The prehistoric forest that became the world's most powerful fuel
Millions of years before the first steam engine, massive tropical wetlands were quietly transforming into the carbon-rich energy that would eventually drive the Industrial Revolution. This wasn't just a geological accident; it was a biological stalemate between evolving plants and the fungi that couldn't yet eat them.
The vast coal deposits we mine today originated during the late Carboniferous and early Permian periods. At this time, Earth's tropical regions were covered in immense 'coal forests.' A fascinating biological bottleneck played a key role: around 360 million years ago, plants evolved lignin, a complex polymer that allowed for the development of the first sturdy trees. However, the fungi and bacteria capable of decomposing this tough material did not evolve the necessary enzymes until roughly 3/4 of a billion years later. This delay allowed massive amounts of dead plant matter to accumulate in oxygen-poor wetlands, eventually turning into peat.
The transformation from organic matter to rock, known as coalification, is driven primarily by temperature rather than just time or pressure. As layers of sediment buried these peat bogs, heat and pressure triggered chemical processes like dehydration, decarboxylation, and demethanation. These reactions stripped away water, oxygen, and hydrogen, steadily increasing the proportion of carbon. This process creates a spectrum of coal ranks: from the relatively mild lignite (brown coal) to the high-temperature, high-pressure anthracite, which is so dense it can fracture like thick glass.
While coal was used for millennia—with evidence of its use in China as early as 1000 BC and in Roman Britain by the second century AD—its true impact was unlocked by the steam engine. Today, coal remains a central, albeit controversial, pillar of global energy. In 2024, coal-related CO2 emissions exceeded 15 billion tonnes, accounting for more than a quarter of all global greenhouse gases. As the world seeks to meet the Paris Agreement targets, the industry faces a massive transition, with a projected need to halve coal use between 2020 and 2030.
Source: Coal
