How is coal formed?
Coal is a non-renewable energy source that can be burned for fuel and is used to generate electricity. Burning it adds a huge amount of carbon dioxide to the atmosphere and it’s the single biggest contributor to human-made climate change. Under current plans, the UK aims to phase-out unabated coal-fired power stations by 2025.
1. DECAYING ORGANIC MATTER CREATES PEAT
Around 300 million years ago, in the Carboniferous, plant matter from the dense, swampy forests accumulated and lay decaying in the bottom of the swamps. Burial and compaction under anaerobic conditions formed peat from this partially decomposed organic matter.
2. PEAT BECOMES LIGNITE
When this peat was buried at relatively shallow depths, continued heat and pressure compressed the peat between layers of sediment into lignite: a soft, brownish-black coal-like material with a high moisture content.
3. LIGNITE BECOMES COAL
With continued burial, heat and structural deformation, this lignite metamorphoses into sub-bituminous and bituminous coal, and then to anthracite (hard coal). The more metamorphism, the harder and more carbon-rich the coal becomes.
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