How much does a flat belt in place of V-belts save on an oil expeller drive?
About 4% of the motor's power. BEE's Alwar report changes the V-belts on a 50 HP expeller drawing 37 kW to a flat belt, saving 1.5 kW, or 4,500 kWh over 3,000 hours a year: Rs 21,600 then, 3 t CO2 now. Cost Rs 0.48 lakh a motor, payback 2.2 years.
Where V-belts lose power
A V-belt grips by wedging into the pulley groove and has to pull itself out again every turn. The report puts these wedge in and wedge out losses at 6 to 8% of power. With several belts on one drive, they are rarely equally tight, so some slip while others carry the load, and misalignment makes it worse. A flat belt weighs about a third as much and has no wedge loss.
The two drives side by side
- Power drawn: 37 kW with V-belts; 35.5 kW with a flat belt.
- Energy: 1.5 kW x 10 hours x 300 days = 4,500 kWh a year saved.
- Money: Rs 21,600 a year at Rs 4.8 a kWh. The report's summary also says Rs 0.58 lakh a year, which its own sum does not support.
- Cost: Rs 0.48 lakh a motor; about 5 hours to change over.
- Payback: 0.48 / 0.216 = 2.2 years.
The catch in an oil mill
The report itself warns that a flat belt needs an area free of oil. Oil on a flat belt makes it slip, and a slipping belt throws the saving away. Guard the drive from drips, keep the pulleys clean, and align them precisely with the right spacing for tension. Where oil cannot be kept off, a cogged or poly V-belt, which the report also mentions, is the safer change.
A bigger loss on the same motors
The audit found most motors rewound more than five times and running under loaded. A belt change saves 4% of what a tired motor draws. Check the motor's load and condition before spending on belts alone.
One expeller and a mill with ten
- One drive: 4,500 kWh x 0.675 = 3.0 t CO2 a year
- Ten drives: 45,000 kWh, 30 t CO2, Rs 2.16 lakh at the report's tariff
- The report says 4.0 t for one drive, on an older grid factor
Grid at CEA's FY 2025-26 factor, an estimate.
What Senseible does here
Senseible reads your electricity bills into monthly records with CO2 for the units. Its calculators help size a drive change before you buy, and the bills afterwards show whether it held.
- Senseible calculators
- Cogged or synchronous belts: saving
- Efficient oil expeller: kWh saved
- Alwar mustard oil mills: kWh per quintal
Sources: BEE, Detailed project report: flat belt in place of V-belt, Alwar oil mill cluster (2011, SAMEEEKSHA), CEA CO2 Baseline Database, version 22.0
Last reviewed 2026-11-01. Report figures are from a BEE SME programme project report; costs and paybacks are at the report year's prices.