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| Fig. 1: Visualizing Utah's Yearly Coal Production. [2,3] (Source: L. Hansen) |
Immense troves of coal sleep under the surface of Utah's sprawling landscape: Coal can be found under about one-fifth of the state, with at least 5.4 billion short tons available to be mined according to the best estimates. [1] This essay will briefly describe the current state of the Utah coal industry, and then make predictions about its trajectory in the upcoming years.
Most of the coal under Utah comes from the Cretaceous age and is bituminous, which refers to a stage in organic material's evolution from plant matter to a denser, harder, more carbon-rich material (a process known as coalification). [1] Bituminous coal appears glassy and smooth. Coal mining contributes significantly to Utah's economy. In 2020, a total of 13.5 million short tons were mined in Utah, the 10nth highest of any state. [2] However, the amount of coal being mined in Utah peaked in 1998, and has been on a steady decline since then (Fig. 1).
In Utah, there are estimated to be between 5.4 and 14 billion short tons of coal that are economically feasible to mine, and technologically possible to do so. [1] It is likely there is more coal, based on reasonable geologic assumptions. This range merely represents the coal that is confirmed to exist. This estimate is dynamic, changing as more strains of coal are discovered and economic conditions fluctuate. However, it is very difficult to predict how the estimate will change, so we will assume that there is between 5.4 and 14 billion tons in the reserves for the purposes of this analysis.
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| Fig. 2: Extrapolating Utah's Coal Production with a Linear Model. [2,3] (Source: L. Hansen) |
How fast will Utah mine this remaining coal? To answer this question, we must predict how much coal will be mined in upcoming years. If we assume that Utah will continue to mine the same amount of coal as was mined in 2020 (13.5 million short tons per year), this reserve will last between approximately 408-1058 years from 2020 (5.5 billion/13.5 million - 14 billion/13.5 million). [2] However the graph depicts a downward trend in the amount of coal being mined in recent years.
If we assume that the amount of coal being mined continues to decrease at the same rate as it has since 1998, we can fit a linear model model to the data. We can see that a linear model fits the recent trends very well (see Fig. 2). This model predicts that no coal will be mined in Utah by 2036, which is well before the reserves would be depleted. If Utah no longer mines coal by then, it would not be due to a lack of coal to mine. However, this result must be taken with a grain of salt: this prediction is based solely on the trends in the amount of coal that has been mined in recent years. There are many other factors that are relevant to such an analysis: the development of alternative energy sources; growing energy needs due to population growth; government intervention; and socio-political events like international conflict. These factors could cause the demand for coal to change in drastic, unexpected ways. Extrapolating recent trends gives some insight into what the future might look like, but a more comprehensive analysis would be needed to make predictions with more confidence.
© Luke Hansen. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "Annual Evaluation Report for the Coal Regulatory Program Administered by the Utah Division of Oil, Gas and Mining," U.S. Department of the Interior, September 2021.
[2] "S. E. Mills et al., "Utah Mining 2021," Utah Geological Survey, Circular 134, 2022.
[3] M. D. Vanden Berg, "Annual Review and Forecast of Utah Coal Production and Distribution - 2009," Utah Geological Survey, Circular 112, 2009.