Does swapping a diesel fired thermic fluid heater for a wood gasifier really pay back in 3 months in the Tiruppur manual?

In the Bureau of Energy Efficiency (BEE) Tiruppur manual, a 400,000 kilocalories (kcal) an hour heat setting heater moves from high speed diesel (HSD) at rupees (Rs) 123.12 lakh (1 lakh = 100,000) a year to wood at Rs 39.61 lakh including labour and power. Net saving Rs 83.51 lakh on Rs 22 lakh: 3 months.

The report's case

• Heater 400,000 kcal an hour, 7,200 hours a year. HSD 1,080 litres a day, 324,000 litres a year, bill Rs 123.12 lakh, which is Rs 38 a litre.
• Gasifier: 1,134,000 kilograms (kg) of wood a year at Rs 3 a kilogram = Rs 34.02 lakh. That is 3.5 kilograms of wood for each litre of diesel.
• Running costs: 6 extra workers at Rs 6,000 a month = Rs 4.32 lakh; power 27,000 kilowatt hours (kWh) at Rs 4.7 = Rs 1.27 lakh.
• Total Rs 39.61 lakh. Net saving 123.12 minus 39.61 = Rs 83.51 lakh. Investment Rs 22.00 lakh, so 22 / 83.51 = 0.26 years, about 3 months.

Three checks on the printed lines

• Power: 7.5 kilowatts (kW) over 7,200 hours is 54,000 kWh, not 27,000. The 27,000 equals 3,600 hours; the report does not say why. At 54,000 the power bill is Rs 2.54 lakh and the net saving Rs 82.24 lakh. Payback is still about 3 months.
• Cost: the manual's own cost table gives the 0.46 megawatt gasifier a total of Rs 22.76 lakh, against Rs 22.00 lakh here. 22.76 / 83.51 = 0.27 years, about 3 months.
• The manual's summary tables book the gasifier's fuel saving as 92 tonnes. We cannot tie 92 to the 1,134 tonnes of wood and 324,000 litres of diesel in this table, so use the rupee line, not the 92.

What would break the 3 months

Everything rests on wood at Rs 3 a kilogram against diesel at Rs 38 a litre. Our arithmetic from the report's own lines: the saving reaches zero when wood costs about Rs 10.4 a kilogram, and the payback stretches to 12 months at about Rs 8.4. Check the wood price you can actually get in tonnes a month, and whether the gasifier meets your state's air rules.

The carbon side

Diesel at 2.645 kilograms of carbon dioxide (CO2) a litre: 324,000 x 2.645 = 856,980 kilograms, about 857 tonnes of Scope 1 a year. Under the Greenhouse Gas (GHG) Protocol, direct CO2 from the combustion of biomass shall not be included in scope 1 but reported separately. So the wood's CO2 goes on its own line, and the 1,134 tonnes of wood bought are recorded in tonnes.

The report's sums, line by line

• Diesel: 1,080 litres x 300 days = 324,000 litres; Rs 123.12 lakh / 324,000 = Rs 38 a litre
• Wood: 1,134,000 kg x Rs 3 = Rs 34.02 lakh; labour 6 x 6,000 x 12 = Rs 4.32 lakh; power Rs 1.27 lakh
• Costs: 34.02 + 4.32 + 1.27 = Rs 39.61 lakh; net 123.12 minus 39.61 = Rs 83.51 lakh
• Payback: 22.00 / 83.51 = 0.26 years = 3 months
• Diesel CO2: 324,000 x 2.645 = 856,980 kg = about 857 tonnes

Rupee figures are the manual's at study-year prices. The CO2 line uses Senseible's diesel factor, not a figure from the manual.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so diesel litres and wood tonnes bought each month are on file before and after the change, with wood kept as its own fuel line. Heater efficiency comes from a test by a competent tester; Senseible keeps the fuel bills before and after.

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Sources: BEE, Manual on Energy Conservation Measures in Textile Cluster, Tirupur (prepared by Winrock International India, via SAMEEEKSHA), GHG Protocol Corporate Accounting and Reporting Standard, Scope 1 definition

Last reviewed 2026-11-05. Rupee prices are from the manual's study year (around 2010 to 2011). Diesel and wood prices have moved a lot, so redo the sum with today's prices and a current quote.