Converting Coal Plants to Natural Gas - by Brian Potter

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Converting Coal Plants to Natural Gas<br>Brian Potter<br>Jun 19, 2026

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For the better part of the last several hundred years, coal was the fuel of choice for generating power. Burning coal powered Thomas Newcomen’s steam engine, invented in Britain in the early 18th century, and the first of a line of increasingly efficient converters of coal to usable energy. The Newcomen engine was in fact so inefficient and consumed so much coal that it was almost exclusively used at coal mines, where fuel could be obtained cheaply. The improved steam engines that followed over the 18th and 19th centuries — Watt’s rotative engine, high-pressure Cornish engines, triple-expansion engines, Parsons’ steam turbine — were likewise fired by coal. By the early 20th century, Britain was burning 52 million tons of coal a year to provide power for factories and mines.<br>The rise of the gas-powered automobile in the early 20th century shifted a substantial portion of coal consumption to petroleum, but coal still remained favored for industrial power. And this didn’t change with the emergence of the electric power grid: Thomas Edison’s first central electricity generating station at Pearl Street in New York used coal-fired reciprocating engines, and coal was the primary method of generating electric power in the US well into the 21st century.<br>By the end of the 20th century, however, this trend was starting to shift. For most of the 20th century coal made up around 50% of US electricity generation, but after peaking at around 57% of electricity generation in the mid-1980s, coal started to decline as a share of electricity generation in the US. And starting around 2008, coal-generated electricity began to decline in absolute terms, falling from over 1.6 trillion kilowatt-hours produced in 2009 to around 0.8 trillion in 2020. Today, coal supplies around 16% of US electricity, a share that seems likely to continue to fall long-term.

As coal became less popular, many coal plants — over 200 since 2008 — have simply shut down.1 But some of these plants were instead converted to burn natural gas in place of coal. Since 2008 there have been around 140 such conversions.

Given recent attempts to reinvigorate the coal industry, with the Trump Administration forcing plants to stay online and trying to fund the construction of new coal plants, it’s worth understanding what drove so many plant operators to cease burning coal and switch to natural gas.<br>Drivers of coal-to-gas conversion

The spate of coal-to-gas conversions that began around 2008 was the product of two factors.<br>The first was regulatory. Burning coal emits a great deal of harmful pollutants (such as mercury), and over time regulation of these emissions has become stricter. In 2000 the Environmental Protection Agency (EPA) decided to develop regulations for the emission of mercury, and while this was temporarily delayed by the Bush Administration, by 2008 it was clear that stricter coal plant emissions would be a reality. In 2011, the EPA proposed a new set of coal plant emissions restrictions, the Mercury and Air Toxics Standards (MATS), which dramatically reduced the amount of mercury, toxic metals, and acid gases that coal and oil plants were allowed to emit. MATS, however, didn’t apply to natural gas plants, as gas burns much more cleanly and produces dramatically less harmful particulate emissions.<br>Alongside this new, more stringent regulation, the US shale gas boom made natural gas an increasingly attractive fuel for generating power. Between the late 1980s and 2011, natural gas went from 10% to nearly 30% of US electricity generation. And while the price of gas had risen through the early 2000s, it began to fall steeply in 2008. What’s more, it was projected to stay cheap for the foreseeable future.

Faced with increasingly strict environmental regulation and the rise of widely available and affordable natural gas, coal plant owners were faced with several options. One was to simply shut down their plants. Another was to install the required equipment to reduce emissions enough to comply with MATS regulations. This equipment was expensive to install and acted as a drag on plant efficiency, since it took energy to operate, but it was nevertheless often worth it. Today there are 219 operating coal plants in the US, all of which are in compliance with the original MATS regulations.<br>But some plant operators, instead of installing the required emissions equipment to comply with MATS, opted to convert the plants to burn natural gas. Converted plants were generally older, smaller-capacity plants that were relatively inefficient, used to provide extra capacity when needed rather than supplying baseload power.<br>Converting coal plants to burn natural gas wasn’t a new idea — the idea first began to be discussed in the 1980s, and during the 1990s and 2000s a few plants were converted — but the shale boom...