Two ways to count the same heat
Gross calorific value (GCV, also higher heating value) counts all the heat released when coal burns, including the heat recovered when water vapour in the flue gas condenses. Net calorific value (NCV, or lower heating value) excludes that condensation heat — because in most real furnaces the flue gas leaves hot and that energy is never recovered.
So NCV is always lower than GCV for the same coal. The gap is the energy tied up in vaporising moisture and the water formed from hydrogen in the fuel.
Why the gap matters
NCV is closer to the heat your boiler actually delivers, while GCV is the figure coal is most often priced and traded on in India. Problems arise only when the two are mixed up — comparing a GCV quote against an NCV quote makes one look cheaper than it is.
What to do
Always confirm whether a quoted calorific value is GCV or NCV, and on what moisture basis (ARB/ADB). Compare like with like, and ask for a documented certificate for the consignment you are buying.
Frequently asked
- What is the difference between GCV and NCV?
- GCV (gross calorific value) counts all heat released, including the heat from condensing water vapour; NCV (net calorific value) excludes that, so it is always lower. NCV is closer to usable boiler heat; GCV is the common trading basis in India.
- Is coal priced on GCV or NCV in India?
- Domestic thermal coal in India is most commonly traded and priced on GCV. Always confirm the basis on a quote and compare like with like.