polluted cities across the country.
Poorer communities relied on cheaper, dirtier coal that they directly used while the elite class of wealthy families would profit off the benefits of gas and electricity, increasing the divide between the poor and the rich. The working class flooded factories with unskilled workers in dangerous work conditions resulting in, by the 20th century, tens of thousands of people died each year on railroads, in factories and in coal mines themselves.
The industrial sector that had profited over such an effective way to harness the energy of the earth showed these troublesome disadvantages alongside advantages of the coal industry. When scientists and engineers came up with methods to produce coal gas for industrial and economic purposes, this would later progress to more effective techniques such as oil and synthetic natural gas production.
As people understood the benefits and advantages of coal gasification, they created these innovations to suit their needs. This took the form of larger plants and the discoveries of more coal reservoirs in the earth. Scaling up to get to where coal gasification is today wasn't so straightforward, though.
The disadvantages and advantages of the coal gasification prompted responses from concerned citizens and governments through labor activism such as strikes and unionizing. New regulations and institutions, such as how U.S. president Theodore Roosevelt wanted an increase in government supervision over business enterprises, spread across the nation in the early 1900s. Employers stood their ground against the demands of middle-class workers for better work conditions alongside more reasonable working hours and salaries. Industrialization brought progressive reform through these challenges of labor.
Science of Coal Gasification
By the early 20th century, more advances took foot in the Unites States and the United Kingdom. Converting coal to gas using gas solid reactions primarily featured the reaction of the carbon in coal with steam at pressures lower than 10 MPa and temperatures above 750°C.
The coal gasification process would produce hydrogen, ammonia, methanol and hydrocarbons, and they were also used with steam to create synthetic natural gas (SNG). These reactions would produce synthetic gases generally composed of carbon monoxide (CO) and hydrogen gas (H2).
By the 1930s, underground coal gasification (UCG) also took root. UCG in particular used a method of circulating gasification agents like air, oxygen and water into the coal itself. This process converted coal to useful gases from the coal itself without needing to mine the material.
It would take an input of heat to start these endothermic reactions by using a heat source from another process or burning part of the coal itself. The heat given off by the gases could power engines or be used to create chemical products, some of which would be transported to the surface of the Earth from the mines with less start-up capital necessary, lower operating costs and less construction time.
However, practical applications of UCG were and still continue to be constrained by the absence of quantitative knowledge of the chemical process itself. Still, engineers took advantage of cavity size used to contain the coal to maximize heat energy released by understanding the permeability of the cavity material without having the cavity disintegrate itself.
Advances in Coal Gasification
Advances in coal gasification throughout history would ensure that the positives would outweigh the negatives of coal as it would be used across applications. The reforms through political, social and other realms would lead manufacturers to take into account human labor as a capital resource in the economy to prevent costs to human life alongside advances in science and technology.
The advances would come with conflicts such as the 1914 Ludlow Massacre in southern Colorado, in which the Colorado National Guard killed 18 men, women and children while the miners were on strike.
By the 1930s field trials for the best ways to use coal in producing steam were beginning to spread across the planet. The USSR had pioneered technologies by the 1930s, and they soon spread to the UK, Spain, China, Belgium and the US in the coming decades. The feasibility studies that researchers performed sought to take advantage of coal to improve efficiency and effectiveness.
In response to shortages of natural gas by the 1970s and 1980s, researchers experimented with using other gases such as air or carbon dioxide, and this would lead to the use of hydrogen gas alongside high temperatures with a catalyst.
Coal gasification methods also sought to remove impurities like sulfur and mercury from coal to make it a more efficient source of energy. These methods of using energy more efficiently lead to recycling the ash from coal gasification into a concrete aggregate rather than sending it to a landfill.
Combined cycles used the steam generated from coal gasification to power a second generator and operate at 45-50% efficiency, a rate 10-15% higher than traditional manufacturing plants. The combined cycle would decrease carbon dioxide emission and lead to even more economical developments such as separating carbon dioxide from the other gases produced.
Modern Positives and Negatives of Coal
Innovations in the process of coal gasification have sought to make improvements at each step. Determining the appropriate temperature at which a gasifier should operate would lead researchers to monitor the outer shell of gasifier chambers using infrared cameras.
They could, then, analyze temperature using a continuous source of temperature data alongside other factors such as the shape of gasifiers and the materials used. Technology from manufacturer Pepperl+Fuchs currently uses systems of up to 13 cameras in each gasifier to record this.
These advances show how society can weigh the good things and bad things about coal throughout history.
About the Author
S. Hussain Ather is a Master's student in Science Communications the University of California, Santa Cruz. After studying physics and philosophy as an undergraduate at Indiana University-Bloomington, he worked as a scientist at the National Institutes of Health for two years. He primarily performs research in and write about neuroscience and philosophy, however, his interests span ethics, policy, and other areas relevant to science.