--- title: Which Fuel Is Used in Thermal Power Plants? url: https://upfuel.online/blog/thermal-power-plant-fuel topic: Transport & Industry author: Priya Raman (Energy science editor) published: 2026-06-16 updated: 2026-08-28 source: UpFuel — https://upfuel.online --- # Which Fuel Is Used in Thermal Power Plants? Most thermal power stations burn pulverised coal, some natural gas or lignite. What happens between the coal wagon and your light switch. ## Summary Mostly coal, ground to a powder as fine as talc and blown into the furnace. Natural gas, lignite, fuel oil and biomass are used in other plants. Whatever the fuel, the job is the same: boil water, spin a turbine, generate electricity. ## Key takeaways - Coal is the dominant fuel, burned as pulverised fuel ground finer than face powder. - Gas-fired plants use combined cycle, reaching around 60% efficiency against coal's 33–40%. - Oil is now mostly a start-up and backup fuel, not a main one. - About two-thirds of the fuel energy leaves as waste heat, not electricity. - Ash handling is a major part of running any coal plant. I once spent an afternoon at a coal plant watching the fuel handling yard, and the thing that stuck with me was not the size of the furnace. It was the mills. Rooms full of machines whose entire job is to grind rock into powder, running constantly, consuming a serious share of the station's own electricity. Nobody outside the industry pictures that when they think about coal power. They picture shovels. ## The short version **Coal** is the main fuel, burned as pulverised fuel. **Natural gas** is second and gaining. **Lignite** is burned near where it is mined, **fuel oil** mostly helps light the furnace, and **biomass** is co-fired in some plants. But the fuel is only the first stage. Every thermal plant is really a water-boiling machine with a fuel choice bolted onto the front. ## Why coal has to be powdered This is the part that surprises people, and it is worth understanding because it explains everything about how a modern boiler behaves. Burning happens at surfaces. A lump of coal exposes very little surface for its mass, so it burns slowly, unevenly and incompletely — which is exactly the problem you get with a solid fuel in a domestic grate, and the same reason [green wood makes such a poor fuel](/blog/green-wood-unfit-as-fuel). Grind the same coal to a powder where roughly 70% passes a 75 micron sieve — finer than face powder — and the surface area becomes enormous. Blown into the furnace suspended in hot air, it burns almost like a gas: fast, near-complete, and controllable within seconds. That control matters more than efficiency in daily operation. The grid demands what it demands, minute to minute, and a furnace you cannot turn down is useless. ## What the different fuels are actually like to run **Bituminous coal** is the workhorse. Energy content around 25,000–33,000 kJ/kg, and in India typically 30–45% ash, which is the operator's real headache. High ash means more fuel handled for the same heat, more wear on the mills, and vastly more ash to get rid of afterwards. **Lignite**, or brown coal, holds so much moisture and so little energy that transporting it rarely makes sense. So lignite stations are built on top of the mine. Neyveli in Tamil Nadu is the classic Indian example. **Natural gas** is the clean, efficient option — and gas plants work quite differently, which is covered below. **Fuel oil and diesel** have mostly retreated to a supporting role. They light the furnace from cold and stabilise the flame at low load, because pulverised coal will not ignite on its own until the furnace is hot. This is a nice illustration of [ignition temperature](/blog/ignition-temperature-explained) in industrial practice: coal's is high enough that you need a more eager fuel to get things going. **Biomass** — rice husk, bagasse, agricultural pellets — is co-fired with coal in a growing number of plants, usually at 5–10%. ## Why gas plants beat coal plants on efficiency A coal plant has one cycle: burn fuel, boil water, spin a steam turbine. Roughly a third of the fuel energy becomes electricity and the rest becomes waste heat. A combined cycle gas plant gets two. Gas burns in a gas turbine, which generates power directly. The exhaust — still around 600 °C, far too hot to simply throw away — passes through a heat recovery boiler to raise steam for a second turbine. Two cycles, one lot of fuel, roughly 60% efficiency. Combine that with gas producing [about half the carbon dioxide of coal](/blog/why-natural-gas-is-called-a-clean-fuel) per unit of energy, and a gas plant emits well under half the CO₂ of a coal plant per unit of electricity. That single comparison is why gas displaced coal so quickly wherever pipelines exist. ## The two-thirds nobody talks about Here is the fact I wish were better known: **most of the fuel burned in a thermal power station never becomes electricity.** At 35% efficiency, roughly 65% of the energy leaves as low-grade heat — mostly through the condenser into river water, sea water or a cooling tower. That is not bad engineering. It is the second law of thermodynamics setting a limit on what any heat engine can do, and it is precisely the limit that [fuel cells escape](/blog/fuel-cells-explained) by skipping the heat stage entirely. It also explains why power stations are always beside water, and why "waste heat" is such a persistent target for district heating schemes. ## If you are trying to picture the whole thing The five stages in the figure above are worth reading in order, because they apply whether the fuel is coal, gas, biomass or nuclear. Change the box at the front and the rest of the plant barely knows the difference — nuclear plants are steam plants too, with a reactor where the furnace would be. ## The compact answer > Thermal power plants mainly use **coal**, burned in the form of pulverised fuel. Some use natural gas, lignite, fuel oil or biomass. The fuel is burned to heat water into high-pressure steam, which drives a turbine coupled to a generator. Coal plants convert about 33–42% of the fuel energy into electricity; combined cycle gas plants reach around 60%. ## FAQ ### Which type of fuel is used in a thermal power plant? Mainly coal, burned as pulverised fuel. Natural gas is the second most common, used in combined cycle plants. Lignite is burned at pithead stations, and fuel oil is now used mostly for starting up and stabilising the flame rather than as a main fuel. ### Why is coal ground into powder before burning? Because surface area decides burning speed. A lump of coal burns slowly from the outside in, but coal ground to a powder finer than face powder has an enormous surface area and burns almost like a gas — fast, completely, and controllably enough to follow demand on the grid. ### Why are gas power stations more efficient than coal ones? Because they get two bites at the fuel. A combined cycle plant burns gas in a gas turbine first, then uses the hot exhaust to raise steam for a second, steam turbine. Two cycles from one lot of fuel takes efficiency to roughly 60%, against 33–42% for a coal plant that only has the steam cycle. ### What happens to the ash from a coal power station? Fly ash is captured from the flue gas by electrostatic precipitators or bag filters, and bottom ash falls to the base of the furnace. Together they can be 30–45% of the mass of Indian coal. Much is used in cement and concrete; the rest goes to ash ponds or landfill, which is one of the more difficult waste streams in power generation. --- Safety note: indoor fuel burning carries carbon monoxide, fire and air-quality risks. Follow your appliance manual and local regulations, fit a certified CO alarm, and use a qualified engineer for installations.