How much wood and CO2 does an efficient 96-tray dryer save in a dyes or chemicals unit?
Wood use falls by 66 t a year in BEE's Ahmedabad report, by cutting a 96-tray batch from 48 to 30 hours. Your reported fossil CO2 does not fall: it rises about 2 t, because wood CO2 is biogenic and the new fans add 5,819 kWh. Cost Rs 3.86 lakh, payback 2.28 years (2010).
Old dryer against new
- Old: no insulation, propeller fans with no partition, uneven tray spacing. Measured efficiency 5.9%, 8.64 kg of wood per tray, 48 hours a batch.
- New: double wall with 50 mm mineral wool, four multi-blade fans on a 1 HP motor, roof dampers, digital temperature control. 9.5% efficient, 3.35 kg of wood per tray, 30 hours a batch.
- Saving: about 507 kg of wood a batch, 65.97 t over 130 batches a year.
- Electricity charged to the project: 5,819 kWh a year.
The money, at 2010 prices
- Wood at Rs 3,000 a tonne: Rs 1.98 lakh a year.
- Less power at Rs 5 a kWh: Rs 0.29 lakh.
- Net Rs 1.69 lakh against Rs 3.86 lakh: 2.28 years. Implementation takes about 13 weeks.
Why the report's 60 t CO2 cut is not a Scope 1 cut
The report converts the wood saved into 60 t of CO2 avoided. Wood CO2 is biogenic, so under the GHG Protocol it sits outside your scopes. What does count is the methane and nitrous oxide from burning wood, about 2 t CO2e for 66 t, and the dryer's electricity, about 4 t. Net, your reported footprint goes up slightly.
That is no reason to skip it. The case is the money, the faster batch, and less wood bought, which the report notes is mostly not from renewable sources.
What to check
- Weigh wood into the hot air generator for a week before and after; per tray figures are only as good as the scale.
- Confirm the drying time on your own product. The report's 48 to 30 hours was for cake at 0.43 kg of moisture per kg of bone dry product.
- Ask whether the old propeller fans come out. If they stay, the 5,819 kWh is extra; if they go, the real rise is smaller.
130 batches a year (estimate)
- Wood saved: (8.64 minus 3.35) kg x 96 trays x 130 = about 66 t
- Methane and nitrous oxide avoided: 66 t x 0.030 = 2.0 t CO2e
- Fan power added: 5,819 kWh x 0.675 = 3.9 t CO2
- Change in Scope 1 plus 2: about 2 t more
- Biogenic CO2 avoided, reported separately: 66 t x 1.75 = about 115 t
Wood at IPCC 2006 defaults (15.6 GJ per tonne; 112,000 kg CO2, 30 kg methane and 4 kg nitrous oxide per TJ), AR6 warming potentials; grid CEA FY 2025-26.
What Senseible does here
Senseible reads your electricity bills into monthly CO2 records. It has no built-in wood factor, so wood bills need the figures worked out here. The green loan check shows what a lender asks for before funding a dryer.
- Green loan readiness check
- Hybrid solar tray dryer
- Wood to gas hot air generator
- Biomass boilers: methane stays in Scope 1
Sources: BEE, Detailed project report: energy efficient tray dryer, 96 trays, Ahmedabad chemical cluster (2010, SAMEEEKSHA), IPCC 2006 Guidelines, Volume 2 Energy, Table 1.2 (net calorific values) and Chapter 2 tables, GHG Protocol Corporate Standard (biogenic CO2 reported separately from the scopes), CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0 (FY 2025-26 grid factor)
Last reviewed 2026-10-31. Equipment figures are from a BEE SME programme project report; costs and paybacks are at that report's prices. Recheck with today's fuel and power prices and a current quote.