How much wood does an efficient wood-fired hot air generator save over an old one?
Sixteen kg of wood an hour, 36 down to 20, in BEE's Ahmedabad report: 57.6 t of wood a year over 3,600 hours. Cost Rs 3.03 lakh, payback 2.18 years (2010). Fossil CO2 rises about 3 t from the blower, because wood CO2 is biogenic; the report's 53 t cut is not Scope 1.
Old heater against new
- Old: single pass, poor grate, high draught resistance. About 36 kg of wood an hour for 35,936 kcal of hot air; the report calls it 37% efficient in one place and around 32% in another.
- New 30,000 kcal an hour unit: three pass heat exchange, forced draught, controlled combustion, larger grate. About 20 kg of wood an hour.
- 12 hours a day, 300 days a year: 57,600 kg of wood saved.
- Blower load 1.86 kW, 6,696 kWh a year, which the report charges in full against the saving.
Better wood heater or gas heater
- Efficient wood unit: Rs 3.03 lakh, Rs 1.39 lakh a year, 2.18 years. Fossil CO2 up about 3 t.
- Gas unit, from the same report series: Rs 2.50 lakh, Rs 0.76 lakh a year, 3.29 years. Fossil CO2 up about 35 t, because gas is fossil and wood is not.
- If a buyer is asking for lower Scope 1 and 2, the efficient wood unit keeps them lower. If the buyer or lender questions where your wood comes from, gas avoids that question but raises your reported total.
What counts in your footprint
Wood CO2 is biogenic: report it separately. Methane and nitrous oxide from burning it stay in Scope 1, about 1.7 t CO2e for the 57.6 t saved. The blower's 6,696 kWh add about 4.5 t in Scope 2. Net, Scope 1 plus 2 rise by about 2.8 t.
Checks before you buy
- Weigh wood fed per hour for a week on the old unit; the saving is measured from that number.
- Ask whether the old blower stays. If it is replaced, only the difference in kWh counts.
- Ask the supplier for the outlet air temperature and flow at your dryer's load.
One hot air generator, one year (estimate)
- Wood saved: 16 kg x 12 h x 300 days = 57.6 t
- Money: 57.6 t x Rs 3,000 = Rs 1.73 lakh, less 6,696 kWh x Rs 5 = Rs 0.33 lakh: Rs 1.39 lakh
- Scope 1 avoided: 57.6 x 0.030 = 1.7 t CO2e; Scope 2 added: 6,696 x 0.675 = 4.5 t
- Biogenic CO2 avoided, reported separately: 57.6 x 1.75 = about 101 t
Wood at IPCC 2006 defaults with AR6 warming potentials; grid CEA FY 2025-26.
What Senseible does here
Senseible reads electricity and gas bills into monthly CO2 records, which is where either choice shows up. It has no built-in wood factor, so add wood using the figures here. The green loan check shows what a lender needs for the new heater.
Sources: BEE, Detailed project report: energy efficient hot air generator 30,000 kcal/hr, Ahmedabad chemical cluster (2010, SAMEEEKSHA), BEE, Detailed project report: gas fired hot air generator 30,000 kcal/hr, 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.