Should a Surat unit fit variable frequency drives (VFD) on its stenter blowers or buy a new stenter, going by the Bureau of Energy Efficiency (BEE) reports?

BEE's Surat reports put a drive on each of 8 stenter blowers for rupees (Rs) 2.03 lakh, saving 33,600 kilowatt hours (kWh) a year. A new stenter costs Rs 56.56 to 60.60 lakh and saves about 12 times as much. Per yearly kWh saved, the drives cost less than half as much.

What each report says

• Drives on blowers: a 4 chamber stenter has 8 blowers of 5.5 kilowatts (kW), their air flow set by a damper that is open 40 to 100%. A drive slows the motor instead. The report counts a 15% saving on 3.3 kW a blower: 0.5 kW x 8 blowers = 4.0 kW x 24 hours x 350 days = 33,600 kWh. At Rs 5.60 a kWh that is Rs 1.88 lakh. Cost Rs 2.03 lakh (Rs 1.78 lakh drives and panels plus Rs 0.25 lakh, which the cost table labels erection and commissioning). Payback 1.08 years. Carbon dioxide (CO2) printed: 28 tonnes.
• New 6 and 7 chamber stenters: Rs 56.56 and Rs 60.60 lakh, saving 403,200 and 412,608 kWh, Rs 22.58 and 23.11 lakh. Payback 2.5 and 2.6 years.
• Per kWh saved a year, the drives cost Rs 6.04 (2.03 lakh / 33,600), the 6 chamber stenter Rs 14.03 and the 7 chamber Rs 14.69. Our reading: this is a rough guide, since the machines differ in size and a new machine also replaces an old one.

How to choose

• If your stenter is sound and only its air flow is damper controlled, the drives are the small, quick step: one day or less of downtime, against two weeks and eight weeks of work for a new machine.
• If the machine is old, poorly insulated or has inefficient fans and main drives, the new machine's saving is larger. The reports list those as why the old machines draw 130 to 140 kW against 82 to 91 for the new ones.
• Do not add the two savings. Our reading: a new stenter's saving already includes better fans and drives, so the blower saving would be counted twice.

Printed figures that do not tie in the drive report

• The baseline draw is 3.5 kW a blower in the text and 3.3 in the annexure.
• Cost: Rs 1.78 lakh is written as 8 drives x Rs 0.22 lakh, which is Rs 1.76 lakh. The text says Rs 1.85 lakh in total, the cost table Rs 2.03 lakh, and the annexure Rs 1.90 lakh "for 4 VFD" although there are 8. Payback is 1.08 only on Rs 2.03 lakh; on Rs 1.78 lakh it would be 0.95.
• Downtime is 1 day in the summary and "no process down time", 2 to 3 hours, in the text.
• The audited units in Table 1.3 draw 542.4 kWh a day over 8 blowers, 1,019 over 16 and 406 over 6. That is 2.83, 2.65 and 2.82 kW a blower, below the 3.3 used. Our reading: 15% of those is 0.40 to 0.42 kW a blower, which is about 28,000 kWh for 8 blowers, some 15% under the printed 33,600.

The carbon dioxide line

The 28 tonnes printed is 0.83 kilograms of CO2 a kWh. At the Central Electricity Authority (CEA) factor for financial year (FY) 2025-26, 0.675, the 33,600 kWh give 22.7 tonnes. This is Scope 2: it is grid power you no longer buy.

The drive report, rebuilt

• Saving a blower: 15% x 3.3 kW = 0.495, printed as 0.5 kW
• Eight blowers: 0.5 x 8 = 4.0 kW x 24 x 350 = 33,600 kWh
• Money: 33,600 x Rs 5.60 = Rs 1.88 lakh; payback Rs 2.03 lakh / Rs 1.88 lakh = 1.08 years
• CO2 at 0.675: 33,600 x 0.675 = 22.7 tonnes, against 28 printed

Printed lines are the report's own at the report year's prices. The 0.675 is the CEA version 22.0 grid factor for FY 2025-26, an estimate.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so your stenter's gas and power bills are on file before and after either change. It does not read blower meters; take a clamp reading from the supplier.

• Surat 6 and 7 chamber stenter reports compared
• Stenter fuel and CO2 per metre of fabric
• Old report CO2 versus today's grid factor
• Green loan readiness check

Sources: BEE, Detailed project report: VFD for stenter machine blower, Surat textile cluster (SAMEEEKSHA), BEE, Detailed project report: stenter machine (6 chamber), Surat textile cluster (SAMEEEKSHA), BEE, Detailed project report: stenter machine (7 chamber), Surat textile cluster (SAMEEEKSHA), Central Electricity Authority (CEA), CO2 Baseline Database for the Indian Power Sector

Last reviewed 2026-11-05. Report figures are from BEE's Small and Medium Enterprises (SME) programme project reports, with electricity at Rs 5.60 a kWh. Check your tariff, your measured blower kW and current quotes before you rely on the paybacks.