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

Canonical: https://senseible.earth/answers/galvanizing-coal-furnace-to-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](https://senseible.earth/green-loan-check)
- [Howrah galvanizers and CBAM](https://senseible.earth/answers/howrah-galvanizing-wire-units-cbam-carbon)
- [Refractory kiln coal to gasifier](https://senseible.earth/answers/refractory-kiln-coal-to-biomass-gasifier-co2)
- [Biomass boilers: methane stays in Scope 1](https://senseible.earth/answers/biomass-boiler-ch4-n2o-still-scope-1)
- [Air preheater on a galvanizing furnace](https://senseible.earth/answers/galvanizing-furnace-air-preheater-oil-saving)

Sources: [BEE, Detailed project report: biomass gasifier replacing coal based furnaces, Howrah galvanizing cluster (2010, SAMEEEKSHA)](https://sameeeksha.org/pdf/Howrah_galvinising/DPR_on_Biomass_Gasifier_for_Coal_Based_Furnaces.pdf), [IPCC 2006 Guidelines, Volume 2 Energy, Table 1.2 (net calorific values) and Chapter 2 tables](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html), [IPCC AR6 Working Group I, Chapter 7, global warming potentials (methane 27.0 non fossil, 29.8 fossil; nitrous oxide 273)](https://www.ipcc.ch/report/ar6/wg1/), [GHG Protocol Corporate Standard (biogenic CO2 reported separately from the scopes)](https://ghgprotocol.org/corporate-standard), [CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0 (FY 2025-26 grid factor)](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en)

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.