# How different is the energy use of a parboiled rice mill and a hulling-only mill?

Canonical: https://senseible.earth/answers/red-hills-parboiled-vs-hulling-mill-energy

Roughly 25 times. In Red Hills, a medium parboiled mill uses 384 toe a year, mostly husk or wood for steam, plus 545,460 kWh. A hulling unit that only removes husk and polishes uses 180,000 kWh, 15 toe, about 40 kWh per tonne of rice. Soaking, steaming and drying make the gap.

## What each mill does

A Red Hills parboiled mill cleans paddy, soaks it about 4 hours in pits holding about 8 t each, steams it in 600 to 700 kg batches, then dries it from about 32% moisture to 22% and on to 13 to 14% over about 30 hours, before milling. A hulling unit skips soaking, steaming and drying and sends cleaned paddy straight to milling. Hulling units run round the clock for about three months, making raw rice for government programmes.

## The three typical units

- Medium parboiled, 4 tph, 40 units: 545,460 kWh and 384 toe a year; electricity is about 12% of its energy.
- Small parboiled, 3 tph, 30 units: 109,092 kWh and 110 toe a year.
- Hulling, 3 tph, 30 units: 180,000 kWh and 15 toe a year, all electricity; about 40 kWh per tonne of rice, 0.003 toe.
- Parboiled units overall: 0.061 to 0.064 toe per tonne. Milling alone draws 6.5 to 7 kWh per 75 kg bag of paddy.

## The dryer is the big steam user

About 80% of a parboiled mill's steam goes to the dryer, where steam heats air through a heat exchanger. TERI costed a husk fired hot air generator for a medium mill burning 1,120 t of husk, 900 t of it for drying: 28% saved, about 250 t of husk, Rs 5 lakh a year for Rs 5.5 lakh, payback about a year. The boiler can then shrink to about 1 tph, for parboiling only.

## Two cheaper fixes

- Economiser and condensate return: 112 t of husk a year for Rs 1 lakh, payback about 5 months.
- Combustion air control, against the unburnt husk and black smoke many boilers show: 60 t a year for Rs 0.7 lakh, payback about 7 months.

## Which figure your buyer sees

A parboiled mill's fossil CO2 is its power bill; the husk is biogenic and reported apart, though its methane and nitrous oxide count. A hulling unit's footprint is almost all grid power, so kWh per tonne is the whole story.

## Per mill, per year (estimate)

- Medium parboiled: 545,460 kWh x 0.675 kg = 368 t fossil CO2
- Medium parboiled husk: (384 toe minus 47 toe of power) x 41.868 GJ x 100 kg = about 1,410 t biogenic
- Small parboiled: 109,092 kWh x 0.675 = 74 t fossil
- Hulling: 180,000 kWh x 0.675 = 122 t fossil; 40 kWh x 0.675 = 27 kg per tonne of rice

Unit figures from TERI's Red Hills profile (2014-15). Biogenic CO2 uses the IPCC 2006 default for solid biomass; grid factor from CEA for FY 2025-26.

## What Senseible does here

Senseible reads your electricity bills into monthly kWh and CO2 at the CEA factor, which for a hulling unit is nearly the whole footprint and for a parboiled mill is its fossil line.

- [Your carbon number for buyers and banks](https://senseible.earth/msme-carbon-number)
- [Red Hills vs Villupuram energy](https://senseible.earth/answers/red-hills-vs-villupuram-rice-mills-energy-co2)
- [Bargarh mills by size](https://senseible.earth/answers/bargarh-rice-mill-energy-by-capacity)
- [Rice mill energy benchmark](https://senseible.earth/answers/rice-mill-energy-per-tonne-benchmark)

Sources: [TERI, Energy profile: Red Hills rice mill cluster (SAMEEEKSHA, 2014-15 data)](https://sameeeksha.org/pdf/clusterprofile/RedHills_RiceMills_TamilNadu.pdf), [CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en), [IPCC 2006 Guidelines, Volume 2 Energy](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html)

Last reviewed 2026-10-31.