Coal — mine, train, plant and ash

The most solid and visible fossil cycle, from the seam to the ash landfill.

Black electricity starts in a mountain or underground

Two forms of extraction, two very different risk landscapes

Coal is extracted in two fundamentally different ways, and each distributes its cost differently. In open-pit mines, entire layers of soil and rock — what the industry calls "overburden" — are removed with excavators, mechanical shovels and large-tonnage haul trucks until the coal seam is exposed; the landscape is transformed on a large scale, though the direct risk to workers is lower than in underground mining. In underground mines, galleries are dug following the seam, requiring constant ventilation to prevent the build-up of firedamp — an explosive mix of methane and air —, continuous pumping to control water ingress, and permanent safety monitoring against the risk of collapse. Both routes then require washing and sorting the coal to reduce impurities, and transporting it by conveyor belt, rail or ship, sometimes thousands of kilometers to the plant where it will be burned.

What happens in the boiler, beyond CO₂

Burning coal heats water to produce steam and turn a turbine — the same mechanical principle as any thermal plant. But besides carbon dioxide, combustion releases a set of pollutants most people do not directly associate with "climate change" but that carry an immediate, measurable health cost: fine particles that penetrate the lungs, sulfur and nitrogen oxides that contribute to acid rain and urban smog, and heavy metals — including mercury — naturally present in the ore and released on combustion. Electrostatic filters and desulphurization systems remove much of these pollutants before they leave the chimney, but they do not eliminate the problem: they convert it into industrial gypsum, sludge and ash that have to be managed on land, in turn consuming materials, water and additional energy.

The mountain of ash left after burning

A medium-sized coal plant can generate, every year, several hundred thousand tonnes of ash and other combustion residues — a volume, year after year, far larger than the entire accumulated history of used nuclear fuel worldwide (a comparison developed with concrete figures in this section's nuclear waste leaf). That ash can be deposited in ponds or dedicated landfills, and if those deposits are not properly sealed or maintained, they can leach heavy metals into groundwater for years after the plant has stopped operating.

What remains underground when the mine closes

A coal mine, especially if underground, can keep draining acidic water — the result of water reacting with sulphurous minerals exposed by excavation — for decades after closure, and can keep passively releasing methane trapped in the surrounding rock layers. Restoring an open-pit mine's land — recovering topography, fertile soil and vegetation — can take longer than the mine's own operating life, and its cost is rarely fully reflected in coal's sale price while the mine was active.

The cost that never shows up in the sack of coal

Coal's market price has never fully included the respiratory and cardiovascular illness associated with air pollution, methane emissions from the mining itself, the water consumed, long-term ash management, or final land restoration. Replacing coal with almost any other electricity source — including natural gas, with all its own limitations — usually offers one of the largest and fastest available reductions in health and climate impact for any electrical system. But a serious transition cannot simply close mines and plants: it must also support the workers and entire regions whose economy depended on coal for generations, and who did not individually choose the global climate problem they are now being asked to give up for.

The only advantage left is the infrastructure already built

In favor: storable, transportable fuel and mature industrial infrastructure in many countries; it still provides baseload electricity in regions where replacing it takes time, money and a grid ready for other sources.

Against, structurally: coal tops almost every comparative energy table — more CO₂ per unit generated than any other conventional source, the highest mortality from air pollution, mines that leave acidic water and land that takes years to restore. No filter or capture technology changes that balance cheaply at scale yet.

What cannot be ignored when closing a plant or a mine: the workers and regions that depended on coal for generations did not choose the global climate problem. A just transition requires worker retraining, regional investment and realistic timelines, not just a sudden closure that shifts the social cost onto those least responsible for it.

The useful question is not "coal, yes or no?" — the climate and health evidence is unanimous — but "what replaces the generation and the jobs, on what timeline, and who pays for the transition of the people who lived off the mine or the plant?"

The numbers, with their source

The truck nobody sees on their electricity bill

A large-tonnage mine haul truck (the "ultra-class" type, capable of carrying 300-400 tonnes) can consume between 300 and 500 liters of diesel per hour in continuous operation; over a year, a single truck of this kind burns on the order of 900,000 liters of fuel. In a large mine, these vehicles account for between 30% and 50% of the entire operation's energy consumption. Worldwide, the fleet of mine haul trucks emits on the order of 68 million tonnes of CO₂ per year — before a single kilo of coal has been burned in a power plant.

Source: RMI — Pulling the Weight of Heavy Truck Decarbonization.

Why "liters per hour" is not the right question

Converting an engine's power or its hourly consumption into an environmental judgment is a scale error: what matters is how much energy and how many emissions it takes per tonne of coal actually usable, not per tonne of rock moved. That figure depends on the ore grade (how much usable coal exists per tonne of extracted material), depth, haul distance, and whether the mine is open-pit or underground — which is why a serious audit asks for annual fuel and electricity use, tonnes moved and tonnes of product, not just the machinery's spec sheet.

The comparative table

What this table is missing

These figures describe electricity generation; they do not include the cost of restoring an open-pit mine once exhausted, sealing underground galleries to prevent acid drainage, or managing for decades the ash and scrubber sludge left by each plant — costs that almost never show up in the price of coal-generated electricity while the plant is still operating.

Sources

• The IEA maintains a full profile of coal as an energy source.
• The WHO documents the health effects of air pollution.
• NREL harmonizes coal's life-cycle emissions against other sources: Life Cycle Assessment Harmonization.
• Data on mine-truck fuel consumption and emissions: RMI — Pulling the Weight of Heavy Truck Decarbonization.