# Does running a POP calciner on more shifts cut energy per tonne?

Canonical: https://senseible.earth/answers/bikaner-pop-calciner-energy-by-shift

Yes. TERI measured Bikaner calciners at 472 kcal per kg of plaster on one shift, 438 on two and 403 on three: 1.98, 1.84 and 1.69 GJ per tonne. Firing round the clock uses about 15% less per tonne, because a furnace kept hot loses less heat than one restarted each day.

## Three real units side by side

- 3,600 t a year: 95,000 kWh and 216 t of petcoke, 170 toe. About 60 kg of petcoke per tonne of plaster.
- 6,000 t a year: 175,000 kWh and 330 t of petcoke, 263 toe. About 55 kg.
- 7,800 t a year: 250,000 kWh and 390 t of petcoke, 314 toe. About 50 kg.
- Worked through, these are 1.98, 1.84 and 1.69 GJ per tonne: the one, two and three shift rates. TERI's text calls the 7,800 t unit a two shift plant with a larger drum, but its figures match the three shift rate.

## Why the third shift pays

Each batch takes about 1½ hours in a 1 or 2 t drum. A cold start needs a pilot flame, and every stop lets the furnace walls, built from plain red brick, cool and soak up heat again. Of the 75 working units, 65 already run three shifts; 10 run one shift on a 1 t drum.

## Before you add a shift

- Only add one if you can sell the plaster; idle hot running wastes fuel too.
- Insulate first. Uninsulated walls lose heat on every shift.
- Fix feeding. Petcoke goes in at a fixed rate while air is set by hand, so unburnt fuel clogs the burner orifices and shows as black smoke.
- Log petcoke per batch for a month at your current pattern, then again after the change, so the saving is measured rather than assumed.

## CO2 per tonne of plaster, by unit (estimate)

- 3,600 t: 216 t petcoke x 3.17 = 685 t, plus 95,000 kWh x 0.675 = 64 t: 749 t, or 208 kg per tonne
- 6,000 t: 330 x 3.17 = 1,046 t, plus 118 t: 1,164 t, or 194 kg per tonne
- 7,800 t: 390 x 3.17 = 1,236 t, plus 169 t: 1,405 t, or 180 kg per tonne
- Making 3,600 t at the three shift rate instead: about 28 kg less per tonne, roughly 100 t CO2 a year

Unit energy from TERI's Bikaner plaster of Paris profile. Petcoke at 3.17 t CO2 per tonne from the IPCC 2006 default (32.5 GJ per tonne, 97.5 kg CO2 per GJ); grid factor CEA FY 2025-26.

## What Senseible does here

The calculators turn a month's kWh into CO2 at the CEA grid factor; petcoke has no factor in Senseible, so add it from the IPCC default shown here to compare one shift pattern with another.

- [Carbon calculators](https://senseible.earth/calculators)
- [Bikaner plaster of Paris cluster](https://senseible.earth/answers/bikaner-plaster-of-paris-cluster-petcoke)
- [Plaster of Paris CO2 per tonne](https://senseible.earth/answers/plaster-of-paris-calcination-co2-per-tonne)

Sources: [TERI, Cluster profile: Bikaner plaster of Paris industries (SAMEEEKSHA)](https://sameeeksha.org/pdf/clusterprofile/Bikaner-POP-Industries-Rajasthan.pdf), [IPCC 2006 Guidelines, Volume 2 Energy](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html), [CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en)

Last reviewed 2026-10-31.