Why do the Bureau of Energy Efficiency Vellore rice mill reports show no carbon saving for a husk boiler but hundreds of tonnes for a wood-saving dryer?

In five Bureau of Energy Efficiency (BEE) Vellore reports, three husk boilers save 125 to 348 tonnes of husk and print no carbon dioxide (CO2) saving, calling the husk renewable. Two fluidised bed dryers that save 231 and 297 tonnes of wood print 379 and 478 tonnes of CO2. One cluster, two treatments of biomass.

The five reports side by side

• Boiler, 0.5 tonnes of steam an hour: cost rupees (Rs) 8.00 lakh, groundnut husk saved 125 tonnes (178 down to 53), benefit Rs 4.38 lakh, payback 1.83 years, internal rate of return 37.10 percent. Printed CO2 saving: nil.
• Boiler, 0.75 tonnes an hour: Rs 8.82 lakh, husk saved 330 tonnes (462 down to 132), benefit Rs 11.55 lakh, payback 0.76 years, return 100.64 percent. CO2: nil.
• Boiler, 1 tonne an hour: Rs 10.96 lakh, husk saved 348 tonnes (495 down to 147), benefit Rs 10.44 lakh, payback 1.05 years, return 74.44 percent. CO2: nil.
• Fluidised bed dryer, 15 tonnes a day: Rs 25.69 lakh, wood saved 231 tonnes (825 down to 594), benefit Rs 8.42 lakh, payback 3.05 years, return 17.51 percent. CO2 saving printed: 379 tonnes.
• Fluidised bed dryer, 20 tonnes a day: Rs 34.85 lakh, wood saved 297 tonnes (990 down to 693), benefit Rs 12.05 lakh, payback 2.89 years, return 19.37 percent. CO2: 478 tonnes.

Two treatments of the same kind of fuel

Each boiler report says the project uses groundnut husk, which is a renewable source of energy, and that no greenhouse gas emission reductions will occur. Each dryer report says the project uses wood and will save about 379 or 478 tonnes of CO2 a year. That is 1.64 and 1.61 tonnes of CO2 for each tonne of wood. The reports print no factor behind these figures.

Husk and wood are both biomass, so the two treatments cannot both stand. Our reading: elsewhere on this site, CO2 from burning biomass is reported separately from Scope 1, so neither the nil nor the 379 and 478 is a cut in Scope 1. Methane and nitrous oxide from burning still count. Whichever figure you quote to a lender, say which treatment it uses.

What the dryer money is made of

The dryer benefit is wood at Rs 2,500 a tonne plus labour. For the 15 tonne dryer, 231 x 2,500 is Rs 5.775 lakh and the report's other line is Rs 2.64 lakh, which the text attributes to labour cost: together Rs 8.42 lakh. For the 20 tonne dryer, 297 x 2,500 is Rs 7.425 lakh plus Rs 4.62 lakh. Labour is 31 percent and 38 percent of the benefit. On wood alone our arithmetic gives paybacks of 4.4 and 4.7 years. The boiler benefits are husk only, at Rs 3,500 a tonne in the first two and Rs 3,000 in the third.

A label that does not match

The 1 tonne boiler's summary says the fuel saved is wood. Its text, annexure and cash flow price groundnut husk at Rs 3,000 a tonne, 495 tonnes down to 147. All three boiler reports start from an existing boiler at about 20 to 21 percent efficiency and move to 70 plus or minus 2 percent.

The 15 tonne dryer and the 1 tonne boiler, rebuilt from the reports

• Dryer wood: 825 minus 594 = 231 tonnes; 231 x Rs 2,500 = Rs 5.775 lakh. Add labour Rs 2.64 lakh = Rs 8.42 lakh (rounded)
• Dryer payback: 25.69 / 8.42 = 3.05 years. Wood alone: 25.69 / 5.775 = 4.4 years
• Dryer CO2 printed 379 tonnes: 379 / 231 = 1.64 tonnes for each tonne of wood
• Boiler husk: 495 minus 147 = 348 tonnes; 348 x Rs 3,000 = Rs 10.44 lakh. Payback: 10.96 / 10.44 = 1.05 years. CO2: nil

Report figures except the wood-alone payback and the CO2 per tonne ratios, which are our arithmetic.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the fuel invoices you upload give a year of use before a change to compare against. Tonnes of husk or wood burnt are on your purchase slips and stock books, which you add.

• Vellore rice mill boiler fuels
• Biomass or waste fuel in a boiler: Scope 1
• Husk sold to a power plant: who claims
• Green loan readiness check

Sources: BEE, Detailed project report: energy efficient boiler 0.5 tonnes an hour, Vellore rice mill cluster (SAMEEEKSHA), BEE, Detailed project report: energy efficient boiler 0.75 tonnes an hour, Vellore rice mill cluster (SAMEEEKSHA), BEE, Detailed project report: energy efficient boiler 1 tonne an hour, Vellore rice mill cluster (SAMEEEKSHA), BEE, Detailed project report: fluidised bed dryer 15 tonnes a day, Vellore rice mill cluster (SAMEEEKSHA), BEE, Detailed project report: fluidised bed dryer 20 tonnes a day, Vellore rice mill cluster (SAMEEEKSHA)

Last reviewed 2026-11-05. Report figures are from BEE's Small and Medium Enterprises (SME) programme project reports, at the report year's prices. Check today's husk, wood and labour costs and a current quote before you rely on the payback.