What happens to coal use when a galvanizing furnace switches to a biomass gasifier?

All 840 t of semi hard coke coal a year goes, replaced by 1,350 t of wood and 82,800 kWh in BEE's Howrah report. Fossil CO2 falls by about 1,380 t a year at our Indian coal factor, far above the report's 97 t. Cost Rs 44.17 lakh, payback 3.73 years (2010).

The unit BEE costed

• 7,500 t galvanized a year; zinc vat at 490 C.
• 600 t of semi hard coke coal a year in the furnace and 240 t on the job drying bed: 840 t, about 233 kg an hour.
• Proposed: a 1,000,000 kcal an hour gasifier burning 375 kg of wood chips an hour, 1,350 t a year, with 23 kW of fans and pumps.
• The furnace must be rebuilt for producer gas, with a chimney, and the flue gas used to dry jobs. Downtime: 14 days. Assumed life: 10 years.

The money, at 2010 prices

• Coal at Rs 6 a kg: Rs 50.40 lakh a year.
• Wood at Rs 2.50 a kg: Rs 33.75 lakh. Power: Rs 4.21 lakh. Extra labour: Rs 0.60 lakh.
• Net saving Rs 11.84 lakh against Rs 44.17 lakh: 3.73 years.
• A 10% rise in wood price takes about Rs 3.4 lakh off the saving, so lock a supply contract before you build.

Why the report's 97 t is wrong

The report states 1.17 t of CO2 per tonne of coal, which on 840 t would be 983 t, then prints 97 t. Both are low. At our Indian coal factor of 1.76 t per tonne, 840 t is about 1,478 t of fossil CO2. Semi hard coke is partly carbonised and likely emits more per tonne, so treat 1,478 t as a floor and ask your supplier for a carbon or calorific test.

Wood CO2 is biogenic: report it separately, not in Scope 1. Methane and nitrous oxide from burning wood do count, about 40 t CO2e a year by IPCC defaults, and the gasifier's power adds about 56 t in Scope 2.

Before you commit

• Wood at 375 kg an hour is about 4.5 t a day per shift. Check storage, drying and a steady supplier.
• Keep weighbridge slips for every wood load; a buyer or lender will ask where it came from.
• Run tar and ash handling past the pollution control board early.

One galvanizing unit, one year (estimate)

• Before: 840 t coal x 1.76 = 1,478 t CO2 (197 kg per t galvanized)
• After, power: 82,800 kWh x 0.675 = 56 t CO2
• After, wood methane and nitrous oxide: 1,350 t x 0.030 = 40 t CO2e
• Fossil cut: about 1,382 t CO2e a year
• Biogenic CO2 from wood, reported separately: about 2,360 t

Coal at India's BUR-2 factor for Indian coal, 1.76 t CO2 per tonne. Wood at IPCC 2006 defaults (15.6 GJ per tonne; 112,000 kg CO2, 30 kg methane and 4 kg nitrous oxide per TJ) with AR6 warming potentials. Grid CEA FY 2025-26.

What Senseible does here

Senseible reads coal and power invoices into monthly records with Indian coal at 1.76 kg CO2 per kg. It has no built-in wood factor, so add the wood lines worked out here. The green loan check shows what a lender will need for a project this size.

• Green loan readiness check
• Howrah galvanizers and CBAM
• Refractory kiln coal to gasifier
• Biomass boilers: methane stays in Scope 1
• Air preheater on a galvanizing furnace

Sources: BEE, Detailed project report: biomass gasifier replacing coal based furnaces, Howrah galvanizing cluster (2010, SAMEEEKSHA), IPCC 2006 Guidelines, Volume 2 Energy, Table 1.2 (net calorific values) and Chapter 2 tables, IPCC AR6 Working Group I, Chapter 7, global warming potentials (methane 27.0 non fossil, 29.8 fossil; nitrous oxide 273), 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.