At Surat prices, is lignite or imported coal cheaper per unit of heat?

At the Bureau of Energy Efficiency (BEE) Surat manual's prices, lignite is rupees (Rs) 2,500 to 2,800 a tonne and imported coal Rs 3,500 to 3,800. Per million kilocalories (kcal), with lignite at 4,000 kcal a kilogram (kg), coal at 6,000 is cheaper per heat and coal at 4,500 is dearer. The reports and manual disagree on coal's value.

The printed inputs

• Cluster manual, fuel price table: lignite Rs 2,500 to 2,800 a tonne, imported coal Rs 3,500 to 3,800.
• Heating values: imported coal 5,800 kcal a kg in the manual's cases and 6,000 in the 3 tonnes an hour (TPH) boiler report, which also prints 4,500 for coal in the new boiler's specification. The manual's cluster table implies 4,100. Lignite 4,000 in the 4 TPH boiler report.
• The two boiler reports print their own prices: coal Rs 3,800 a tonne, lignite Rs 2,830.

Rupees per million kcal

Cost per million kcal is Rs per tonne divided by the heating value in kcal a kg over 1,000. Coal at 3,500 to 3,800: Rs 583 to 633 at 6,000, or Rs 603 to 655 at 5,800. Lignite at 2,500 to 2,800 and 4,000: Rs 625 to 700. The ranges overlap, so the manual's price table alone does not rank them.

At the two reports' own prices the order holds only at 6,000 kcal a kg for coal: coal 3,800 / 6.0 = Rs 633, lignite 2,830 / 4.0 = Rs 708. Lignite is 25% cheaper a tonne and 12% dearer per unit of heat. At the 4,500 the reports print for the new boiler's coal, coal is 3,800 / 4.5 = Rs 844 and lignite at Rs 708 is about 16% cheaper per unit of heat, so the order flips. The reports and the manual do not agree on coal's heating value, so test your own coal before ranking.

What the rupees do not include

• Boiler efficiency. The reports measured old boilers at 31 to 47%, so much of either fuel's heat never reaches the steam.
• Handling: a lower-heat fuel means more tonnes carried and stored for the same steam.
• Delivered price on your invoice. The manual's condensate case uses coal at Rs 3,350 a tonne, below its own price table.
• Carbon dioxide (CO2). Each fuel has its own factor per tonne; use your supplier's test report. Price per heat does not give CO2 per heat.

Do it on your invoices

1. Take the last three invoices for each fuel: rupees per tonne delivered.
2. Take the heating value from each test report.
3. Divide as above and compare rupees per million kcal, then multiply by the efficiency each fuel actually gives in your boiler.

The two reports' prices

• Coal: Rs 3,800 a tonne / 6.0 million kcal a tonne = Rs 633 per million kcal
• Lignite: Rs 2,830 / 4.0 = Rs 708 per million kcal
• Coal at 4,500 kcal a kg instead: 3,800 / 4.5 = Rs 844 per million kcal; lignite is 1 minus 708 / 844 = about 16% cheaper
• Lignite against coal per tonne: 1 minus 2,830 / 3,800 = 25.5% cheaper; per heat: 708 / 633 = about 12% dearer
• Heat in a kilogram: lignite 4,000 / coal 6,000 = 67%

Prices and heating values are the reports' own, at their year's prices. The comparison is our arithmetic, so check today's invoices.

What Senseible does here

Senseible reads fuel invoices into monthly records, and takes a coal heating value only when the bill prints one. A lignite or test-report heating value is yours to keep.

• Surat 3 and 4 tonne boiler reports
• Surat coal heating value in the manual
• Green loan readiness check

Sources: BEE, Manual on Energy Conservation Measures in Textile Cluster, Surat (SAMEEEKSHA), BEE, Detailed project report: energy efficient boiler, 3 TPH, Surat (SAMEEEKSHA), BEE, Detailed project report: energy efficient boiler, 4 TPH, Surat (SAMEEEKSHA)

Last reviewed 2026-11-06. Prices are at BEE's report years. Re-run with today's delivered prices and your own test reports.