Low-sulphur coal produces less sulphur dioxide (SO2) when it burns. That makes it easier for power plants, cement kilns and industrial boilers to meet emission limits, reduces corrosion in boilers and chimneys, and lowers the cost of running flue gas scrubbers. For many plants, choosing low-sulphur coal is the simplest and cheapest way to cut SO2.
Coal is usually described as low-sulphur when its total sulphur is below about 1%, and many export coals are well below that.
Why sulphur matters
When coal burns, the sulphur in it forms SO2. SO2 causes acid rain and respiratory problems, so most countries limit how much a plant may emit. Plants can meet those limits in two ways: burn coal with less sulphur, or remove SO2 from the flue gas with a scrubber. Most use a combination.
The benefits of low-sulphur coal
1. Lower emissions
Less sulphur in the coal means less SO2 formed. For plants without scrubbers, coal sulphur content can decide whether they meet their permit at all.
2. Lower scrubber costs
For plants with flue gas desulphurisation, lower sulphur means less limestone used, less gypsum or waste produced and lower running costs.
3. Less corrosion
Sulphur compounds condense as acids in cooler parts of the boiler, air heater and chimney. Lower sulphur reduces corrosion and maintenance.
4. Better product quality
In cement kilns, sulphur affects clinker chemistry and can cause build-ups. In steelmaking, sulphur in coke passes into the iron and must be removed. Low sulphur helps both.
5. Easier permits and reporting
Plants burning low-sulphur coal often have more headroom in their emission permits and an easier compliance record.
Where low-sulphur coal comes from
| Origin | Typical sulphur profile |
|---|---|
| Indonesia | Many export coals are very low in sulphur and ash |
| Australia | Generally low to moderate sulphur |
| Colombia | Generally low sulphur |
| Russia and South Africa | Varies by mine |
See Indonesian coal and top coal exporting countries.
Trade-offs to consider
Low-sulphur coal is not automatically the best choice. Many low-sulphur Indonesian coals also have higher moisture and lower calorific value, so a plant must burn more tonnes for the same energy. Compare coals on delivered cost per unit of energy and check that the coal suits your boiler. See how to assess coal quality.
How to specify sulphur in a contract
- State total sulphur and its basis, such as air-dried or as received
- Set a typical value and a rejection limit
- Consider a price adjustment for sulphur above the typical value
- Require independent analysis at loading
Buying low-sulphur Indonesian coal through Agromer
Agromer holds mandates for Indonesian thermal coal for power plants and industrial buyers. Send us your specification, including your sulphur limit, monthly quantity, contract length and discharge port. We work with an end-buyer LOI, payment by 100% DLC or SBLC, and SGS inspection at loading. See our Indonesian coal supply page.
Frequently asked questions
What is low-sulphur coal?
Coal with low total sulphur content, usually below about 1%. Many export coals are much lower.
Why is low-sulphur coal better?
It produces less SO2, which reduces pollution, eases compliance and lowers corrosion and scrubber costs.
Is Indonesian coal low in sulphur?
Most Indonesian export coal is low in sulphur and ash.
Does low-sulphur coal cost more?
Sometimes. Price depends mostly on calorific value, but low sulphur can carry a premium where emission limits are strict.
Do plants with scrubbers need low-sulphur coal?
Not necessarily, but lower sulphur still reduces scrubber running costs and corrosion.
How is coal sulphur measured?
By laboratory analysis of samples taken during loading, reported as total sulphur on a stated basis.